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DETAILED RESEARCH PROPOSAL

FOR DECE CAPSTONE 1
I. Capstone Project Title: Design and Development of a Methane Generation System for Individual Household Using
Residential Food Waste
II. BatStateU Research Agenda: Renewable Energy and Environmental Sustainability

III. Sustainable Development Goal: (Check all applicable SDG)

☐ SDG1: No Poverty ☐ SDG10: Reduced Inequalities
☐ SDG2: Zero Hunger ☐ SDG11: Sustainable Cities & Communities
☐ SDG3: Good Health & Well-being ☐ SDG12: Responsible Consumption & Production
☐ SDG4: Quality Education ☐ SDG13: Climate Action
☐ SDG5: Gender Equality ☐ SDG14: Life Below Water
☐ SDG6: Clean Water & Sanitation ☐ SDG15: Life on Land
☐ SDG7: Affordable and Clean Energy ☐ SDG16: Peace, Justice, & Strong Institutions
☐ SDG8: Decent Work & Economic Growth ☐ SDG17: Partnerships for the Goals
☐ SDG9: Industry, Innovation, & Infrastructure

IV. GROUP NUMBER: ICE 24-027

Project Leader: Araja, John Erasmouz Marie

Email Address: 21-04560@g.batstate-u.edu.ph
Contact Number:0915-222-8002

Project Staff (s): Briñes, Christine Joy

Email Address: 21-05990@g.batstate-u.edu.ph
Contact Number: 0993-757-2295

Project Staff (s): De La Rama, Princess Aira

Email Address: 21-01988@g.batstate-u.edu.ph
Contact Number: 0991-753-0860

Project Staff (s): Elomina, Alvin Jr. A.

Email Address: 21-09054@g.batstate-u.edu.ph
Contact Number:0993-456-0195

Project Staff (s): Enriquez John Loyd L.

Email Address: 21-02387@g.batstate-u.edu.ph
Contact Number: 0992-419-2574

Adviser: Engr. Clyde John Juneil Masicat

Email Address:clydejohnjuneil.masicat@g.batstate-u.edu.ph
Contact Number:
V. Proponent Agency:
Department: Department of Electronics Engineering
College: College of Engineering
Campus: Alangilan
VI. Cooperating Agency:
VII. Executive Brief:

The management of food waste and pig manure, as well as the rising cost of LPG for cooking, are major problems for
households in Tiquiwan, Rosario, Batangas. Pig manure and food waste are improperly disposed of, which makes waste
management issues worse and increases greenhouse gas emissions, pollution of the environment, and contamination of
nearby water supplies. Furthermore, household finances are being strained by the growing reliance on LPG, underscoring
the need for an economical and environmentally friendly solution to meet waste management and energy demands.

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This project proposes the development of a home methane generation system with an 97.92 L biodigester tank that
produces biogas from pig manure and food waste through anaerobic digestion. Every day, the system will process 1 kg of
pig manure and 2 kg of food waste, producing 0.1152 cubic meters of biogas. By providing cooking energy for one to three
hours, this quantity of biogas might lessen homes' dependency on LPG and provide a more cost-effective energy option. In
order to ensure optimal performance and user-friendliness, the system will also be outfitted with automatic sensors to
monitor critical factors including temperature, pH, and gas production. In order to promote sustainable farming methods,
the system will also generate digestate that is rich in nutrients and may be used as organic fertilizer.

In addition to producing digestate, a nutrient-rich organic fertilizer for sustainable agriculture, the suggested system will
turn food waste and pig manure into biogas, offering a cost-effective substitute for LPG in cooking. In addition to
addressing trash management, this method cuts greenhouse gas emissions and environmental pollutants. Economically
speaking, it provides long-term savings by lowering waste disposal and LPG prices. By converting waste into useful
resources, it promotes sustainability and economic resilience in Tiquiwan households while also supporting a circular
economy.
VIII. Rationale:

In Tiquiwan, Rosario, Batangas, the growing problem of disposing of organic waste and pig manure, along with economic
and environmental concerns, demands creative and long-lasting solutions. Pig manure and food waste in Tiquiwan are
frequently left or allowed to degrade in landfills, which reduces their ability to provide useful energy and greatly increases
greenhouse gas emissions like carbon dioxide and methane. A local waste management survey estimates that each
household in Tiquiwan produces 1-2 kg of food waste per day, which adds to the total waste load. Since many homes raise
pigs, there is also an abundance of pig excrement, with an estimated 1 kg of pig manure per family every day. Meanwhile,
family budgets are under further strain due to the growing price of LPG, the region's main cooking fuel. The cost of LPG
has been rising significantly in the Philippines; depending on the market, a 10-kg cylinder might cost anywhere from PHP
900 to PHP 1,200. For low-income families, maintaining economical cooking methods has become more challenging as a
result of this price increase.

By using anaerobic digestion technology to turn food waste and pig manure into biogas, this project, "Design and
Development of a Methane Generation System for Individual Households Using Residential Food Waste and Pig Manure"
tackles these two issues. Methane-rich biogas and nutrient-rich digestate are produced by the well-proven and
environmentally sustainable process of anaerobic digestion, which breaks down organic material without oxygen. To
maximize efficiency and guarantee usability, the system will have sensors to track vital variables including temperature,
pH, and gas yield.

A daily mixture of 5kg of food waste and pig manure will be processed by the suggested system in a 2:1:2 ratio (2 kg of
food waste, 1 kg of pig manure, and 2 liters of water) under thermophilic condition (40-55°C). This mixture can greatly
lessen households' dependency on pricey LPG by producing between 0.64 cubic meters of biogas each day, which is
sufficient to power cookery for 30-60 minutes. The system's digestate may be turned into organic fertilizer, encouraging
local farmers to utilize sustainable farming methods. Methane, a powerful contributor to climate change, will be reduced by
the system by diverting pig manure and food waste from open dumping and landfills.

Although pig manure alone can be utilized to produce biogas, According to (Leung and Wang, 2016), the potential for
methane generation rises significantly when mixed with food waste. In anaerobic digestion processes, the
carbon-to-nitrogen (C/N) ratio is essential. It is beneficial to combine pig manure with carbon-rich food waste because of
its comparatively high nitrogen concentration. By improving microbial activity and biogas generation, this mixture aids in
the optimization of the digestive process. Furthermore, food waste usually contains a lot of water, which helps to create the
perfect slurry consistency for effective anaerobic digestion.

This strategy is further supported by a number of IREDA (Indian Renewable Energy Development Agency) on the uptake
of biogas in comparable rural environments. Biogas systems that use organic waste and animal manure, especially pig
manure, have greatly increased household energy availability and decreased dependency on wood or LPG for cooking,
According to research done in India and other Southeast Asian nations. For instance, homes with biogas plants were able to
cut their reliance on LPG by up to 70%, resulting in long-term cost benefits, according to a research conducted in rural
India.

Pig manure and food waste are combined in this methane generating system to provide both environmental and practical
advantages. By lowering household spending on cooking fuel, it provides a long-term economic solution that might save
families hundreds of pesos a month on LPG. By turning organic waste into useful resources, digestate for fertilizer and
biogas for energy, it solves regional waste management issues in an environmentally friendly manner. This solution
promotes sustainable agriculture, lowers pollution, improves energy security, and supports a circular economic model.

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This project offers households in Tiquiwan a more effective, economical, and scalable alternative by integrating food waste
into the current method of using pig manure for biogas. In addition to being a renewable energy source, it promotes a more
resilient and sustainable community by enabling households to properly manage garbage and lessen their environmental
impact.
IX. Objectives of the Project:
This research aims to achieve the following objectives, which are critical to addressing the environmental challenges
identified:

Main Objective:
To design and develop a residential methane generation system using food waste as raw material and pig manure as
co-substrate.

Specific Objectives:
1.​ Design a methane generation system for processing food waste and pig manure to produce methane, including
details on system size, and its components.
2.​ Develop the methane generation system using affordable, locally sourced materials while ensuring proper
integration of components such as gas digesters, monitoring sensors, and environmental controls. The system
should be easy to operate and maintain in a household setting.
3.​ Evaluate the methane generation system under actual conditions to assess the consistency of methane production,
system stability, and overall performance, ensuring it meets specified output requirements.
X. Expected Output of the Project: (based on expanded 6Ps & 2Is of research)
Publication:
The project will result in a research paper detailing the design and development of the methane generation system,
including data on efficiency, cost-effectiveness, and environmental impact. This will be submitted to journals focusing on
renewable energy and environmental engineering.
Patent:
A patent application will be filed for the innovative design of the methane generation system, particularly for its integration
of automated sensors for temperature, pH, and gas monitoring in a compact household setup.
Product:​
A prototype methane generation system for individual households, capable of processing 4-8 kilograms of food waste daily,
will be developed. It will produce 1-2 cubic meters of biogas and nutrient-rich
People Service:
The system empowers communities by providing a sustainable solution for waste management and energy production,
reducing dependency on LPG, and supporting sustainable agricultural practices through organic fertilizers.
Place & Partnership:
The project collaborates with Tiquiwan, Rosario, Batangas, as the location. Partnerships with local waste management
authorities and agricultural cooperatives will be established to optimize resource use and system adoption.
Policy:
Promote the design, development, and evaluation of residential methane generation systems utilizing food waste and pig
manure to address waste management challenges, reduce greenhouse gas emissions, and provide a sustainable energy
source for individual households.
Social Impact:​
Enhances community sanitation and public health by minimizing improper waste disposal, promotes environmental
responsibility, and empowers households with self-sufficient energy solutions.
Economic Impact:
Reduces household energy expenses by offering an alternative to LPG, creates opportunities in the design and maintenance
of methane systems, and supports sustainable agriculture through the use of nutrient-rich digestate as fertilizer.
XI. Review of Related Literature:

XI.I Biogas
Biogas production converts organic waste into energy, addressing greenhouse gas emissions through anaerobic digestion
(AD). Biogas is regarded as an energy carrier since it contributes to the global energy mix [7, 8]. Compared to other fuel
types utilized in developing nations, the production of biogas reduces the need for firewood and fossil fuels, provides jobs,
lowers indoor smoke, and lessens odors [9–11]. In several regions of Asia, governments and development aid donors have
financially supported and promoted small-scale methane digesters due to these positive impacts. Biogas is a valuable
energy source that can be combusted in cogeneration units to produce green energy (Siddharth, 2006). It is composed of
60-80% of methane and 20-40% carbon dioxide, and trace compounds such as the water vapor (H2O) (5%), hydrogen
sulfide (H2S) (0.5%), nitrogen (N2) (1%), oxygen (O2) (0-2%) and ammonia (NH3) (0-1%) (Yang et al., 2014)

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Table 1: Biogas Composition
Gas Type Percentage in Biogas (%)

Methane (CH₄) 55–70

Carbon Dioxide (CO₂) 35–40

Nitrogen (N₂) 0–3

Hydrogen (H₂) 0–1

Hydrogen Sulfide (H₂S) 0–1

In the study “Assessing the Viability of Biogas Production from Food Waste” (2020), the author investigates the potential
of using food waste from Petroleum Development Oman (PDO) for biogas production through anaerobic digestion. The
research examines various food waste samples, including rice, dates, and mixed food, finding that carbohydrate-rich waste
generates the highest biogas yield, while fat- and protein-rich waste shows lower efficiency due to digestion complexities.
Biogas produced primarily consists of methane and carbon dioxide, with production influenced by factors such as substrate
composition and digestion conditions. The study underscores the environmental and economic benefits of biogas, including
reducing landfill waste, generating renewable energy, and producing nutrient-rich residues usable as fertilizers. An
economic evaluation suggests that biogas could replace 28.6% of LPG used at PDO’s Fahud camp, offering a cost-effective
alternative under certain conditions. While biogas presents significant advantages, the study acknowledges challenges like
greenhouse gas emissions from poor handling and the need for pretreatment to enhance production efficiency.
Recommendations include optimizing operational conditions and exploring biogas upgrading technologies to maximize
sustainability and value. (Abeer Al-Wahaibi, 2020)

However, It has been demonstrated that the potential for producing biogas is much increased when food waste is
co-digested with algae and cow manure [51, 52]. Other co-substrates, like goat, chicken, and pig dung, might, nevertheless,
have a greater effect. Anaerobic co-digestion of (catering) food waste with other livestock manure is rare and deserving of
investigation because of its high generation rate in our area, according to our review of the literature. The goal of this study
was to determine whether animal manure would be a viable co-substrate to increase biogas production during food waste
AD.

Figure 1. Effect of livestock manure addition on daily biogas production from AD of food waste. Image from (PDF)
BIOGAS PRODUCTION POTENTIAL FROM ANAEROBIC CO-DIGESTION OF FOOD WASTE AND ANIMAL
MANURE

The results of the 40-day biogas yield measurements conducted daily showed different results for each reactor bottle
(Figure 1). Reactor bottle B, which contained pig dung, was notable for producing the most biogas, reaching an astounding
maximum output of 144 mL gVS-1 on day 15. Reactor bottle C, which was supplied with chicken dung, produced a notable
maximum biogas volume of 101 mL gVS-1 on the same day. In contrast, the biogas quantities of Reactor bottles A
(modified with goat dung) and D (control) were comparatively lower, peaking at 72 mL gVS-1 and 68 mL gVS-1 on days
18 and 21, respectively.

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Figure 2.. Effect of livestock manure addition on daily biogas production from AD of food waste. Image from (PDF)
BIOGAS PRODUCTION POTENTIAL FROM ANAEROBIC CO-DIGESTION OF FOOD WASTE AND ANIMAL
MANURE

With a maximum cumulative biogas volume of 418 mL per gram of volatile solids (gVS-1), Reactor bottle B (modified
with pig manure) had the highest cumulative biogas yield (Figure 2). Reactor bottles C and A demonstrated cumulative
biogas quantities of 408 mL gVS-1 and 319 mL gVS-1, respectively, in close succession. With a cumulative volume of 313
mL gVS-1, however, food waste alone (Reactor Bottle D) produced the least amount of biogas. Understanding the potential
of different substrate combinations in improving biogas generation from catering food waste is essential, and these data
demonstrate the unique performance of each reactor.

Thus, (Ofon, et al., 2024) proved that Food waste could be diverted from landfills and other unsustainable waste
management solutions by adding animal manure to food waste AD to enhance biogas production. When compared to other
manures utilized in the study, pig manure greatly increased the production of biogas, highlighting the importance of
choosing the right co-substrate for anaerobic co-digestion and ultimate biogas enhancement.

Table 2: features of the FW and LM's trace components.

The table shows the features of the FW and LM's trace components. These components are crucial operating factors for
boosting anaerobic digestion's microbial activity. Anaerobic bacteria' metabolisms and enzyme activities are enhanced by
the addition of trace elements. Iron (Fe), nickel (Ni), cobalt (Co), and molybdenum (Mo) ions have been found to be
necessary for boosting the activity of methanogenic bacteria in numerous investigations [53]. In contrast to Speece et al.
(2006), the trace elements of Co2+, Se6+, Mo6+, and V5+ ions in the FW and LM were found to be substantially lower in
this investigation [54]. However, since the anaerobic microorganisms for the BMP and ATA tests had consistently adapted
to the FW, it was concluded that these components were adequate in anaerobic microorganisms for the anaerobic digestion
of organic material.

In order to estimate the methane yield for the proper mixing ratio of FW to LM, the elemental analysis of the FW and LM
was employed to calculate the theoretical methane yield. According to theory, the FW and LM produced 0.55 and 0.57 L
CH4/g VS of methane, respectively. The ratios of nitrogen to carbon (C/N) were 8.8 and 12.4, respectively [55]. As a
result, for FW and LM to co-digest steadily, the right mixing ratio must be used.

