A REPORT OF THE INDUSTRIAL TRAINING PROGRAMME

UNDER THE STUDENT’S INDUSTRIAL WORK EXPERIENCE SCHEME

(SIWES)

AT

EL-FAD CONCEPTS LIMITED

LAGOS STATE.

BY

OYEDE SADEEEQ OLANREWAJU

MATRIC NO: 20192266

Department of Water Resources Management and Agro-meteorology

College of Environmental Resources Management
Federal University of Agriculture, Abeokuta.

OCTOBER, 2024.

i
 DECLARATION
I Oyede Sadeeq Olanrewaju, declare that this technical report was written by me. It
comprises of the summary of all the work done during my period of attachment at El-
Fad Concepts Limited Lagos State. I therefore submit the report work as partial
fulfillment of the requirements for the student industrial work experience scheme of the
Federal University of Agriculture Abeokuta.

_________________
Signature and Date

ii
 DEDICATIOIN
This report is dedicated to God Almighty for His steadfastness, faithfulness, protection,
guidance and love over me, my family and my loved ones

iii
 ABSTRACT
These report summaries the details of my Student Industrial Work Experience Scheme
(SIWES), which is an important training exercise put up by the Institution to help
students easily navigate through things taught in classes and how they work in the
industries and considering real life conditions and circumstances.
My program was done in ELFAD CONCEPT LTD, which is an engineering company
located in Lagos involved in Integrated Waste Treatment System(IWTS) for Sewage
solution. The basic goal of the company is to solve the problem of Evacuation of Sludge
by using an Anaerobic treatment plant which works on the concept of Anaerobic
Digestion thereby producing Bio-gas and Effluent rich in nutrients which after treatment
is safe for the environmental discharged and also for green environment.
A lot was gained there as I was able to supervise quite a number of projects on different
sites and also learn from them. The projects involved constructions of Anaerobic Bio-
digesters in which the digestion takes places which is designed to have a retention of
about 21 days for effective breakdown of fecal waste by microbes (methanogens) before
the effluent is being passed to a filtration bed which bio-cubes designed to properly treat
it and passed to a treatment tank to finally filter which they makes the effluent
environmentally friendly for Discharge.
I was made to know how to calculate the radius and also design for Volume of the bio-
digesters based on the amount of Usage. The project proved true as it has being done for
several residential houses and firms. It ensure people or Industries no longer have to
worry about evacuation for a long period of time (about 40 years) and prevents
environmental pollution.

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 ACKNOWLEDGMENT

I would like to express my sincere gratitude to God; my maker and provider, for helping
me through my SIWES program. I would also like to express my appreciation to the
staffs of ELFAD CONCEPT LTD most especially Engr Dele Fadipe and Engr Oladapo.
I was able to achieve all I did in the technical, theoretical and practical aspects through
their encouragement, lectures, tutelage, love and words of inspiration. The company
was always there to build up the confidence of everyone by regarding all staffs as
Engineers even though some of us know we aren’t yet. I am forever grateful. I am
immensely grateful to my Senior Colleagues for how much support then gave me and
how they even took me as there younger brother. Your labor is love is highly
appreciated. Also, I would like to thank my Parents for their moral and spiritual during
my SIWES program. They are simply the best. Finally, I want to express my gratitude
to the department of water resources management and agro-meteorology for giving me a
chance to have a feel of the practical knowledge associated with water Engineering. For
this, I am forever grateful.

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 Table of Contents
DECLARATION.......................................................................................................................................... ii
DEDICATIOIN ........................................................................................................................................... iii
ABSTRACT ................................................................................................................................................ iv
ACKNOWLEDGMENT .............................................................................................................................. v
Table of Contents ........................................................................................................................................ vi
Table of Figures.......................................................................................................................................... vii
CHAPTER ONE........................................................................................................................................... 1
1.0 History of student's Industrial Work Experience Scheme (SIWES .................................................... 1
1.2. Organization history .......................................................................................................................... 3
1.3. Company Structure ............................................................................................................................ 5
1.4 Roles and responsibilities ................................................................................................................... 6
CHAPTER TWO.......................................................................................................................................... 7
2.0 Role/Responsibility and daily Activities ............................................................................................ 7
2.1 Setting up of the Effluent treatment Cylinders ................................................................................. 11
2.3 Testing, Monitoring and Proper Handing Over ................................................................................ 12
CHAPTER THREE .................................................................................................................................... 14
3.0 Analysis and Evaluation ................................................................................................................... 14
3.1 Anaerobic Digestion ......................................................................................................................... 14
3.2 Anaerobic vs Aerobic Digestion ....................................................................................................... 16
3.3. Multi-Media Filters ......................................................................................................................... 18
3.4. Relevance of work done to academic discipline .............................................................................. 20
CHAPTER FOUR ...................................................................................................................................... 22
Conclusion and Recommendation .......................................................................................................... 22
4.0 Conclusion ........................................................................................................................................ 22
4.2 Limitations........................................................................................................................................ 22
4.3 Recommendation .............................................................................................................................. 23
References .................................................................................................................................................. 24

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 Table of Figures
Figure 1: An Overview of the Design Approach .............................................................. 8
Figure 2: The Construction Stage for the Bio-digesters ................................................. 10
Figure 3: A Baffle Reactor/ Filtration Bed under construction ...................................... 10
Figure 4: Effluent treatment tank made of Stainless steel .............................................. 11
Figure 5: Effluent treatment tank made of fibre ............................................................. 11
Figure 6: The chemical reaction that occur during anaerobic digestion......................... 15
Figure 7: Flow diagram of anaerobic digestin ................................................................ 15
Figure 8: A blower .......................................................................................................... 18
Figure 9: A diagram showing the components of a multi-media filter .......................... 20

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 CHAPTER ONE

1.0 History of student's Industrial Work Experience Scheme (SIWES

This section provides a brief history of the SIWES program as well as information
about the essence of SIWES; thereby re-emphasizing its importance to students of
tertiary institutions.
Universities and other tertiary institutions only succeed in providing students with
theoretical knowledge and little or no practical knowledge of their fields. Theoretical
knowledge alone is insufficient for any form of activity in the industries. In recognition
of the shortcomings and weaknesses in the formation of science, engineering and
technology graduates, particularly with respect to acquisition of relevant production
skills, the Industrial Training Fund (ITF) established the Students’ Industrial Work
Experience Scheme (SIWES) in 1973 to solve the problem of lack of adequate practical
skills preparatory for employment in industries by Nigerian graduates of tertiary
institutions. The scheme was to expose the students to industry based skills necessary
for smooth transition from classroom to the world of work. This was to afford the
students of tertiary institution the opportunity of being familiar and exposed to the
required experience in handling machinery and equipment which were not