XI.II. Biogas Filtration

Biogas Scrubbers – A Technical Review
The study "Biogas Desulphurisation Techniques" (2024) provides an analysis of methods to reduce hydrogen sulfide (H2S)
in biogas, which is essential for preventing damage to gas engines and other equipment. H2S, a toxic gas formed during the

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anaerobic digestion of organic materials, can cause corrosion in engines, leading to shortened lifespans and increased
maintenance costs. The three main desulphurisation techniques discussed are:

1.​ Ferric Chloride Dosing: Iron chloride is added to the digester, reacting with H2S to form iron sulfide. It's effective
but comes with high operational costs due to the consumable nature of the chemical.
2.​ Activated Carbon Filters: Biogas is passed through activated carbon, where H2S is adsorbed and converted to
sulfur, CO2, and water. Though effective for very low H2S concentrations, it is costly, making it suitable for
specific cases like biogas upgrading.

Figure 3. Biogas scrubber

3.​ Biological H2S Reduction: This process uses aerobic bacteria to break down H2S. Air is introduced into the
digester to support the bacterial action, reducing H2S by up to 95%. This method is environmentally friendly and
cost-effective but requires careful control of oxygen levels to prevent disrupting the anaerobic process or creating
explosive conditions. Advanced systems like the AwiFlex analyzer can optimize oxygen flow and H2S reduction.

Removal of Hydrogen Sulphide

Mojica et al. (2018) demonstrated that a filtration system reduced non-combustible elements in biogas by 72% and
increased the combustible methane content by 54.38%. This improvement not only enhanced the energy output but also
reduced the presence of odor-causing impurities like H₂S. It is a major source of odor in biogas and states that filtration
technologies like chemical scrubbing and adsorption are effective in addressing this issue. By removing H₂S, filtration
ensures odorless biogas for end-use applications like cooking (Kapoor, 2017). Wardana (2013) discusses methods for H₂S
removal including adsorption on solids like activated carbon and biological conversion using sulfide-oxidizing
microorganisms. These techniques not only reduce H₂S levels but also eliminate the odor it produces.

XI.III. Waste Generation

XI.III.I. Food waste
Food waste and losses
Residential food waste refers to edible food that is discarded by households, including items like fruit and vegetable
peelings, table scraps, bread, grains, rice, pasta, eggshells, coffee grounds, and tea leaves. This waste occurs at the
consumer level, encompassing food that is fit for consumption but is consciously discarded.

The Environmental Protection Agency (EPA) defines food waste as uneaten food and food preparation wastes from
residences and commercial establishments such as grocery stores, restaurants, produce stands, institutional cafeterias and
kitchens, and industrial sources like employee lunchrooms. [4] Reducing residential food waste is crucial for conserving
resources, saving money, and minimizing environmental impact. The EPA emphasizes that when food is wasted, the land,
water, energy, and other inputs used in producing, processing, transporting, preparing, storing, and disposing of the food are
also wasted.

To address this issue, various strategies can be implemented, such as composting food scraps to create usable fertilizer,
thereby diverting waste from landfills. [6]Understanding the nature and impact of residential food waste is essential for
developing effective waste management practices and promoting sustainability.

Since the energy crises of the 1970s, anaerobic digestion technology has advanced extremely quickly (Deepanraj et al.,
2014). Nowadays, wastewater treatment is another application for anaerobic digestion technology, in addition to organic
waste treatment. Germany and Switzerland are leading nations in the world's biogas industry for the installation of
large-scale biogas facilities (Karthikeyan et al., 2018).

Characteristics of food waste

Food waste (FW) is composed of complex organic substances, including proteins, lipids, organic acids, and carbohydrate
polymers such as cellulose, starch, hemicelluloses, and lignin. The composition of FW varies based on factors such as
season, location, cooking methods, and consumption trends (Meng et al., 2015; Xu et al., 2018). FW can come from
different sources, including fruit and vegetable waste, household and restaurant waste, dairy, and brewery waste. Research

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shows significant variability in FW characteristics, such as pH, carbon-to-nitrogen ratio, carbohydrate, fat, protein content,
and biomethane potential (Fisgativa et al., 2016).

The degradability of FW components varies, with carbohydrates and proteins hydrolyzing more quickly than lipids. This
faster degradation leads to higher methane production from FW high in lipids and rapidly degradable carbohydrates. FW
high in lipids, like kitchen waste, generates more methane than FW rich in proteins and carbohydrates. Lipid content is
higher in FW and kitchen waste due to animal fats and oils, while fruit and vegetable waste has lower lipid content but
higher cellulose. Studies indicate that lipid content in FW influences methane generation, with higher lipid levels leading to
greater methane production (Bong et al., 2018; Y. Li et al., 2017).

Biogas production and methane concentration of food waste

The study of (A. Al-Wahaibi et al., 2020) investigated the biogas production potential from food waste. Numerous food
waste samples were included in the study, including bread waste, potato peel waste, meat waste, rice waste, dates fruit,
legume beans, leafy vegetables, fish waste, and two types of mixed food waste (fruit and vegetable waste).

Figure 4. The gas production profile for (a) mixed food-1, (b) fruit and vegetables, (c) bread, (d) potato peel, (e) mixed
food-2 and (f) meat samples over 24 h period.

Figure 5. The gas production profiles for (a) rice, (b) cow dung, (c) date fruit, (d) legume beans, (e) leafy vegetables and (f)
fish waste samples over a 24 h period.

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As seen in Figures 4 and 5, the total amount of gas produced by each sample was measured every three hours for a total of
twenty-four hours. 1 and 2. The gas produced by the mixed food-1 sample increased sharply in the first three hours (61
mL/1 g DM), then slightly after six hours (88 mL/1 g DM), and finally sharply after twelve hours (127 mL/1 g DM). With a
total gas production of 157 mL/1 g DM, the rising rate remained nearly constant for the next 24 hours. Likewise, the fruit
and vegetable sample exhibited a dramatic rise in the first three hours, reaching 89 mL of gas per 1 g of sample dry matter.
The gas production rate then increased gradually and steadily between 3 and 24 hours, reaching a maximum of 166 mL of
gas per 1 g of sample dry matter. This result is comparable to that found by Deressa et al.38. As was previously mentioned,
a high dry matter content and, consequently, a high organic matter content were observed in the bread waste samples. Bread
waste often has a high sugar, fiber, and fat content. Such organic-rich waste materials are a good substrate for the AD
process and have a high potential for creating biogas. Fig 4. shows the bread sample's gas production profile. 1. After
growing substantially during the first three hours (41 mL/1 g DM), the gas production rate increased significantly between
three and twelve hours, reaching approximately 202 mL of gas per 1 g of dry matter. After 12 hours, the rate of gas
generation increased marginally, and at 24 hours, it had reached 256 mL.

On the other hand, Figure 5 displays the methane content and biogas generation over a 21-day period for the chosen
samples (the mixed food waste, rice trash, legume beans, and date fruit). Overall, the amount of biogas produced increased
everyday in each sample. The samples of rice waste and mixed food waste had the highest gas production values at day
21—about 1600 and 1550 mL/1 g DM, respectively. The methane concentration varies across all samples, as seen in Figure
4a–d. Since volatile fatty acids were stored and then consumed, the significant change in the levels of methanogenic
population bacteria was ascribed to the variation in methane concentration. (Griffin et al.,20–) showed similar performance
(i.e., variation in methane concentration). The study examined the performance of a mesophilic anaerobic digester and
found that the volume of biogas produced and the concentration of methane varied during the digestion process. The pH of
the incubator environment changed as a result of several digesting processes that occurred during the incubation period.
Variations in pH have an impact on the growth of microbes through the AD process. The variation in methane content in
each sample reflects the particular pH range that each species of bacteria (i.e., methanogenic) need to be active.
Additionally, the type and quantity of bacteria are impacted by the digester's temperature fluctuations. Two sources of
energy were typically present in the incubator: the activity of the microbe and the ambient conditions. Methane levels in the
date fruit sample were below 20% on day one and then sharply rose to 55% on day three. After then, the methane content
dropped to less than 20%, where it stayed until day 21. However, the methane concentration in the rice waste sample
gradually decreased from day 3 to day 16, after which it sharply surged to reach approximately 64% on day 21. On day 1 of
the AD, the methane concentration in the legume bean sample was high (52%) and thereafter fluctuated until it reached
40% on day 21. Throughout the AD process, the mixed food waste sample's methane concentration varied by about 30%.

Figure 6. The total gas production profiles and % methane gas production over 21 days using (a) date fruit, (b) rice waste,
(c) legume beans and (d) mixed food waste samples.

The Production of Biogas Using Kitchen Waste

The study explores the viability of utilizing kitchen waste for biogas generation, emphasizing its potential as a sustainable
energy source for community-level applications. Biogas, primarily composed of 55-65% methane and 30-40% carbon
dioxide, is produced through anaerobic digestion of organic materials in the absence of oxygen. This process involves two
stages: the breakdown of complex organic molecules into simpler substances by acidic bacteria and the subsequent
conversion of these substances into methane by methanogenic bacteria.

The research employed an aluminum biogas plant with a 30 kg slurry capacity to evaluate biogas production under varying
kitchen waste-to-water ratios. Among the tested ratios, the 1:2 ratio (8 kg of kitchen waste to 16 liters of water) yielded

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optimal results, producing 0.258 m³ of biogas with a methane fraction of 48%. Key factors influencing production included
ambient temperature, slurry temperature, and solar intensity. Methane fractions began to appear from the third day of
digestion, with biogas production lasting up to 15 days under favorable conditions. The study highlights the benefits of
biogas systems, including reduced reliance on fossil fuels, mitigation of greenhouse gas emissions, and production of
valuable organic manure as a by-product. It further demonstrates biogas’s efficiency as an energy source, comparing it
favorably with conventional fuels like LPG, kerosene, and coal. This research underscores the potential of kitchen waste as
a sustainable feedstock for renewable energy production and its environmental and economic advantages (Agrahari and
Tiwari, 2013).

XI.III.II. Pig manure as co-substrate

However, according to (Leung and Wang, 2016), because long-chain fatty acids are formed, a high lipid concentration can
lead to system failure. This happens when the cellular membrane is destroyed, resulting in a decrease in the bulk transition
of soluble organics into bacteria. (Y. Li et al., 2017) also stated that FW with a high carbohydrate content will alter the
carbon and nitrogen ratio (C/N), which may lead to nutrient limitations and rapid acidification because of the increased
organic matter.

Thus, the application of co-digestion improves the anaerobic digestion process. The co-digestion process is in depth used
nowadays to prevent the issues related to the mono digestion of food waste. (Shi, et al., 2018). Food waste mono-digestion
frequently leads to a high C/N ratio and a poor buffer capacity. This is probably because the substrate is highly
biodegradable (Wang and Leung, 2016). Consequently, animal manure may be seen as an appropriate co-substrate because
of its abundance of different nutrients and high buffer capacity, which might raise the highest permitted OLR (up down to
10 kgVS/m3/day) and provide a more steady setting for anaerobic bacteria. (Xu et al., 2018).

An adult pig produces around 5kg of manure every day. This waste is 90% water and 7% volatile solids, which can produce
4.8 cubic feet of biogas daily. It is not advisable to use pig manure alone because it has high nitrogen content and low
amounts of carbon. It is also very alkaline, meaning that it can inhibit the growth of methane producing bacteria.
Methanogens prefer acidic conditions. However, you can improve pig manure biogas production by mixing it with cow
dung or biomass.
In Anaerobic co-digestion of pig manure and food waste; effects on digestate biosafety, dewaterability, and microbial
community dynamics by Dennehy et al., three feedstock ratios were tested: 85% PM/15% FW, 63% PM/37% FW, and 40%
PM/60% FW. The study revealed that increasing the food waste proportion boosted methane yields but did not affect
digestate biosafety or dewaterability. Reducing hydraulic retention time (HRT) from 41 to 21 days improved digestate
dewaterability and methane yields, though methane conversion efficiency decreased at the shortest HRT.

Substrate Consumption
Table 3. Different substrates with corresponding dry matter, ash content, total digestible nutrients and biogas yield used in
the household biogas digesters. doi: https://doi.org/10.3390/en5082911.

This table shows that pig manure produces the highest methane content at around 60%. Kitchen waste which contains a
high amount of fats from cooking oil and animal fat that can boost biogas production due to its high energy content. The
table compares different biogas substrates based on dry matter, ash content, total digestible nutrients, and biogas yield. Pig
manure with a dry matter content of 20–25%, produces 0.27–0.45 m³/kg TS. For household food wastes, leftovers food
offer a methane yield of 0.2–0.5 m³/kg TS. Other food wastes, such as egg waste and cereals, also demonstrate significant
biogas yields, ranging from 0.97–0.98 m³/kg TS for egg waste to 0.4–0.9 m³/kg TS for cereals.

The figure also supports the concept of synergistic effects in co-digestion. Combining multiple substrates for biogas
production often results in improved yields compared to mono-substrate digestion. This synergy occurs because
co-digestion balances nutrients, maintains a stable pH, and creates an optimized environment for microbial activity.

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Mata-Alvarez et al. (2000) emphasize that the high-fat content in some substrates, such as kitchen wastes, further enhances
biogas production. Additionally, Studies by Levi (2009) and Li et al. (2009) found that co-digestion generates more
methane than using a single substrate, showing the benefits of combining different organic materials. These findings show
the importance of substrate combinations for maximizing biogas production.

Table 4. Methane Yield and Digestate Characteristics at Different Pig Manure / Food Waste Amount Ratio
PM/KW Content HRT DAYS RESULT

85% PIG MANURE /15%, FOOD WASTE 41 Stable operation; lower methane yield efficiency.

63%PIG MANURE /37% FOOD WASTE 29 Increased methane yield

40% PIG MANURE /60% FOOD WASTE 21 Methane yield peaked ( Highest volumetric yield but
reduced efficiency )

Moreover, Ratios around 1:1 or slightly skewed towards pig manure often yielded the best results but are prone to
acidification which slows the retention time and prone to VFA inhabitants . Anaerobic co-digestion of kitchen waste (KW)
and pig manure (PM) with seven different PM to KW total solids (TS) ratios of 1:0, 5:1, 3:1, 1:2, 1:3, 1:5 and 0:1 was
conducted at mesophilic temperature (35 ± 1°C) to investigate the feasibility and process performance. [47]

Table 5. "Methane Yield and Process Stability at Different Pig Manure (PM) to Kitchen Waste (KW) Ratios"
KW: PW Ratio Result

1:0 Moderate methane yield with the shortest digestion time (T80: 15 days);
stable solo digestion of Pig Manure.

5:1 Increased methane yield with a short T80 (21 days) and stable digestion
performance.

3:2 Overall Good and Balanced digestion performance with moderate methane
yield and low risk of VFAs accumulation (T80: 22 days).

1;1 Highest methane yield (409.5 mL/gVS) and biodegradability (85.03%) but
has not balanced decomposition/ digestion leading to high retention time
and VFA inhibation (T80: 27 days).

1:3 Reduced methane yield due to VFA accumulation; extended T80 (49 days);
risk of methane inhibition.

1:5 Severe VFA-induced methane inhibition with a long T80 (62 days);
instability due to high KW content.

0:1 Methane yield suppressed by acidification; long digestion time (T80: 61

days); unstable solo KW digestion.

The study recommended a 3:2 KW: PW ratio for optimal methane production, stability, and process efficiency due to its
balanced C/N ratio and minimal risk of VFAs accumulation. Excessive KW (>50%) led to acidification and methane
inhibition, highlighting the importance of maintaining appropriate substrate ratios for stable anaerobic digestion.

In addition, the study "Food Waste Management for Biogas Production in the Context of Sustainable Development" (2022)
explores the utilization of food waste as a substrate for anaerobic digestion (AD) to produce biogas, emphasizing its
alignment with sustainable development and circular economy principles. It highlights that food waste from sources like
dairy, meat, fish, fruits, vegetables, and breweries is rich in nutrients and organic matter, making it ideal for co-digestion
with other materials. Pretreatment methods, including physical (e.g., mechanical, thermal), chemical (e.g., acid, alkali), and
biological (e.g., enzymatic, microbial), are identified as critical for enhancing degradation efficiency and improving biogas
yield. These methods break down complex organic compounds, facilitating more efficient conversion into biogas. The
study concludes that the integration of food waste into anaerobic systems not only reduces environmental impact but also
supports renewable energy production, emphasizing the need for optimized processes to maximize both energy recovery
and waste management benefits. [48]
​
XI.IV. Anaerobic Digestion
Anaerobic digestion of organic matter produces biogas, which transforms the substrate into renewable energy [5,6]. It is a
multifaceted microbial process that breaks down organic materials into biogas and organic fertilizer through a sequence of
metabolic events. Kumar and Samadder (2020) presents a comprehensive analysis of the anaerobic digestion process,
emphasizing its effectiveness as a waste management technique and a renewable energy source. Several tactics are

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described for improving reduced process instability and methane yield are substrate prerequisites, two or more substrates
being treated and co-digested [18]. Hydrolysis, acidogenesis, acetogenesis, and methanogenesis are the four main steps of
the process (Fig. 1)[13].

Hydrolysis
hydrolysis is the breakdown of complex organic materials like proteins, lipids, and carbohydrates into soluble organic
molecules like sugar, fatty acids, amino acids, and other related substances. Because hydrolysis produces volatile fatty
acids (VFA) and other harmful byproducts, it is typically the slowest or rate-limiting phase [14]. In most cases, pre-treating
the substrates speeds up the hydrolysis stage [15]. Hydrolysis and liquefaction of complex and insoluble organics are
necessary to convert these materials to a size and form that can pass through bacterial cell walls for use as energy or
nutrient sources.

Acidogenesis
acidogenesis (or fermentation) is The initial step Along with hydrogen (H2), carbon dioxide (CO2), and other byproducts,
the reduced organic molecules from the hydrolysis stage further break down into short-chain fatty acids during the second
stage. Acidogenesis is the process in which bacterial fermentation (by the acidogens) of the hydroylsis products results in
the formation of volatile acids. The hydrogen-producing acetogens convert the volatile acids (longer than two carbons) to
acetate and hydrogen.These microorganisms are related and can tolerate a wide range of environmental conditions. Under
standard conditions, the presence of hydrogen in solution inhibits oxidation, so that hydrogen bacteria are required to
ensure the conversion of all acids.

Acetogenesis
The organic acids produced during the acidogenesis stage are transformed into acetic acid, H2, and CO2 during the third
step, known as acetogenesis. Products from acidogenesis, which can not be directly converted to methane by
Methanogenic bacteria, are converted into methanogenic substrates during acetogenesis. VFA and alcohols are oxidised
into methanogenic substrates like acetate, hydrogen and carbon dioxide. VFA, with carbon chains longer than two units and
alcohols, with carbon chains longer than one unit, are oxidized into acetate and hydrogen. The production of hydrogen
increases the hydrogen partial pressure. This can be regarded as a “waste product“of acetogenesis and inhibits the
metabolism of the acetogenic bacteria. During methanogenesis, hydrogen is converted into methane. Acetogenesisand
methanogenesis. usually run parallel,as symbiosis of two groups of organisms.

Methanogenesis
Karki, et al.( 2005) added that methanogens convert acetate and hydrogen to methane and carbon dioxide. Or
Methanogenesis -methane, CO2 and water are produced by bacteria called methanogens.The primary route is the
fermentation of the major product of the acid forming phase, acetic acid, to methane and carbon dioxide. Bacteria that
utilize acetic acid are acetoclastic bacteria (acetate splitting bacteria). The overall reaction is:

CH3COOH —> CH4 + CO2

About two-thirds of methane gas is derived from acetate conversion by acetoclastic methanogens. Some methanogens use
Hydrogen to reduce Carbon dioxide to Methane (hydrogenophilic methanogens) according to the following overall
reaction:

4H2 + CO2 —> CH4 + 2H2O

Circumstances in treating solid wastes, acetate is a common end product of acidogenesis. This is fortunate because acetate
is easily converted to methane in the methanogenic phase. Due to the difficulty of isolating anaerobes and the complexity
of the bioconversion processes, much still remains unsolved about anaerobic digestion.

The principal acids produced in Stage 2 are processed by methanogenic bacteria to produce CH4. The reaction that takes
place in the process of CH4 production is called Methanization and is expressed by the following equations:

CH3COOH —> CH4 + CO2

Acetic acid Methane Carbon dioxide

2CH3CH2OH + CO2 —> CH4 + 2CH3COOH

Ethanol Carbon dioxide Methane Acetic acid

CO2 + 4H2 —> CH4 + H2O

Carbon dioxide Hydrogen Methane Water

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The above equations show that many products, by-products and intermediate products are produced in the process of
digestion of inputs in an anaerobic condition before the final product CH4 is produced.

Figure 7. Schematic diagram of processes occurring within anaerobic digestion. Image

from:https://images.app.goo.gl/jByi1Vur4YSuC9wX

XI.V. Factors affecting anaerobic digestion (AD)

XI.V.I. Acidity and alkalinity (pH)

During the AD process the pH is preferred to be within the ranges 6.0 - 8.5. The methanogens grow optimally at around
neutral pH and a pH outside this range can inhibit their growth, thus resulting in unstable digester performance and
sometimes even process failure. While an accumulation of ammonia causes the pH to rise, an accumulation of VFAs causes
the pH to fall. Nonetheless, digesters often have two natural buffering systems that keep the pH level within the neutral
range. The carbonic acid/bicarbonate/carbonate equilibrium (eq. 1) is a naturally occurring buffering system that keeps pH
levels from falling too low.

− + 2− +
𝐶𝑂2 + 𝐻2𝑂 ⇔ 𝐻2𝐶𝑂3 ⇔ 𝐻𝐶𝑂3 + 𝐻 ⇔ 𝐶𝑂3 + 2𝐻 (1)

This buffering system swings around the pH value of 6.0. Another buffering system is ammonia/ammonium equilibrium
(eq. 2) which prevents too high pH values.

+ +
𝑁𝐻3 + 𝐻 ⇔ 𝑁𝐻4
+ −
𝑁𝐻4 + 𝑂𝐻 ⇔ 𝑁𝐻3 + 𝐻2𝑂 (2)

Around pH 10, the ammonia/ammonium buffering mechanism can offer balance. However, feeding with highly degradable
feedstocks, lowering the temperature, or having an excessively high OLR can overload these buffering systems. An
increase in propionic acid concentration, a drop in pH, and an increase in the pH value are the successive indicators of
acidification.
CO2 content of the biogas produced. Additional indicators of the process imbalance include concentrations of acetic acid
greater than 0.8g/L and propionic acid to acetic acid ratios greater than 1.4.

XI.V.II. Temperature
Operating temperature is an important factor to determine the performance of the anaerobic digester (AD) reactors because
it is an essential condition for the survival and optimum adaptation of microbial activity. It can be distinguished between
three ranges of temperature: psychrophilic range (<20℃ mesophilic (30 - 42℃) or thermophilic ranges (43-55℃) (Al
Seadi et al., 2008) which also can directly affect retention time and gas production as shown in figure 2.

Figure 8. Operating temperature ranges and production rates of various types of bacteria (Kuria, J., & Maringa, M., 2008)

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Figure 9. Temperature ranges for anaerobic digestion. Optima are for mesophilic around 32-45°C and for thermophilic
around 55-70°C (Mata-Alvarez, 2015).

Thermophilic (55–70°C) or mesophilic (32–45°C) temperature regimes are used for the AD process. Because methanogens,
especially thermophilic methanogens, are sensitive to temperature changes, it is crucial to keep the digester's temperature
consistent. The rationale is that mesophilic methanogens are more diverse than thermophilic ones. With variations of ±3°C,
digesters operating in mesophilic conditions can continue to function normally. However, because of their irreversible
inactivation, temperature fluctuations may become more significant for mesophilic methanogens between 40 and 45°C.
Despite their inability to withstand temperature changes, thermophilic AD outperforms mesophilic AD by roughly 50% in
terms of growth and breakdown rates, which improves process efficiency. Other benefits of thermophilic AD over
mesophilic AD include the elimination of the need for fertilizer hygienization, less oxygen solubility, less inhibition from
ammonia buildup, and a greater capacity to alleviate the inhibition brought on by elevated OLRs. However, there are still
some reasons why the mesophilic AD is worth taking into account, including its increased resistance to environmental
fluctuations and the higher rates of food waste solubilization at mesophilic temperatures. Because of its high organic
content, mesophilic AD is generally more stable than thermophilic AD for food wastes. (Safoora, et al., 2019).

XI.V.III. Hydraulic Retention time (HRT)

Hydraulic retention time (HRT) can be simply defined as the average time that the slurry remains in a biogas digester. The
minimum HRT should be longer than the doubling time of the microorganisms to avoid washout. A longer retention period
results in a greater reduction of volatile solids, a larger digester volume, and a greater ability to adjust to changes in pH and
harmful substances. Lower retention periods, however, provide biogas of the same quality and quantity but necessitate a
smaller digester volume, which lowers the investment cost. Temperature, feed content, and organic loading rate (OLR) all
affect the ideal retention period. (Chandra, et al., 2012). As shown in table (2-4), under mesophilic conditions, a typical
HRT is 15- 30 days and slightly shorter under thermophilic conditions (Mao et al., 2015; Braun et al., 2010).

Table 6. Thermal stages of the digester, temperature and retention time (Al Seadi et al., 2008)
Thermal Stage Process temperature Retention time (days)

Psychrophilic Less than 20 70-80

Mesophilic 30-42 30-40

Thermophilic 43-55 15-20

XI.V.IV. Particle size

It has been demonstrated that food wastes with smaller particle sizes have more surface area available for the initial
absorption of exo-enzymes, which speeds up the breakdown process and enhances the production of biogas. It has been
demonstrated that feedstock size reduction can enhance the AD process in two ways: (I) increasing the production of biogas
from substrates with high fiber content, and (II) reducing the technical digestion time for all substrates. Food waste
comminution has the primary benefit of balancing the necessary retention periods for various chemicals, and it is frequently
advised prior to AD. However, excessive food waste comminution may result in the buildup of VFA and thus reduce
methane production. In a solid-state AD process as opposed to a submerged process, excessive size reduction of food
wastes may be more detrimental. According to reports, excessively tiny particle sizes in wet and dry digesters, respectively,
resulted in significant foaming and process failure. Therefore, choosing the right comminution equipment in relation to
digester type is essential since it can determine whether the AD process is effective or not. (Zhang & Banks, 2013).

XI.V.VI. C/N Ratio

The carbon-to-nitrogen ratio (C/N ratio) shows the balance of carbon and nitrogen in organic materials. A high C/N ratio
lowers gas production as nitrogen is used up quickly, while a low ratio leads to ammonia build-up, raising pH above 8.5

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and harming bacteria. According to (Mata-Alvarez, 2015), the best C/N ratio is between 20 and 30. This range provides
enough nitrogen for microbes to grow and avoids excessive ammonia accumulation.
The C/N ratio directly affects the anaerobic digestion (AD) process. A balanced ratio supports efficient microbial activity,
enhances biogas production, and ensures the stability of the digestion process. High C/N ratios slow down microbial
metabolism and reduce gas yields due to nitrogen deficiency. On the other hand, low C/N ratios result in excess ammonia
which is toxic to methanogens and can cause system failure. To balance the ratio, materials with high C/N, such as plant
waste that can be mixed with low C/N materials like manure or food waste. Maintaining the C/N ratio close to 25 ensures
an efficient digestion process, steady biogas output, and minimizes risks of system imbalance or failure. Dry weight of
nitrogen as a percentage of the feedstock weight and C/N ratios of some selected feedstock are shown in table 2 and table 3
shows C/N ratio for food and kitchen waste.
Table 7. Dry weight of nitrogen and C/N ratios of some selected feedstocks (Eggeling et al., 2019)

Table 8. C/N ratio for different sources of kitchen waste (Xu et al., 2018)

XI.V.VII. Organic loading rate (OLR)

The organic loading rate (OLR) is the amount of organic material (volatile solids, VS) fed daily per liter of digester volume
(g VS/L/day) (Mata-Alvarez et al., 2017). A higher OLR increases the organic matter available for microbial activity which
can enhance biogas production. However, if then OLR exceeds the digester’s capacity it can disrupt the balance of
microbial communities and lead to system failure. Specifically, the rapid multiplication of acidogenic bacteria which break
down organic matter into acids can overwhelm the system. Since methanogenic bacteria responsible for converting acids
into methane that reproduce more slowly they may not be able to process the acids fast enough. This leads to an
accumulation of volatile acids and a drop in pH, which inhibits methanogen activity. Thus, properly controlling the OLR
ensures that the microbial communities in the digester remain balanced, maximizing biogas yield, and maintaining stable
operation of the AD process (Demirbas, 2009).

Organic loading rate is related to hydraulic retention time by the following equation (Rowse, L. E., 2011):
(𝑄)(𝐶𝑉𝑆) 𝐶𝑉𝑆
𝑂𝐿𝑅 = 𝑉𝑟𝑒𝑎𝑐𝑡𝑜𝑟
= 𝐻𝑅𝑇
Where:
OLR = Organic loading rate (g VS/L/day)
Q = volumetric flow rate (m3/d)
Cvs = concentration volatile solids (kg VS/m3)
Vreactor = reactor volume (m3)
HRT = hydraulic retention time (day)

According to research conducted by (Paritosh et al., 2017), (Xu et al., 2018), (Liu et al., 2017), and (Babaee & Shayegan,
2011), OLR for successful digestion of food waste is between 1.4 and 22 KgVS/m3. Under thermophilic digestion of food
waste was 2.5 g of volatile solids (VS)/L/day with methane yield (MY) of 541 mL/g of VSadded. In addition, the optimal
OLR under mesophilic condition was 1.5 g of VS/L/day with a MY of 371 mL/g of VSadded. At the same OLR, the MY

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under thermophilic condition was 33–49% higher than that under mesophilic condition. Under thermophilic conditions,
steady methane production and degradation efficiency were achieved with a considerably high OLR of 7.5 g of VS/L/day.
Under mesophilic conditions, stability was obtained only when the OLR was controlled below 2.5 g of VS/L/day. Results
also revealed that food waste is a highly desirable substrate with a high bearing OLR under the thermophilic condition of
biogas production (chao L. et al., 2017.)

Experiments conducted by (Babaee & Shayegan, 2011) on methane production from vegetable waste concluded that an was
ideal for the highest and stable methane and biogas yield. An increase in OLR usually results in an increase in total
methane yield, however, if a certain OLR value is exceeded, the process can be unstable and process failure may even
occur (Mata-Alvarez et al., 2014). .

XI.V.VIII. Total solids content (TS) and Volatile solid (VS)

The weight of the dry matter of an anaerobic digestion substrate is called total solids (TS). A total solids (TS) content of
5% to 35% can be used for anaerobic digestion [31]. Based on the TS content of the feedstock, anaerobic digestion is
classified into three categories: wet (<10% TS), semi-dry (10–20% TS), and dry (>20% TS). Every technique, whether
wet or dry, has pros and cons of its own.

Dry anaerobic digestion (SSAD) stands out as a more advanced and sustainable technology. It processes dry, stackable
biomass with a solid content of 20-55% in batch-operated gas-tight chambers, significantly reducing water dependency.
Solid-state anaerobic digestion is highly tolerant to impurities, accommodates a broad range of organic substrates, and
operates with minimal manual intervention due to its automation. Unlike wet systems, SSAD avoids complex
pre-processing, offers a faster and more stable degradation process, and is less labor-intensive.

Wet anaerobic digestion, the most traditional method, mixes biomass with water to create a slurry containing 10-15% total
solids. While effective for small-scale biogas plants, this system's high water requirement makes it unsuitable for
large-scale operations in water-scarce regions. according to certain research, wet anaerobic digestion plants outperform dry
anaerobic digestion plants in terms of energy balance and economic performance [32,33]. Channeling and insufficient
microbial interaction with the substrate are two of the main drawbacks of dry anaerobic digestion [33]. Furthermore,
inhibitory substances such ammonia, VFAs, and heavy metals can accumulate more easily in dry processes [30]. According
to Ahmadi-Pirlou et al. [29], TS has an impact on methane output. In the dry process, they discovered that the digester at
20% TS produces more methane than the digesters at 25% and 30% TS. According to another study, the production of
biogas rises to 8% TS before declining to 10% TS [34].

Volatile solids (VS) can be defined as the percentage of the solid material of the digestion raw materials inside the digester
that can be broken down by the bacteria to produce biogas. This portion varies from one organic waste material to another.
VS content can be calculated by dividing the weight of volatile solids in the raw material by the total weight of solids in
raw material and normally expressed as a percentage of the total solids content (IRENA, 2016). VS content of an anaerobic
digestion substrate is often an essential parameter in predicting methane production from the substrate (Schmidt, 2005).

XI.V. IX. Mixing Ratio of Food Waste and Pig Manure (mixing)
Based on their volatile solids (VS) concentrations, food waste (FW) and livestock manure were combined in a batch system
at a set ratio of 3:2 to perform the anaerobic co-digestion process. Evaluating these co-substrates' capacity to produce
biomethane and their biodegradability was the primary goal. The experimental approach outlined by Ofon et al. [65] and
Ndubuisi-Nnaji et al. [66] was used, but with a few minor adjustments. The experiment was made easier by using 100 mL
amber borosilicate glass serum bottles (Wheaton 223766, USA) as reactors, which were sealed with 20 mm aluminum
crimp seals for the headspace vials that include PTFE/Butyl septa (Wheaton W224224, USA).

Each reactor had a specific designation, ranging from A to D, and was made up of particular combinations shown in Table
4. For example, Reactor A held 5 g of acclimated cow dung, 10g of goat manure, and 10g of food waste. Likewise, Reactor
B included 5 g of acclimated cow dung, 10 g of pig manure, and 10 g of food trash. 10g of food waste, 10g of chicken
manure, and 5g of acclimated cow dung were all present in Reactor C. Reactor D, the control, contained only 5 g of
acclimated cow dung and 10 g of food waste. Each digester received 5 g of cow manure (inoculum) to start the digestion
process.

Over the course of the 40-day reaction time (RT), the reactors were kept in a thermostatic water bath at a constant
temperature of 40 ± 2°C until no discernible biogas production was seen. The biogas produced throughout the procedure
gathered in the reactors' headspace. The reactors were manually rotated every day prior to biogas measurement in order to
guarantee efficient mixing and homogeneity. Using a 1.5% sodium hydroxide solution to remove carbon dioxide from the
collected biogas, the liquid displacement technique was used to gauge the rate of biogas generation. This method adhered to
the methodology outlined by (Tayyab et al., 2019) [67].

Table 9. Mixing ratios of feedstock and substrates

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Treatment mixing ratios (g)

Reactors
Feedstock Substrate Inoculum

A Food waste (10) Goat manure (10) Cowdung (5)

B Food waste (10) Pig manure (10) Cowdung (5)

C Food waste (10) Chicken manure (10) Cowdung (5)

D Food waste (10) not applicable Cowdung (5)

The inoculum and manures were analyzed and compiled in Table 5. The results of the analysis indicated that The animal's
pH was within an acceptable range. Range for AD in goats is 7.94 ± 0.2. manure to the inoculum at 8.16 ± 0.15.
Interestingly, pH Food waste from the canteen had an acidic pH value. = 4.93), whereas the manure ones were inside the
alkaline range, highlighting the necessity of co-digestion. Food waste's acidic pH and Animal manure's alkaline pH has also
been documented by several writers [67,70,71]. Total amount of solids was 29.32 ± 0.21 for food waste and 67.84 ± 0.45
for 16.91 ± 0.18 for pig dung, chicken manure, and Goat manure: 33.65 ± 1.10. The substrate and co-substrates had notable
concentrations of volatile solids, suggesting the presence of sizable degradable sections for biodegradation and microbial
attack. The C/N ratios of goat dung (17.9) and chicken manure (10.1), with the exception of the inoculum (25.1), food wa
ste (20.7), and pig manure (23.1), were outside the ideal range (20–30). According to studies, a high carbon content
provides more carbon for the production of biogas (methane). However, as a significant amount of nitrogen is necessary for
their growth, low nitrogen concentrations may restrict methanogenic activity [72,73].

Table 10. Physicochemical characteristics of substrate, co-substrates and inoculum

Food waste Chicken Manure Pig Manure Goat Manure Inoculum

pH 4. 96 ± 0. 06 8. 10 ± 0. 02 7. 84 ± 0. 04 7. 94 ± 0. 03 8. 16 ± 0. 15

TS (%) 29. 32 ± 0. 21 67. 84 ± 0. 45 16. 91 ± 0. 18 33. 65 ± 1. 10 16. 91 ± 0. 02

VS (%) 26. 03 ± 1. 20 47. 5 ± 0. 26 26. 93 ± 0. 21 82. 21 ± 1. 14 10. 25 ± 0. 10

C/N 20. 77 ± 0. 31 10. 1 ± 0. 11 23. 1 ± 0. 03 17. 97 ± 0. 12 25. 1 ± 0. 21

Anaerobic Mono-digestion and Co-digestion

Luo and Pradhan (2024) provides an in-depth analysis of anaerobic digestion processes involving food waste and sewage
sludge. It evaluates two key approaches: mono-digestion and co-digestion, highlighting their respective benefits and
challenges.

Mono-Digestion: This method involves digesting a single type of substrate, such as food waste or sewage sludge,
independently. While effective for specific waste types, mono-digestion may face issues like nutrient imbalances and
process instability, particularly when handling food waste alone due to its high organic load and potential for acidification.

Co-Digestion: This approach combines more than one type of organic material and is digested at the same time to create a
balanced substrate mix. Co-digestion improves biogas production and process stability by leveraging the complementary
characteristics of the substrates—food waste provides a high organic load, while sewage sludge offers buffering capacity
and nutrients. However, challenges include the need for optimal substrate mixing and management of inhibitory
compounds like ammonia and sulfides.

Mixing Unit
Teeboonma (2021), stated that the two-stage system incorporates a dedicated acid tank and gas fermentation tank, where
the mixing unit in the acid tank ensures the uniform distribution of substrates pig manure, food waste, and water. This
mechanical mixing is essential to prevent sedimentation, maintain a homogeneous environment for microbial activity, and
enhance the breakdown of organic matter during hydrolysis and acidogenesis. By ensuring consistent substrate mixing, the
mixing unit facilitates better microbial contact with the feedstock, leading to improved biogas yields. This study
demonstrated that mixing units are pivotal in preventing stratification, which can inhibit microbial activity, and in
supporting the continuous operation of the anaerobic digestion process. Properly mixed substrates ensure stable
biochemical reactions throughout the digestion process, particularly during the critical stages of acetogenesis and
methanogenesis.

Pretreatment with mixing unit

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Recent studies by T.Y in 2017 states that the operational conditions for anaerobic digestion using a combination of these
substrates. The research highlights the importance of pretreatment methods and the use of a mixing unit to optimize the
digestion process. Pretreatment, such as thermal or chemical methods, helps break down complex organic molecules into
simpler forms, enhancing their biodegradability and availability to microbes. The integration of a mixing unit ensures a
homogeneous distribution of the substrates, which prevents stratification and dead zones within the digester. This
uniformity improves microbial activity and ensures consistent biogas production. The study also emphasizes the need to
monitor critical parameters such as temperature, pH, and mixing intensity to maintain optimal conditions.

Digestate Recirculation Mixing

The study compared the performance of solid anaerobic digestion (SAD) batch systems with liquid digestate recirculation
to traditional wet anaerobic digestion (WAD) systems for organic waste treatment. The findings revealed that digestate
recirculation significantly influences volatile fatty acid (VFA) concentrations and enhances overall system efficiency.
Recirculating the liquid digestate helps to regulate VFA levels by redistributing these metabolic intermediates throughout
the digester, preventing localized accumulation that could lead to process inhibition. Furthermore, the continuous flow of
liquid digestate ensures better contact between microorganisms and organic material, promoting more complete substrate
degradation. Systems incorporating digestate recirculation demonstrated higher methane production compared to those
without, as uniform microbial activity and diluted inhibitory compounds contributed to improved biogas yields. The study
also highlighted how digestate recirculation alters metabolic pathways during digestion, favoring processes that enhance
methane generation. These findings underscore the potential of liquid digestate recirculation as a practical strategy for
improving system stability and biogas production in high-solids anaerobic digestion.

Mechanical Mixing
According to a study by Shinh et al. (2020), the intensity and duration of mixing significantly influence the performance of
anaerobic digestion systems and biogas production rates. The researchers observed that optimal mixing enhances the
interaction between microorganisms and substrates, improving the digestion process's overall efficiency. However, they
cautioned that excessive mixing can disrupt sensitive microbial communities, such as methanogens, which play a vital role
in methane production. Furthermore, over-mixing increases energy consumption, making it less economically viable. The
study underscores the importance of balancing mixing intensity and duration to maximize biogas yields while minimizing
operational costs. Sharma et al. highlighted that mixing strategies should be tailored to specific feedstocks and digester
designs to ensure optimal performance and system stability.

Gas Recirculation Mixing

A study by Hala Chaoui et al. (2008) investigated the impact of mixing frequency on biogas yield in anaerobic digesters,
focusing on a pilot-scale system employing gas recirculation mixing. This innovative method utilizes the pressure of
produced gas as the source of mixing, effectively enhancing substrate-microorganism contact and improving digestion
efficiency. The researchers found that optimizing gas recirculation parameters, such as frequency and duration, significantly
influenced biogas production rates. However, they also noted that excessive recirculation could lead to increased energy
consumption and potential disruption of microbial communities. The study underscores the importance of balancing gas
recirculation intensity to maximize biogas yield while maintaining system stability.

Figure 10. Venn Diagram of Mono-digestion and Co-digestion Process

On the other hand, waste management, the production of renewable energy, and the decrease of pollutants and greenhouse
gas emissions are all facilitated by the anaerobic digestion of Livestock manure [40]. Anaerobic digestion is limited by a

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number of characteristics of livestock manure, including its high moisture content, high lignocellulosic component, ash
concentration, and low organic load [41]. Furthermore, limited methane synthesis and a high amount of volatile fatty acids
(VFAs) in the effluent can be caused by the suppression of ammonia (NH4+) of high N concentrations in LM. Anaerobic
digestion of NH4+ was often shown to be hindered at values between 1500 and 3000 mg/L [42,43].

Despite these possible organic waste-related parameters for anaerobic digestion, the peculiarities of organic waste need the
adoption of numerous technologies for mono-anaerobic digestion. Anaerobic co-digestion has gained popularity recently
due to its ability to simultaneously digest two or more substrates, which helps it overcome the inhibitory factor of
mono-digestion [43, 44]. By promoting microbial variety, dilution of hazardous and inhibitory chemicals, and nutrient
balance, the anaerobic co-digestion of FW and LM can increase system efficiency [43]. By combining FW with a high
organic content with LM with a high nitrogen content, the anaerobic co-digestion efficiency can be raised by using a
suitable C/N ratio of 20–30 for the co-substrates.

XI.VI. Type of Biodigester Tank

XI.VI.I Floating gas-holder type biogas plant

An underground brick masonry digester with an inlet and an exit covered by a floating steel gas holder for gas collection is
the primary component of this kind of plant. Depending on the buildup and release of gas, the gasholder is guided by a
central guide pipe as it moves up and down. These plants are significantly larger than fixed dome types since the mild steel
floating gas holder alone accounts for around 40% of the entire plant cost. The digester is isolated from the gas holder. The
digester has a barrier to promote circulation. The digester's top has a floating gas container that aids in maintaining a steady
pressure. The digester's top has a floating gas container that aids in maintaining a steady pressure. When the pressure rises
as a result of gas production, the gas holder raises as well, allowing the gas to escape through the gas supply pipe. When the
pressure is reduced to cut off the biogas supply, it descends.

Figure 11. Floating gas-holder type biogas plant. Image from (PDF) Comparison among different models of biogas plants

XI.VI.II. Fixed Dome Type Biogas Plant

The digester and gas holder are combined in a fixed dome digester. The digester's upper section is where gas is kept. Higher
A section of the digester pit itself serves as a holding tank for gases. The necessary pressure for gas discharge is provided
by the displaced level of slurry. Its latter application. As the gas is gathered, the digester's internal pressure changes.
Typically, fixed dome digesters are constructed below ground level and work well in cold climates. Since the plant doesn't
use any steel components, it can be constructed using its construction expenses are modest since it uses local resources.

Figure 12. Fixed-dome type biogas plant. Image from (PDF) Comparison among different models of biogas plants

XI. VI.III. Biobag Digester

The Biobag digester is perfect for rural communities to install themselves because it is easy to build and requires no
knowledge or expertise. To guarantee that the substrate flows under gravity, this digester features two waterproof manholes
(inlet and outflow) at varying depths. The biobag is shaped like a cylinder, and the excavation's bottom is left rounded to
preserve the biobag's rounded shape and facilitate the passage of its contents from the intake to the exit. The amount of
slurry inside the biobag is kept at two thirds of its diameter. The outlet pipe's level in the outlet manhole regulates this level.
Straw or another insulating material, like polystyrene, can be used to cover the Biobag, which is used in Biobag digesters
that run in the mesophilic temperature range. Heating the slurry in the inflow manhole would be the simplest method of

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increasing the temperature. In order to prevent oxygen from entering the digester and inhibiting the anaerobic reaction, it is
crucial to top off the slurry in the inflow manhole with water once the substrate has been fed into the digester's inlet.

Figure 13. Biobag Digester. Image from: Bio Digester Manual 1 | PDF | Biogas | Anaerobic Digestion

XI.VI.IV. EZ-digester
Installing the EZ-digester, a portable, above-ground floating dome digester, is quick and easy. It has been specifically
created for individual household use in both urban and rural communities. This digester has a lifespan of more than ten
years and is made of sturdy roto-molded plastic. Unlike the conventional floating dome digester, which includes a metallic
gasholder, the digester is composed of plastic and is hence impervious to corrosion. Because round excavation is not
required, this digester is also above ground and movable, making it suitable and practical in any area.

Figure 14. EZ-digester. Image from: Benefits B The EZ- Digester Organic waste, Digestate & Appliances n.d.;2.Biogas
digester types installed in South Africa: A review - ScienceDirect

XI.VII Control systems using microcontroller

XI.VII.I. Types of microcontrollers

World has witnessed a remarkable change in Microcontroller technology and various types of Microcontroller generations
have evolved. Starting from 8051 to ARM these days, everything has been changed by microcontrollers. Various
microcontrollers like 8051, PIC, AVR, ARM and ARDUINO along with their various customized boards have come up in
the market and has given researchers and industry to take up and develop wide range of products from daily use to highly
sophisticated and reliable operations (Nayyar, A., 2016).

Recently, the number of applications developed using microcontrollers has increased rapidly. Rapidly evolving
microcontroller technologies now become embedded systems that can do all the work at the same time with single card
computer systems. Many of these open source systems are becoming more and more popular (Güven, Y., et al., 2017).

When choosing a microcontroller development card, a number of features have to be considered such as card interface,
intrinsic hardware, program development interface, operating voltage, input / output numbers as well as processor power
and capacity. In addition, care must be taken to ensure both hardware and software compatibility of the extra equipment
supporting the development board. When choosing a development card, the following must be observed: (Güven, Y., et al.,
2017).

XI.VII.II. Types of arduino devices

Table 11. Types of Arduino devices
Board name Year Microcontroller Board name Year Microcontroller

Diecimila 2007 ATmega168V Mega 2560 2010 ATmega2560

Lilypad 2007 ATmega168V/AT Uno 2010 ATmega328P

mega328V

Nano 2008 ATmega328/ATm Ethernet 2011 ATmega328P

ega168

Mini 2008 ATmega168 Mega ADK 2011 ATmega2560

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Mini Pro 2008 ATmega328 Leonardo 2012 ATmega32U4

Duemilanove 2008 ATmega168/ATm Esplora 2012 ATmega32U4

ega328

Mega 2009 ATmega1280 Micro 2012 ATmega32U4

Flo 2010 ATmega328P Yún 2013 ATmega32U4+

Linino

Figure 15. Mega layout of Arduino boards (Hughes, J. M., 2016).

Figure 16. Arduino hardware-compatible devices (Hughes, J. M., 2016).

Monitoring System Based Micro‐Controller for Biogas Digester

The study of Abdelouareth and Tamali, (2022) proposes an online monitoring system for anaerobic digesters, which
produce methane through waste fermentation. Utilizing open-source hardware and software, the system is built around an
Arduino due to its compact size, affordability, and capability to host data processing algorithms. This setup enables
real-time measurement and control of key parameters within the digester, enhancing process supervision and efficiency.

Implementing such a monitoring system can lead to improved process stability and performance in biogas plants. For
instance, a study on a heating system for high-temperature biogas digesters demonstrated that maintaining a consistent
temperature of 50 ± 2 °C in the digester resulted in a heat recovery rate of up to 70% from the methane liquid. Temperature
control is also important, as high temperatures can result in a decrease in microbial activity, while low temperatures can
slow down the biogas production rate. Similarly, the importance of monitoring and controlling the organic loading rate and
HRT to prevent VFA accumulation and maintain optimal pH levels. The article also suggested the use of alkaline materials
to help stabilize the pH levels in systems with high VFA concentrations (Amoo et. al., 2023).

According to Rasi et al. (2007), the efficiency of biogas production and its energy potential depend on maintaining optimal
conditions within the digester, including temperature, pH, and substrate composition. Monitoring biogas systems is
important to maximize the production of methane yield and keep operations safe. Regular assessment of biogas
composition allows for better control of the anaerobic digestion process and the identification of potential inefficiencies.
Traditional methods of gas analysis which often rely on periodic sampling and laboratory testing that can be
time-consuming and impractical particularly for small-scale applications (Jameel et al., 2024).

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Additionally, integrating Internet of Things (IoT) technologies into biogas plant monitoring systems has been shown to
enhance efficiency. An IoT-based system utilizing an Arduino microcontroller was deployed to measure parameters such as
temperature, pressure, and gas composition, facilitating real-time monitoring and data analysis. The integration of
microcontroller-based monitoring systems in biogas digesters offers a promising approach to optimizing biogas production
through real-time data acquisition and process control.

Lime Water Bubbler

(Li, S., et al., 2023) investigates CO2 bubbling pretreatment to mitigate the inhibitory effects of lime disinfectant
wastewater on anaerobic digestion (AD) of swine manure. Lime disinfectants introduce high calcium ion (Ca²⁺)
concentrations, which disrupt biogas production. Key findings show that CO2 bubbling effectively reduces Ca²⁺ levels and
significantly improves biogas yields, offering a practical and environmentally friendly solution for swine manure AD
systems.
Table 12. CO2 Pretreatment Findings
Category Summary

Calcium Ion Reduction Ca²⁺ concentration reduced by 73.0% after pretreatment.

Biogas Production (Batch Test) Biogas yield increased by 28 times compared to untreated systems.

Biogas Production (Continuous Test) Biogas yield increased by 112.4% in pretreated systems.

Ca²⁺ Stabilization Pretreated systems stabilized at 2.6 g/L, compared to 7.67 g/L in untreated
systems.

Environmental Impact Utilizes CO2 from biogas, reducing greenhouse gas emissions and
promoting carbon neutrality.

Efficiency
Food wastes were separately stored for 0, 1, 2, 3, 4, 5, 7, and 12days, and then fed into a methanogenic reactor for a
biochemical methane potential (BMP) test lasting up to 60days. Relative to the methane production of food waste stored
for 0-1day (285-308mL/g-added volatile solids (VSadded)), that after 2-4days and after 5-12days of storage increased to
418-530 and 618-696mL/g-VSadded, respectively. The efficiency of hydrolysis and acidification of pre-stored food waste
in the methanization reactors increased with storage time. The characteristics of stored waste suggest that methane
production was not correlated with the total hydrolysis efficiency of organics in pre-stored food waste but was positively
correlated with the storage time and acidification level of the waste. From the results, we recommend 5-7days of storage of
food waste in anaerobic digestion treatment plants.Fan Lü, Xian Xu, Liming Shao,Pinjing He (2016).

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XII. Methodology:

Figure 1. CDIO Framework

XII.I Conceive
This study focused on the design and development of a Methane Generation System for Individual Household Using
Residential Food Waste. The design considered the input and output of the study as well as the process and procedures
involved in the operation. The principles of the operation will be included. Figure 1 shows the research paradigm of the
study.

Knowledge Requirement
This study is designed to provide an effective approach, starting with a thorough literature study. This first part This study
is designed to provide an effective approach, starting with a thorough literature study. This first part concentrated on
comprehending the basic ideas of anaerobic digestion, the biochemical mechanisms governing the synthesis of methane,
and the most recent developments in home-scale biogas systems. Key elements influencing methane production, including
pH levels, temperature, retention time, and microbial activity, were identified through an analysis of scientific and technical
publications. In order to direct the design, the evaluation also covered potential hazards, environmental effects, and safety
regulations relevant to small-scale biogas systems.
The wet anaerobic digestion process will be used in the study to assess the effectiveness of a methane generating system.
Food waste with a moisture level of at least 85% that is appropriate for wet digestion will be fed into the system. To
guarantee ideal methane production, critical variables including pH, temperature, and the carbon-to-nitrogen ratio will be
tracked and maintained. With insulation and temperature control devices, the digester will run consistently under
thermophilic conditions (40-55°C). Gas flow meters will be used to measure the amount of biogas produced each day. To
evaluate the overall effectiveness of the system, feedstock retention time as well as digestate volume and composition will
be monitored.

The study will also look into how system performance is affected by changes in feedstock types and operating parameters
like temperature and retention time. The sustainability of the system will be assessed based on environmental variables,
such as overall energy efficiency and waste volume reduction. The study's data will be examined to determine the best
circumstances for producing biogas, and a thorough report on system performance, operational difficulties, and suggestions
for enhancement will be written. This study will shed important light on the viability and efficiency of producing methane
at the home level using the wet anaerobic digestion process.

Flow gauges will be used to track the generation of biogas. The digestate's potential as fertilizer will also be evaluated by
looking at its nutrient content. Environmental effects will be assessed for sustainability, including greenhouse gas
emissions, and energy needs for thermophilic settings. A report with suggestions for improving anaerobic digestion for
food waste management will be created after data analysis comparing biogas outputs, methane content, and process
efficiency.

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The types and amounts of waste appropriate for methane generation were then identified through a comprehensive
evaluation of food waste produced in homes. Typical food waste types were recognized, such as meat scraps, rice
leftovers, fruit scraps, vegetable peels, and small amounts of dairy waste. Based on a local survey in Tiquiwan Rosario,
Batangas the average amount of food waste produced daily per family was estimated to be around 2 - 3kg.

Figure 2. Type of Food Waste in Tiquiwan, Rosario Batangas

Figure 3. Estimated Food Waste per day in Tiquiwan, Rosario Batangas

Furthermore, according to the data, the average daily production of pig manure by each household is approximately 2 kg.
Additionally, it has been observed that most residents of Tiquiwan maintain over 10 pigs on their farms, which makes a
substantial contribution to the region's total manure production. To assess the possible energy production, methane
generation ratios for a variety of food waste types, including pig manure, were looked at. These factors aid in calculating
the quantity of methane that could be trapped and converted into a sustainable energy source that could power farms and
houses while lowering waste and having a minimal negative impact on the environment. The results indicate that the
community has a great deal of potential for producing biogas from organic waste, which would have positive effects on the
environment and the economy.

Figure 4. Estimated number of pigs per household in Tiquiwan, Rosario Batangas

Moreover, the study of existing household-level biogas systems will begin with a comprehensive review of literature,
including research papers, technical reports, and case studies. Considering geographical differences in digester sizes,
feedstock types, and user requirements, this phase will concentrate on finding common designs, parts, and operating
principles of household biogas systems. To create a comprehensive understanding of current systems, important
characteristics such waste management procedures, maintenance needs, and gas collection techniques will be documented.

The performance of current biogas systems will be investigated through field surveys and case studies. Information on
methane content, biogas yield, system performance, and operational difficulties will be gathered through visits to a few
chosen homes. User interviews will shed light on their satisfaction, experiences, and how these solutions affect waste
management and energy conservation. A report with suggestions for enhancing the layout, effectiveness, and
cost-effectiveness of home-level biogas systems will be produced after the results have been examined to determine their
advantages, disadvantages, and best practices.

Environmental and safety considerations will be central to the project. Gas leaks will be monitored and mitigated using
proper sealing techniques, while odor control measures will be implemented to enhance the user experience. The system
will aim to reduce household waste volume by an estimated 80%, contributing to sustainable waste management. Safety

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will be further ensured through compliance with industry standards, including the installation of a gas shutoff valve and the
routine testing of gas purity.

Technical Requirement
The study will evaluate the performance of a methane generation system using the dry anaerobic digestion process. Food
waste with a moisture percentage of 60–85% that is appropriate for wet digestion will be fed into the system. To guarantee
ideal methane production, critical variables including pH, temperature, and the carbon-to-nitrogen ratio will be tracked and
maintained. With insulation and temperature control devices, the digester will run consistently under thermophilic
conditions (50–60°C). Gas flow meters will be used to measure the amount of biogas produced each day, and a gas
chromatograph will be used to measure the amount of methane. Additionally monitored will be the digestate's volume and
composition, as well as the feedstock's retention period.

Operational testing under various situations will be used to assess the methane generating system's dependability and
durability. The system will be operated continuously to evaluate its capacity to sustain steady performance throughout time.
To assess performance stability, important metrics including methane content and biogas yield will be tracked every day.
Any disruptions or faults in the system will be documented in order to pinpoint any areas where the operation or design is
lacking. To assess the system's resistance under harsh circumstances, stress testing will be carried out by subjecting it to
difficult situations including overloading and temperature swings.

By illustrating wear and tear through repeated loading and unloading cycles of food waste feedstock, durability will be
further evaluated. Seals, valves, and pipes are among the parts that will undergo routine inspections for indications of wear,
corrosion, or material deterioration. The frequency of repairs and the parts that need to be replaced frequently will be noted
in maintenance logs. To find failure trends and offer suggestions for enhancing system architecture and material choice, the
gathered data will be examined. The construction of a dependable and long-lasting methane generating system fit for
residential usage will be facilitated by these discoveries.

In terms of availability of raw materials, household surveys and waste audits will be used to determine whether home food
waste is available as a raw material for the methane generating system. Data on food waste creation patterns, including the
kinds, amounts, and frequency of waste generated, as well as current disposal techniques, will be gathered through surveys
carried out in the target area. To guarantee that the data gathered represents the larger community, a representative sample
of households will be used. In order to comprehend any variations in raw material availability throughout the year, seasonal
variations in food waste generation will also be taken into account.

In order to supplement the surveys, waste audits will gather and classify food waste from a subset of households during a
predetermined time frame. To determine the percentage of food waste such as fruit peels, vegetable scraps, and leftovers
suitable for anaerobic digestion, the garbage will be sorted, weighed, and examined. The average amount of food waste
accessible per household and the community's total feedstock potential will be estimated by analyzing the data from both
approaches. These results will inform suggestions for effective collection and segregation as well as assess the viability of
employing household food waste as a sustainable raw material.

XII.II. Design

Figure 5. Overview of the Methane Generation System for Individual Household Using Residential Food Waste and Pig
Manure

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LEGENDS:

1.​ Floating Drum Anaerobic Digester: Primary unit for methane production using the dry method.
2.​ Gas Holder/Frame: Supports the storage and management of biogas produced in the digester, ensuring a steady
supply for usage.
3.​ Inlet Pipe: Introduces food waste into the anaerobic digester.
4.​ Outlet Pipe for Slurry: Discharges liquid byproducts from the digester.
5.​ Gas Outlet (Solenoid Valve): Controls the release of biogas from the digester.
6.​ Control Box: Contains the microcontroller for automation and temperature monitoring.
7.​ DHT22 Temperature and Humidity sensor: Accurately monitors the internal temperature of the digester to
maintain conditions favorable for microbial activity.
8.​ Analog pH Sensor: Measures the acidity or alkalinity of the digester contents to keep the pH within the optimal
range for anaerobic digestion
9.​ Pressure Gauge: Measures the internal pressure of the system.
10.​ Pressure Relief Valve: Releases excess pressure to ensure system safety.
11.​ Heating Coil: Maintains the digester's temperature for optimal microbial activity.
12.​ DC Motor: Power the mixer
13.​ Mixer impeller: Stirs digester contents.
14.​ Biogas Scrubber: Removes impurities using water, limestone, and steel wool.
15.​ MQ2 Gas Sensor: Monitors combustible gases, such as LPG, between the scrubber and gas storage tank
16.​ Gas Volume Meter: Measures the volume of biogas produced, providing data for system performance evaluation.
17.​ Gas Storage:Stores purified biogas for consistent availability and use in household or other applications.
18.​ Pressure Gauge: Monitors the pressure in the gas storage system.
19.​ Lime Water Bubbler: Removes hydrogen sulfide from the biogas for further purification.
20.​ Solenoid Valve: Regulates the flow of gas between components.
21.​ Stove: The final component where the biogas is utilized for cooking or other household energy needs.

In the design stage the system components and the material specifications were considered in the development of a methane
generation system for individual households using food waste and pig manure aiming to optimize biogas production while
maintaining critical parameters such as temperature and pH using a microcontroller and appropriate sensors . We used a
modified floating drum type with a substrate of food waste, pig manure and water mixed in a 2:1:2 ratio because it is a
simple, easily understood operation where the volume of stored gas is directly visible. The gas pressure is constant,
determined by the weight of the gasholder. The construction is relatively easy and the construction mistakes do not lead to
major problems in operation and gas yield. An inlet pipe facilitates the introduction of this mixture into the digester. The
byproducts of digestion, including solid sludge and liquid slurry, are removed through an outlet pipe, providing a
nutrient-rich digestate that can be used as organic fertilizer. The daily substrate input was calculated at 5 kg, distributed as 2
kg food waste, 1 kg pig manure, and 2 kg water.

Calculation of substrate proportions

●​ Daily feedstock input: 5 kg/day
●​ Ratio of food waste:pig manure:water = 2:1:2
Calculation of individual masses:
2
Food waste mass = 2+1+2
𝑥5 = 2𝑘𝑔/𝑑𝑎𝑦
1
Pig manure mass = 2 + 1 + 2 𝑥 5 = 1𝑘𝑔/𝑑𝑎𝑦
2
Water mass = 2 + 1 + 2 𝑥 5 = 2𝑘𝑔/𝑑𝑎𝑦

Based on literature recommendations for thermophilic anaerobic digestion, the hydraulic retention time (HRT) was set at 15
days. The digester volume was calculated as the daily input volume multiplied by the Hydraulic Retention Time (HRT),
yielding a capacity of 75 liters. To account for safety and practical usage, the operating volume of the digester was
considered not to exceed 80% of the total volume of the digester for the accumulation of biogas and slurry increase
allowing a safety margin of 20% due to the volatility of the gas, resulting in a final design capacity of 90 liters with the
height of 0.77m and diameter of 0.39m.

Derivation of total digester volume

Feeding rate (Q)
𝑄 = 𝑓𝑤 + 𝑝𝑚 + 𝑤𝑎𝑡𝑒𝑟
= 2 𝑘𝑔 + 1 𝑘𝑔 + 2𝐿
3
= 5 𝐿𝑖𝑡𝑒𝑟/𝑑𝑎𝑦 = 0. 005 𝑚 /𝑑𝑎𝑦

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Volume of digester (V) (Liter)
𝑉𝑑𝑖𝑔𝑒𝑠𝑡𝑒𝑟 = 𝑄 (𝐻𝑅𝑇)
𝑉𝑑𝑖𝑔𝑒𝑠𝑡𝑒𝑟 = 0. 005 (15)
3
𝑉𝑑𝑖𝑔𝑒𝑠𝑡𝑒𝑟 = 0. 075𝑚 = 75 𝑙𝑖𝑡𝑒𝑟𝑠
Take safety factor 10-30% (20%) (Dupin et al., 2001)
𝑉𝑡𝑜𝑡𝑎𝑙 = 𝑉𝑑𝑖𝑔𝑒𝑠𝑡𝑒𝑟 𝑥 1. 2
𝑉𝑡𝑜𝑡𝑎𝑙 = 0.075 x 1.2
3
𝑉𝑡𝑜𝑡𝑎𝑙 = 0. 09𝑚 = 90 liters

Calculation of Height and Diameter

2
π(𝐷 )
𝑉𝑡 = 4
(𝐻)
Assume height of the digester H equals double of the diameter D (H=2D)
2
π(𝐷 )
𝑉𝑡 = 4
(2𝐷)
2
π(𝐷 )
0. 09 = 4
(2𝐷)
𝐷 = 0. 39𝑚
H = 2D
𝐻 = 2(0. 39) = 0. 77𝑚

The digester tank is constructed using stainless steel, a material chosen for its durability, resistance to corrosion, and ability
to withstand the harsh anaerobic environment. Stainless steel also ensures long-term reliability under the high temperatures
of thermophilic digestion, making it an ideal choice for this system. The tank is cylindrical in shape to facilitate efficient
heat distribution of a heating coil to ensure consistent temperature maintenance. The heating coil is connected to a
microcontroller, which automates temperature regulation based on real-time feedback from a DHT22 temperature and
humidity sensor. This sensor is strategically positioned near the digester's top, where temperature fluctuations most directly
impact anaerobic digestion. It accurately measures temperatures ranging from -40°C to 80°C and provides digital data to
the control system. To protect the DHT22 from direct exposure to moisture and organic material, it is enclosed in a durable,
waterproof casing. The integration of the heating coil and temperature sensor with the microcontroller ensures precise
temperature control, enhancing the efficiency and stability of the biogas production process. Additionally, an analog pH
sensor ensures that the acidity remains within the ideal range of 6.0–8.5.

The generated biogas is collected and stored in the floating drum gas holder, which rises and falls to indicate the amount of
gas available. The floating drum, which is responsible for storing the biogas produced, is made from high-density
polyethylene (HDPE). HDPE is lightweight, corrosion-resistant, and compatible with the biogas environment, providing an
economical yet durable solution for the drum. The floating drum is designed to have a volume 1.2 times the expected daily
biogas production. The biogas yield of food waste was estimated at 0.072 m³/day and for pig manure it was at 0.0096
m³/day with a total of biogas yield at 0.1152 m³/day, resulting in a required floating drum capacity of 0.09792 m³. The drum
is designed to float freely on the slurry and rises as biogas is produced, accumulating gas without overpressurizing the
system. Guide rails and a water seal are incorporated to ensure smooth vertical movement of the drum, preventing gas
leakage. A pressure gauge and pressure relief valve are integrated to monitor and regulate internal pressure, ensuring safety.
A control box automates system functions, incorporating a timer, contractor, and various sensors to streamline operations
and monitor key parameters

Volatile Solid:
𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑉𝑆 = 5𝑘𝑔 × 0. 9 = 4. 5𝑘𝑔 𝑉𝑆/𝑑𝑎𝑦
3 4.5 3
𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝑉𝑆 𝑝𝑒𝑟 𝑚 (𝐶𝑣𝑠) = 0.075
= 60 𝑘𝑔 𝑉𝑆/𝑚
Organic Loading Rate:
(𝑄)(𝐶𝑣𝑠) (0.005)(60) 3
𝑂𝐿𝑅 = 𝑉𝑟𝑒𝑎𝑐𝑡𝑜𝑟
= 0.075
= 4𝑘𝑔 𝑉𝑆/𝑚

Expected gas production:

Gas production rate (G)
𝐺𝑓𝑤 = 𝑂𝐿𝑅 × 𝑉𝑆 × 𝑔𝑎𝑠 𝑝𝑟𝑜. 𝑅𝑎𝑡𝑒 (𝑚3/𝑘𝑔 𝑉𝑆)
3
𝐺𝑓𝑤 = 4 × 0. 06 × 0. 44 According to (Dorgham, 2022), 1kg of food waste yields 0.44𝑚 biogas if well digested.
3
𝐺𝑓𝑤 = 0. 1056 𝑚 /𝑑𝑎𝑦

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3
𝐺𝑝𝑚 = 4 × 0. 06 × 0. 04 According to (Babbo, 2023), 1 kg of pig manure yields 0. 04 𝑚 biogas if well digested.
3
𝐺𝑝𝑚 = 0.0096 𝑚 /𝑑𝑎𝑦

Total Gas Production

𝐺𝑇 = 𝐺𝑓𝑤 + 𝐺𝑝𝑚 (5)
𝐺𝑇 = 0. 1056 + 0.0096
3
𝐺𝑇 = 0. 1152 𝑚 /𝑑𝑎𝑦
Volume of Floating Drum:

𝑉𝑑𝑟𝑢𝑚 = 𝐺𝑇 × safety factor

𝑉𝑑𝑟𝑢𝑚 = 0.1152 × 1.2
3
𝑉𝑑𝑟𝑢𝑚 = 0. 13824 𝑚 = 138.24 liters

Before use, the raw biogas undergoes purification. A biogas scrubber removes impurities such as hydrogen sulfide (H₂S)
and carbon dioxide (CO₂) using water, limestone, and steel wool. To ensure safe operation, a MQ2 gas sensor is installed
between the scrubber and gas storage tank to monitor combustible gases, such as LPG. This sensor continuously measures
gas composition, enhancing the system’s safety by providing real-time feedback. Solenoid valves are used to control the
flow of biogas between components, ensuring smooth operation and preventing leaks. After purification, the biogas is
stored in a gas storage tank, monitored by a pressure gauge to maintain safe and stable conditions.

Additionally, a gas volume meter is integrated to measure the total volume of biogas produced. The gas volume meter is
placed in-line with the hose, positioned after the scrubber but before the gas storage tank. This setup ensures that both the
quality and quantity of biogas are effectively monitored, maintaining the system’s efficiency and safety. Once purified, the
biogas is delivered through the gas outlet to household stoves for cooking. The system produces approximately 0.64 cubic
meters of biogas daily, sufficient to power cooking activities for 1–3 hours.

XII.IV. Controlling Units

Heating Unit
To keep the digester's internal temperature within the thermophilic range (43–55°C), the researchers will employ a heating
coil as a heat exchanger. To heat the slurry directly, the heating coil inside the digester needs to be coiled.

Figure 6. Heating Coil

Mixing Unit
For mixing inside the digester, a DC motor with a low rotation speed of 67 rpm will be employed. To guarantee complete
area mixing, the motor was mounted in the digester's bottom and connected by a shaft with two central blades at two
different heights.

Figure 7. Mixing Unit

As stated by Tortwa and Ji (2018), an electric mixer with a capacity of 220 V, 50 Hz, 1050 W, and six adjustable speeds
ranging from 100 to 600 rpm was used to operate the impellers. The impellers were made of SUS304 steel and were open
left-hand (LH) types with a blade thickness of 2.5 mm, a diameter of 0.180 m (T/D = 0.5), and were positioned 60 mm
above the liquid's bottom surface.

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Figure 8. DC Motor

Hence, the researchers will use higher mixing intensity of 67 rpm applied for 5 minutes per hour that will result in a
15–18% increase in biogas production compared to lower intensities of 10 rpm and 30 rpm as mentioned in this study. This
enhancement was achieved without causing instability, as evidenced by the absence of volatile fatty acid (VFA)
accumulation and the elimination of dead zones. VFAs are intermediates in the digestion process, and their uncontrolled
accumulation can inhibit methanogenesis. Thus, maintaining a uniform shear rate through effective mixing can serve as a
valuable tool for ensuring process stability and maximizing methane yields (Singh et al., 2021).

XII.V. Automatic Control System

In order to maximize biogas production and make it simple and secure for everyone to use at home in its current form, the
researchers will create an automated control system to regulate AD settings. The control system employed a few sensors to
monitor the temperature of the gas and the material, modify the mixing time, estimate the amount of gas and any leaks,
regulate the process temperature, and perform a few other functions.

XII.V.I. Microcontroller
The system will use Arduino Uno to serve as the central control unit for monitoring the methane generation system. It will
be used to collect and process data from sensors integrated into the system, such as temperature, pH, and gas production
sensors. These sensors will ensure that the anaerobic digestion process operates within optimal conditions, maintaining a
stable environment for efficient biogas production. The Arduino Uno will also enable the system to execute automated
actions, such as triggering heating elements or adjusting input ratios, based on the data collected. Furthermore, its
compatibility with various communication modules allows for the development of a user-friendly interface, potentially
through a desktop to provide users with accessible updates on system performance. By leveraging the Arduino Uno's
versatility, the system ensures a robust and cost-effective solution for household-level biogas production, aligning with the
project’s objectives of sustainability and efficiency. The arduino Uno is used as it is a cost-effective tool that can be used in
our process.

Figure 9. Arduino Uno

XII.V.II. DHT22 Temperature and Humidity sensor

The DHT22 is a digital temperature and humidity sensor that measures temperature using a thermistor and a capacitive
humidity sensor. The analog readings are transformed into a digital signal by an internal chip. Temperatures between -40°C
and 80°C are measured by it. A microcontroller can read the DHT22's digital output directly, disregarding the need for
further signal processing or amplifiers. The DHT22 sensor will be positioned inside the digester or very near the top, where
the anaerobic digestion process is immediately impacted by temperature and humidity levels. To keep DHT22 safe from
moisture exposure and direct contact with trash, the researchers will make sure it is enclosed in a protective shell or casing.

Figure 11. DHT22 Temperature and Humidity sensor

XII.V.IV. MQ2 Gas Sensor
The MQ2 gas sensor was selected to monitor the concentration of LPG in parts per million (ppm). This sensor features a
heater coil and resistance, which change their values in response to variations in gas concentration. The Arduino Mega
interfaces with the sensor by measuring the resistance using a voltage divider method.

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Figure 12. MQ2 Gas Sensor

XII.V.V. Analog pH Sensor
The analog pH sensor is used to measure the acidity or alkalinity of the digester contents in the methane generation system.
Maintaining the pH within an optimal range (typically 6.0–8.5) is crucial for efficient anaerobic digestion. Fluctuations in
pH levels can impact the activity of microorganisms involved in the breakdown of organic matter.

Figure 13. Analog pH Sensor

XII.V.VI. LCD (Liquid Crystal Display)

The LCD is utilized to display gas, material temperature, and gas concentration within the tank. With two lines, the 16x2
screen can display up to 16 characters per line. An LCD will function as the system's user interface. Without requiring a
computer connection, it will show the data from many sensors, including temperature, pH, methane concentration, and
others, allowing the operator to easily keep an eye on the system's condition. The LCD will be positioned so that the user
may readily read it in a safe and visible area. Arduino displays letters on this display using the IIC communication protocol.

Figure 14. Liquid Crystal Display (16X2)

XII.V.VII. Relay
A relay will be used as a switch controlled by the microcontroller to open and close the circuit of the heating coil.
Solid-state relay has higher reliability, and faster switching especially if you are dealing with high-voltage AC circuits.
Relay should be matched to the voltage and current requirements of the heating coil, and always prioritize safety when
handling high-voltage components.

Figure 15. Solid State Relay

XII.V.VIII. Control Box
The Arduino board and all of the automatic control system's parts were placed in a control box with a power button for the
entire system, including the data that shows on the LCD, and a system button for the control units. The control box will
serve as the housing and protect the electrical components, such as microcontroller, relay, sensors, heating coil, and other
circuit components. The control box ensures that all components are neatly organized, properly protected from
environmental factors, and easy to operate and maintain.

Figure 15. Control Box

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Figure 6. Block Flow Diagram for Anaerobic Process

As shown in figure 6 the anaerobic digestion process begins through collection of the inputs such as water (2L), food waste
(FW)(2KG) and pig manure (PM) (1KG) daily and it undergoes through four biological stages. During hydrolysis, large
organic molecules are broken down into simpler compounds like sugars, amino acids, and fatty acids. In acidogenesis,
these compounds are further converted into volatile fatty acids, alcohols, hydrogen, and carbon dioxide. The process
continues with acetogenesis, where fatty acids are broken down into acetic acid, hydrogen, and carbon dioxide. Finally, in
methanogenesis, methane (CH₄) and carbon dioxide (CO₂) are produced, forming the biogas. The amount of biogas
produced consists of 60-80% of methane, 20-40% of carbon dioxide, and a few amounts of hydrogen sulfide (0.5%),
nitrogen (1%) and 1% of hydrogen.

Figure 7. Temperature Control Block Flow Diagram for Biogas Production using Food Waste and Pig Manure

Figure 7 entails the Temperature Control Block Flow Diagram for Biogas Production using Food Waste and Pig
Manure.To maintain the intended setpoint temperature of 45°C, the anaerobic digester's temperature control system
functions as a closed-loop feedback system. An error signal is produced by comparing the desired temperature with the
actual temperature obtained from a temperature sensor at a summing junction. An Arduino Uno processes this error signal
and determines the proper control signal to modify the digester's heating coil. The ideal conditions for anaerobic digestion
are ensured by the heating coil, which adjusts the temperature as necessary. The process may be impacted by outside
disruptions such changes in feedstock or ambient temperature. The feedback loop ensures that the digester operates
consistently and efficiently by continuously monitoring the actual temperature and sending it back to the controller to
adjust deviations from the setpoint.

Figure 8. pH Control Block Flow Diagram for Biogas Production using Food waste and Pig manure

The pH level of an anaerobic digester is kept at the setpoint of pH 7.0 by this closed-loop control system. In order to
generate an error signal, the system first compares the reference input (pH 7.0) with the actual pH as determined by a pH
sensor. Disturbances, such as changes in feedstock composition or buffering capacity, can affect the system, but the
feedback loop continuously monitors the pH and corrects deviations, ensuring stable operating conditions. The manipulated

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variable, pH adjusting solution is added to the digester to correct the pH. The Arduino Uno, programmed as a PID
controller, processes the error and determines the necessary chemical dosage, acid or base to correct the pH.

This system ensures that the controlled variable (6.8-7.5) remains stable within the desired range, providing an optimal
environment for microbial activity and maintaining process efficiency..

Figure 9. Process Flow Chart

Figure 9 shows the process flow chart flow biogas production using food waste and pig manure. The process of producing
biogas from food waste begins with the collection of input such as food waste, pig manure and water. Once collected, the
food waste undergoes an initial sorting step to ensure that it is free from non-organic contaminants like plastics and metals,
which cannot be processed in the anaerobic digestion stage. The next key process is anaerobic digestion, where the sorted
and shredded food waste is broken down by microorganisms in the absence of oxygen. This process takes place in a
bioreactor, a sealed chamber designed to maintain the anaerobic environment. The digestion of organic waste produces
biogas, primarily composed of methane (CH₄) and carbon dioxide (CO₂). Once the anaerobic digestion process is complete,
the biogas is stored in a tank or storage system for later use.

Before the biogas is used for energy generation, it is essential to verify whether there is a sufficient amount available. If
there is enough biogas, it is utilized for energy production, such as electricity or heat, which can either be used on-site or
distributed to the grid. If the amount of biogas produced is insufficient, the system may need to wait for additional biogas to
be generated.The leftover material from the anaerobic digestion process, called digestate, is a nutrient-rich organic matter
that can be used as compost or a soil conditioner. This step adds value to the process, as the digestate can be used to
improve soil health, contributing to sustainable agricultural practices. Once the biogas has been used and the digestate is
processed, the biogas production cycle is complete, marking the end of the process.

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Figure 10. Process Flow Chart for Anaerobic Digestion

Figure 10 illustrates the process flow chart for anaerobic process of the system for biogas production using food waste and
pig manure. Anaerobic Digestion process begins to feed (fw, pm and water).Clean waste is then fed into the anaerobic
digester, a sealed container where microorganisms break down the material in the absence of oxygen.

The digestion process occurs in four stages. First is hydrolysis, where large organic molecules are broken down into
simpler compounds like sugars, amino acids, and fatty acids. Next, during acidogenesis, these compounds are converted
into volatile fatty acids, alcohols, hydrogen, and carbon dioxide. In acetogenesis, the fatty acids are further broken down
into acetic acid, hydrogen, and carbon dioxide. Finally, in methanogenesis, methanogenic microorganisms produce methane
(CH₄) and carbon dioxide (CO₂), which make up biogas. Once the digestion process is complete, the system checks if
enough biogas has been produced. If not, the process continues to allow further biogas production. If sufficient biogas is
ready, it is collected and used as a renewable energy source for electricity generation, heating, or cooking. Meanwhile, the
by-products of digestion, known as digestate, are processed.

Software Requirement
In the design and layout of the biogas system several software tools are essential for both physical and logical system
development. CAD software, like AutoCAD or SolidWorks, is used to create detailed floor plans and 3D models of the
biogas plant, positioning key equipment for optimal efficiency. Modeling and simulation tools such as MATLAB/Simulink
and Aspen Plus help predict biogas production and optimize the anaerobic digestion process by simulating the system's
behavior under different conditions.

For the logical design, data flow diagrams and system interaction diagrams created with Lucidchart or Visio visualize how
data moves through the system. Software like Python or LabVIEW manages sensor data, enabling operators to monitor
biogas production and control the system remotely. A database management system such as MySQL or PostgreSQL stores
important data like waste input and gas production, helping optimize operations and ensure long-term system efficiency.

XII.III Implement

Fabrication of the system

The fabrication process for the methane generation system focused on crafting and assembling the necessary components to
ensure functionality and durability. The process began with the construction of the digester tank, gas collection unit, and
control system housing, all designed according to the system’s specifications. Cost-effective yet durable materials were
selected to enhance system performance and reliability, keeping in mind the limited resources available to students, Each
component will carefully be inspected to ensure they meet the required standards.

After the fabrication, the components will be systematically assembled into a cohesive system. The digester tank was
connected to the feedstock input unit, while the gas collection unit was integrated to capture and store biogas. Sensors for
monitoring key parameters such as temperature and pH were installed, along with safety mechanisms like solenoid and
globe valves, as well as leak-proof connections. A preliminary dry run will be conducted to assess the mechanical and

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electrical systems, followed by a trial with simulated feedstock to verify initial biogas production and system
responsiveness.

Final Testing
The final testing phase evaluated the overall performance and efficiency of the methane generation system. The
system will operate continuously for a minimum of 10-15 days using actual food waste and pig manure as feedstock.
During this period, biogas samples were collected daily to measure methane content and calculate production rates.

Percentage of Food Waste to Biogas:

This refers to the ratio of food waste input to the amount of biogas produced by the system. To evaluate the efficiency of
the anaerobic digestion process. A higher percentage refers to more biogas produced from the same amount of food waste.

Formula:
3
𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝐵𝑖𝑜𝑔𝑎𝑠 𝑃𝑟𝑜𝑑𝑢𝑐𝑒𝑑 (𝑚 )
Percentage of Food waste to biogas = 𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝐹𝑜𝑜𝑑 𝑊𝑎𝑠𝑡𝑒 𝑢𝑠𝑒𝑑 (𝑘𝑔)
𝑥 100

3
0.1056 𝑚
Percentage of FW = 2𝑘𝑔
𝑥 100 = 5.28 %
Therefore, 5.28% of the food waste has been converted into biogas.

Number of Cooking Hours :

This refers to the measured metric on how long the biogas is produced by the system for cooking purposes. It aids to
determine the practicality and sustainability of the system in terms of daily household use.

Formula:

3
𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝐵𝑖𝑜𝑔𝑎𝑠 𝑃𝑟𝑜𝑑𝑢𝑐𝑒𝑑 (𝑚 )
Cooking Hours = 3 𝑥 100
𝐺𝑎𝑠 𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛 𝑅𝑎𝑡𝑒 𝑜𝑓 𝑆𝑡𝑜𝑣𝑒 (𝑚 /ℎ𝑜𝑢𝑟)

0.1152
Cooking Hours = 0.2
= 0. 576 ℎ𝑜𝑢𝑟𝑠 𝑜𝑟 34. 56 𝑚𝑖𝑛𝑢𝑡𝑒𝑠.

Reduction in Food Waste:

This refers to how much food waste is diverted from landfills and converted into valuable biogas and fertilizer. It
demonstrates the environmental impact of the system.

Formula:

𝐴𝑚𝑜𝑢𝑛𝑡 𝑜𝑓 𝐹𝑜𝑜𝑑 𝑊𝑎𝑠𝑡𝑒 𝐷𝑖𝑣𝑒𝑟𝑡𝑒𝑑 𝑡𝑜 𝐵𝑖𝑜𝑔𝑎𝑠 (𝑘𝑔)

Reduction in Food Waste (%) = 𝑇𝑜𝑡𝑎𝑙 𝐹𝑜𝑜𝑑 𝑊𝑎𝑠𝑡𝑒 𝐺𝑒𝑛𝑒𝑟𝑎𝑡𝑒𝑑 (𝑘𝑔)
𝑥 100

2𝑘𝑔
Reduction in Food Waste (%) = 3 𝑘𝑔
𝑥 100 = 66. 67 %

Cost Savings (Reduction in LPG Use):

This refers to the amount of money saved by a household from the reliance on LPG by switching to biogas produced by
the system.

Formula:

𝐿𝑃𝐺 𝑆𝑎𝑣𝑖𝑛𝑔𝑠
Cost Savings (%) = 𝑇𝑜𝑡𝑎𝑙 𝐿𝑃𝐺 𝐶𝑜𝑛𝑠𝑢𝑚𝑝𝑡𝑖𝑜𝑛
𝑥 100

500
Cost Savings (%) = 1000
𝑥 100 = 50%

Biogas Production Efficiency:

This refers to how efficient the system is, in converting organic waste into biogas.

Formula:

𝐸𝑛𝑒𝑟𝑔𝑦 𝑃𝑟𝑜𝑑𝑢𝑐𝑒𝑑 𝑓𝑟𝑜𝑚 𝐵𝑖𝑜𝑔𝑎𝑠 (𝑘𝑊ℎ)

Biogas Production Efficiency = 𝐼𝑛𝑝𝑢𝑡 𝑂𝑟𝑔𝑎𝑛𝑖𝑐 𝑊𝑎𝑠𝑡𝑒 (𝑘𝑔)

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If the system produces 0.1152 cubic meters of biogas daily, and 1 cubic meter of biogas equals 6.1 kWh, the system
produces:

3 3
0. 0186 𝑚 𝑥 6. 1 𝑘𝑊ℎ/𝑚 = 0. 70 𝑘𝑊ℎ

System Reliability and Maintenance:

This refers to how frequent the system needs maintenance and how reliable it is over time.

Formula:
𝑡
= 𝑀𝑇𝐵𝐹
Reliability (%) = 𝑅(𝑡) = 𝑒

Where:

●​ R(t) = Reliability at time t (probability that the system will not fail at time t).
●​ t = Time period
●​ MTBF (Mean Time Between Failures) is the average time the system operates without failure.
●​ MTTR (Mean Time to Repair) is the average time taken to restore the system after a failure.

Let’s assume:

●​ MTBF = 5000 hours (this is the average time the system operates before failure).
●​ MTTR = 10 hours (this is the average time taken to repair the system after failure).

For a 1-month period (30 days or 720 hours)

720
− 5000 =0.144
R(t) = 𝑒 =𝑒 = 0. 866 × 100 = 86. 6%

This means the system has an 86.6% reliability over a 1-month period, meaning there is an 86.6% chance that the system
will operate without failure during that period.

To sum this up, this system is an effective and efficient way to generate energy and manage garbage in a sustainable way. In
addition to keeping 66.67% of food waste out of landfills, turning it into biogas lessens its environmental impact by giving
cooks a clean energy source. The system is both economically advantageous and environmentally benign, offering
substantial cost savings, 50% reduction in LPG consumption, and the capacity to light a stove for 34 minutes each day with
a 5.28% food waste conversion rate to biogas. Its 0.70 kWh of energy generation per day shows strong biogas efficiency,
and its 86.6% reliability rate guarantees long-term operating stability with no maintenance, making it a dependable,
affordable, and environmentally responsible option for homes.
XIII. Duties and Responsibilities of each member:

Student 1 - Araja, John Erasmouz Marie - Project Lead

●​ Editing and Revisions of the paper

●​ Literature Review
●​ Statistical Analysis
●​ System Hardware Integration
●​ Material Selection

Student 2 - Briñes, Christine Joy N.

●​ Editing and Revisions of the paper

●​ Literature Review
●​ Expert Consultations
●​ Budgeting and Resource Allocation
●​ Software Development and Debugging

Student 3 - De La Rama, Princess Aira

●​ Editing and Revisions of the paper

●​ Budgeting and Resource Allocation
●​ Literature Review

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●​ Sensor Calibration

Student 4 - Elomina, Alvin Jr. A.

●​ Sensor Calibration
●​ Editing and Revisions of the paper
●​ Literature Review
●​ System Hardware Integration
●​ Material Compatibility Testing

Student 5 - Enriquez, John Lloyd L

●​ Gap Analysis
●​ Literature Review
●​ Technical Documents
●​ Documentation
●​ Prototype Refinement and Iteration
XIV. Major Activities/Work Plan (Gantt Chart): See attached Form A
XV. Line-Item Budget: See attached Form B
1.​ Maintenance and Operating Expenses
2.​ Capital Outlay and Equipment Php 38, 769
XVI. References: IEEE referencing style

M. K. Jameel et al., “Biogas: Production, properties, applications, economic and challenges: A review,” Results in Che
[1] vol. 7, p. 101549, Jan. 2024, doi: https://doi.org/10.1016/j.rechem.2024.101549.
F. Alfarjani, “Design and Optimization of Process Parameters in Biogas Production Systems,” 2012. Accessed: Dec.
[2] [Online]. Available: https://doras.dcu.ie/16807/1/my_thesis__final__2012.pdf
[3] Yang L., Xumeng G., Wan C., Yu F., Li Y. “Progress and perspectives in converting biogas to transportation fuels,” R
and Sustainable Energy Reviews, vol. 40, pp. 1133–1152, Dec. 2014, doi: https://doi.org/10.1016/j.rser.2014.08.008.
[4] S. Siddharth, “green energy-anaerobic digestion,” 2006, heat transfer, thermal engineering and environment, co
pp276- 280, Elounda, Greece. Accessed: Dec. 23, 2024. [Online]. Available: Microsoft Word - 538-110.doc
Ye J, et al. Improved biogas production from rice straw by co-digestion with kitchen waste and pig manure. Waste
[5] 2013;33(12):2653–8 .
[6] Ošlaj M, Muršec B. Biogas as a renewable energy source. Teh Vjesn 2010;17:109.
Braun R, Weiland P, Wellinger A. Biogas from energy crop digestion. IEA Bioenergy Task 2008;37:1–20.
[7]
[8] Jingura RM, Kamusoko R. Methods for determination of biomethane potential of feedstocks: a review. Biofu
2017;4(2):573–86.

[9] Yu L, Yaoqiu K, Ningsheng H, Zhifeng W, Lianzhong X. Popularizing household scale biogas digesters for rural su
energy development and greenhouse gas mitigation. Renew Energy 2008;33:2027–35.
Chen Y, Yang G, Sweeney S, Feng Y. Household biogas use in rural China: a study of opportunities and constraint
[10] Sustain Energy Rev 2010;14: 545–9.
Khoiyangbam RS. Environmental implications of biomethanation in conventional biogas plants. Iranica J Energy
[11] 2011;2:181–7.

Niu, Qigui, "Microbial community shifts and biogas conversion computation during steady, inhibited and recovered
[12] thermophilic methane fermentation on chicken manure with a wide variation of ammonia.” Bioresource technology 14
223-233.
KumarA, Samadder SR. A review on technological options of waste to energy for effective management of munici
[13] waste. Waste Manag 2017;69: 407e22.
[14] Zhang C, Su H, Baeyens J, Tan T. Reviewing the anaerobic digestion of food waste for biogas production. Renew
Energy Rev 2014;38:383e92.
Ahmadi-Pirlou M, Ebrahimi-Nik M, Khojastehpour M, Ebrahimi SH. Mesophilic co-digestion of municipal solid w
[15] sewage sludge: effect of mixing ratio, total solids, and alkaline pretreatment. Int Biodeterior Biodegrad 2017;125:97e1
[16] Appels L, Baeyens J, Degreve J, Dewil R. Principles and potential of the anaerobic digestion of waste-activated slud
Energy Combust Sci 2008;34(6):755e81.

Tracking No.________________​ ​ ​ ​ ​ ​ ​ ​ ​ Page 35 of 39

​ ​
Komilis D, Barrena R, Grando RL, Vogiatzi V, Sanchez A, Font X. A state of the art literature review on anaerobic dig
[17] food waste: influential operating parameters on methane yield. Rev Environ Sci Biotechnol 2017: 1e14.
Esposito G, Frunzo L, Giordano A, Liotta F, Panico A, Pirozzi F. Anaerobic co digestion of organic wastes. Rev En
[18] Biotechnol 2012;11(4):325e41.
[19] S. Mirmohamadsadeghi, K. Karimi, M. Tabatabaei, and M. Aghbashlo, “Biogas production from food wastes:
A review on recent developments and future perspectives,” Bioresource Technology Reports, vol. 7, p. 100202,
Sep. 2019, doi: https://doi.org/10.1016/j.biteb.2019.100202.
[20] R. Chandra, H. Takeuchi, and T. Hasegawa, “Methane production from lignocellulosic agricultural crop wastes: A revi
context to second generation of biofuel production,” Renewable and Sustainable Energy Reviews, vol. 16, no. 3, pp. 14
Apr. 2012, doi: https://doi.org/10.1016/j.rser.2011.11.035.
C. Mao, Y. Feng, X. Wang, and G. Ren, “Review on research achievements of biogas from anaerobic digestion,” Renew
[21] Sustainable Energy Reviews, vol. 45, pp. 540–555, May 2015, doi: https://doi.org/10.1016/j.rser.2015.02.032.
[22] Y. Zhang and C. J. Banks, “Impact of different particle size distributions on anaerobic digestion of the organic fraction
municipal solid waste,” Waste Management, vol. 33, no. 2, pp. 297–307, Feb. 2013, doi:
https://doi.org/10.1016/j.wasman.2012.09.024.
J. Mata-Alvarez, “Biomethanization of the Organic Fraction of Municipal Solid Wastes,” Water Intelligence Online, v
[23] 0, p. 9781780402994-9781780402994, Dec. 2015, doi: https://doi.org/10.2166/9781780402994.

[24] C. Liu, W. Wang, N. Anwar, Z. Ma, G. Liu, and R. Zhang, “Effect of Organic Loading Rate on Anaerobic Digestion of F
Waste under Mesophilic and Thermophilic Conditions,” Energy & Fuels, vol. 31, no. 3, pp. 2976–2984, Feb. 2017, doi
https://doi.org/10.1021/acs.energyfuels.7b00018.
[25] A. Demirbas, “Biofuels securing the planet’s future energy needs,” Energy Conversion and Management, vol. 50, no. 9
2239–2249, Sep. 2009, doi: https://doi.org/10.1016/j.enconman.2009.05.010.
[26] Jain S, Jain S, Tim I, Lee J, Wah Y. A comprehensive review on operating parameters and different pretreatment metho
for anaerobic digestion of municipal solid waste. Renew Sustain Energy Rev 2015;52
https://doi.org/10.1016/j.rser.2015.07.091.
[27] KumarA, Samadder SR. A review on technological options of waste to energy for effective management of munici
waste. Waste Manag 2017;69: 407e22.
[28] Komilis D, Barrena R, Grando RL, Vogiatzi V, Sanchez A, Font X. A state of the art literature review on anaerobic dig
food waste: influential operating parameters on methane yield. Rev Environ Sci Biotechnol 2017: 1e14.
[29] Ahmadi-Pirlou M, Ebrahimi-Nik M, Khojastehpour M, Ebrahimi SH. Meso philic co-digestion of municipal solid w
sewage sludge: effect of mixing ratio, total solids, and alkaline pretreatment. Int Biodeterior Bio degrad 2017;125:97e1
[30] Chen Y, Cheng JJ, Creamer KS. Inhibition of anaerobic digestion process: a review. Bioresour Technol 2008;99(10):40
Lin L, Xu F, Ge X, Li Y. Improving the sustainability of organic waste management practices in the food-energy-water
[31] comparative review of anaerobic digestion and composting. Renew Sustain Energy Rev 2018;89: 151e67.
Arelli V, Begum S, Anupoju GR, Kuruti K, Shailaja S. Dry anaerobic Co digestion of food waste and cattle manure:
[32] total solids, substrate ratio and thermal pre-treatment on methane yield and quality of biomanure. Bioresource Tec
2018.
Nizami AS, Murphy JD. What type of digester configurations should be employed to produce biomethane from gras
[33] Renew Sustain Energy Rev 2010;14(6):1558e68.
[34] An D, Wang T, Zhou Q, Wang C, Yang Q, Xu B, Zhang Q. Effects of total solids content on performance of sludge m
anaerobic digestion and dewaterability of digested sludge. Waste Manag 2017;62:188e93.
[35] Zhang J, Loh KC, Lee J, Wang CH, Dai Y, Tong YW. Three-stage anaerobic co digestion of food waste and horse ma
Rep 2017;7(1):1269.
[36] “Comparison of biogas technologies,” RENERGON - ANAEROBIC DIGESTION, Jun. 01,
https://www.renergon-biogas.com/en/comparison-wet-dry-anaerobic-digestion
[37] L. Luo and N. Pradhan, “Anaerobic mono-digestion and co-digestion of food waste and mixed sewage sludge: A com
analysis of metabolic patterns and taxonomic profiles,” Chemical Engineering Journal, vol. 489, p. 151397, Apr. 2
https://doi.org/10.1016/j.cej.2024.151397.
[38] Pilarska, A.A.; Kulupa, T.; Kubiak, A.; Wolna-Maruwka, A.; Pilarski, K.; Niewiadomska, A. Anaerobic Digestion of F
Waste—A Short Review. Energies 2023, 16, 5742.
[39] ]Li, Y.; Zhang, S.; Chen, Z.; Ye, Z.; Lyu, R. Multi-omics analysis unravels effects of salt and oil on substan ce transform
microbial community, and transcriptional activity in food waste anaerobic digestion. Bioresour. Technol. 2023, 387, 129
Yao, Y.; Huang, G.; An, C.; Chen, X.; Zhang, P.; Xin, X.; Shen, J.; Agnew, J. Anaerobic digestion of livestock manure i
[40] regions: Technological advancements and global impacts. Renew. Sustain. Energy Rev. 2020, 119, 109494.
Kadam, R.; Jo, S.Y.; Lee, J.H.; Khanthong, K.; Jang, H.W.; Park, J.G. A Review on the Anaerobic Co-Digestion of Liv
[41] Manures in the Context of Sustainable Waste Management. Energies 2024, 17, 546.

Tracking No.________________​ ​ ​ ​ ​ ​ ​ ​ ​ Page 36 of 39

​ ​
Speece, R.E. Anaerobic Biotechnology and Odor/Corrosion Control for Municipalities and Industries; Archae Press: N
[42] TN, USA, 2008; pp. 456–458.
Karki, R.; Chuenchart, W.; Surendra, K.C.; Shrestha, S.; Raskin, L.; Sung, S.; Hashimoto, A.; Khanal, S.K. Anaerobic
[43] co-digestion: Current status and perspectives. Bioresour. Technol. 2021, 330, 125001.

Cheng, H.; Qin, H.; Li, Y.; Guo, G.; Liu, J.; Li, Y. Comparative study of high-performance mesophilic and thermophilic
[44] anaerobic membrane bioreactors in the co-digestion of sewage sludge and food waste: Methanogenic performance and
recovery potential. Sci. Total Environ. 2024, 912, 169518
[45] “Manure digestion for biogas from cow/pig/chicken manure - Gazpack,” Mar. 17, 2021.
https://gazpack.nl/en/biogas-from-cow-dung-pig-and-chicken-manure/
C. Dennehy et al., “Anaerobic co-digestion of pig manure and food waste; effects on digestate biosafety, dewaterab
[46] microbial community dynamics,” Waste Management, vol. 71, pp. 532–541, Jan. 2018
https://doi.org/10.1016/j.wasman.2017.10.047.
H. Tian, N. Duan, C. Lin, X. Li, and M. Zhong, “Anaerobic co-digestion of kitchen waste and pig manure with different
[47] ratios,” Journal of Bioscience and Bioengineering, vol. 120, no. 1, pp. 51–57, Jul. 2015, doi:
https://doi.org/10.1016/j.jbiosc.2014.11.017.
M. Ferdeș, B. Ș. Zăbavă, G. Paraschiv, M. Ionescu, M. N. Dincă, and G. Moiceanu, “Food Waste Management fo
[48] Production in the Context of Sustainable Development,” Energies, vol. 15, no. 17, p. 6268, Aug. 20
https://doi.org/10.3390/en15176268.

[49] W. A. Raji, Y. Yerima, and P. T. Alufar, “Comparative Study on the Rates of Production of Biogas from Organic Substra
Energy and Power Engineering, vol. 10, no. 12, pp. 508–517, 2018, doi: https://doi.org/10.4236/epe.2018.1012032.
"Assessing the Viability of Biogas Production from Food Waste,"
[50] https://www.shell.com/what-we-do/technology-and-innovation/shell-techxplorer-digest/shell-techxplorer-digest-2020/_
ent/root/main/section/list_copy_copy_18695/list_item_copy_98181/links/item0.stream/1669888799100/189c06b2b80c
a1fb451c6d3faa4f396a7/assessing-the-viability-of-biogas-production-from-food-waste-al-wahaibi.pdf
R. Kaushal, S. Sandhu, and M. K. Soni, "Anaerobic co-digestion of food waste, algae, and cow dung for biogas y
[51] enhancement as a prospective approach for environmental sustainability," Sustain. Energy Technol. Assess., vol. 52, p
102236, 2022.
Y. Abbas, S. Yun, A. Mehmood, F. A. Shah, K. Wang, E. T. Eldin, and P. Bocchetta, "Co-digestion of cow manure
[52] food waste for biogas enhancement and nutrients revival in bio-circular economy," Chemosphere, vol. 311, p. 1370
2023.
Zhu, X.; Yellezuome, D.; Liu, R.; Wang, Z.; Liu, X. Effects of co-digestion of food waste, corn straw and chicken manu
[53] two-stage anaerobic digestion on trace element bioavailability and microbial community composition. Bioresour. Techn
346, 126625.
Speece, R.E.; Boonyakitsombut, S.; Kim, M.; Azbar, N.; Ursillo, P. Overview of Anaerobic Treatment: Thermophilic an
[54] Propionate Implications. Water Environ. Res. 2006, 78, 460–473

heng, Z.; Cai, Y.; Zhang, Y.; Zhao, Y.; Gao, Y.; Cui, Z.; Hu, Y.; Wang, X. The effects of C/N (10–25) on the relationship
[55] substrates, metabolites, and microorganisms in “inhibited steady-state” of anaerobic digestion. Water Res. 2021, 188, 1
A. Saleh, “Comparison among different models of biogas plants,” Jun. 26,
[56] https://www.researchgate.net/publication/279193347_Comparison_among_different_models_of_biogas_plants
[57] A. Mutungwazi, P. Mukumba, and G. Makaka, “Biogas digester types installed in South Africa: A review,” Renewable
Sustainable Energy Reviews, vol. 81, pp. 172–180, Jan. 2018, doi: https://doi.org/10.1016/j.rser.2017.07.051.
“Biogas Scrubbers - A Technical Review,” Industrial Instrumentation Products.
[58] https://allison.co.uk/products/biogas-scrubbers-a-technical-review/
A. Abdelouareth and M. Tamali, “Monitoring System Based Micro‐Controller for Biogas Digester,” Jul. 25, 2022.
[59] https://www.researchgate.net/publication/362640755_Monitoring_System_Based_Micro-Controller_for_Biogas_Diges
S. Li, D. Wang, L. He, and W. Wang, “CO2 bubbling pretreatment to remove the inhibition of lime disinfection wastewa
[60] swine manure anaerobic digestion system,” Journal of Cleaner Production, vol. 434, p. 140275, Dec. 2023, doi:
https://doi.org/10.1016/j.jclepro.2023.140275.
[61] Iliyass Ahlamine, A. Alla, and Noha El Khattabi, “Mathematical analysis of an anaerobic digestion model fo
production from solid waste,” Scientific Reports, vol. 14, no. 1, Oct. 2024, doi: https://doi.org/10.1038/s41598-024-774
A. G. Fiapshev, M. M. Khamokov, and O Kh Kilchukova, “Mathematical model of heat transfer in the reactor of
[62] plant,” Journal of Physics Conference Series, vol. 1679, no. 5, pp. 052074–052074, Nov. 202
https://doi.org/10.1088/1742-6596/1679/5/052074.

[63]

Tracking No.________________​ ​ ​ ​ ​ ​ ​ ​ ​ Page 37 of 39

​ ​
F. Lü, X. Xu, L. Shao, and P. He, “Importance of storage time in mesophilic anaerobic digestion of food waste,” J
Environmental Sciences, vol. 45, pp. 76–83, Jul. 2016, doi: https://doi.org/10.1016/j.jes.2015.11.019
[64] Karthikeyan OP, Visvanathan C. Bio-energy recovery from high-solid organic substrates by dry anaerobic bio-co
processes: a review. Rev Environ Sci Biotechnol 2013;12(3):257e84. https://doi.org/10.1007/s11157-012 9304-9.
[65] U. A. Ofon, U. U. Ndubuisi-Nnaji, S. E. Shaibu, O. K. Fatunla, and N.-A. O. Offiong, “Recycling anaerobic digestate
the co-digestion potential of agro-industrial residues: influence of different digestates as sources of microbial in
Environmental technology, pp. 1–12, Spring 2021, doi: https://doi.org/10.1080/09593330.2021.1952313.
[66] U. U. Ndubuisi-Nnaji, U. A. Ofon, and N.-A. O. Offiong, “Anaerobic co-digestion of spent coconut copra with cow
enhanced biogas production,” Waste Management & Research: The Journal for a Sustainable Circular Economy, vol.
pp. 594–600, Nov. 2020, doi: https://doi.org/10.1177/0734242x20975092.
[67] A. Tayyab et al., “Anaerobic co-digestion of catering food waste utilizing Parthenium hysterophorus as co-substrate f
production,” Biomass and Bioenergy, vol. 124, pp. 74–82, May 2019, doi: https://doi.org/10.1016/j.biombioe.2019.03.0
[68] G. W. Latimer, Ed., Official Methods of Analysis of AOAC INTERNATIONAL. Oxford University PressNew Yo
Available: https://academic.oup.com/aoac-publications/book/45491
[69] J. Ali, R. P. Singh, and V. Durgapal, “Biogas Production from Different Organic Biomass Materials by Anaerob
Fermentation,” American Journal of Biomass and Bioenergy, 2016, doi: https://doi.org/10.7726/ajbb.2016.1004.
[70] C. Zhang, G. Xiao, L. Peng, H. Su, and T. Tan, “The anaerobic co-digestion of food waste and cattle manure,” Bio
Technology, vol. 129, pp. 170–176, Feb. 2013, doi: https://doi.org/10.1016/j.biortech.2012.10.138.
[71] G. K. Kafle and L. Chen, “Comparison on batch anaerobic digestion of five different livestock manures and pred
biochemical methane potential (BMP) using different statistical models,” Waste Management, vol. 48, pp. 492–502, F
doi: https://doi.org/10.1016/j.wasman.2015.10.021.
[72] P. L. E. Bodelier and H. J. Laanbroek, “Nitrogen as a regulatory factor of methane oxidation in soils and sediments
Microbiology Ecology, vol. 47, no. 3, pp. 265–277, Mar. 2004, doi: https://doi.org/10.1016/s0168-6496(03)00304-0.
[73] Z. Z. Rasmeni, D. M. Madyira, and Antony. Matheri, “Comprehensive analysis of BSY as a biomass for potentia
resource recovery,” Energy Reports, vol. 8, pp. 804–810, Nov. 2022, doi: https://doi.org/10.1016/j.egyr.2022.10.272 .
[74] L. Jia, S. L. Xing, R. Tian, L. Y. Wang, and S. Li, “Electric Heating Biogas Digester Experimental Research and N
Simulation of Fluent,” Advanced Materials Research, vol. 724–725, pp. 236–240, Aug. 201
https://doi.org/10.4028/www.scientific.net/amr.724-725.236.
M. K. Jameel et al., “Biogas: Production, properties, applications, economic and challenges: A review,” Results in Chem
vol. 7, p. 101549, Jan. 2024, doi: https://doi.org/10.1016/j.rechem.2024.101549.
Rasi, S., et al. (2007). Biogas Composition and Upgrading. Biomass and Bioenergy.(PDF) Biogas composition and upg
biomethane
]B. Singh et al., “Enhancing Efficiency of Anaerobic Digestion by Optimization of Mixing Regimes Using Helica
Impeller,” Fermentation, vol. 7, no. 4, p. 251, Nov. 2021, doi: https://doi.org/10.3390/fermentation70402

XVII. Curriculum Vitae: See attached Form C

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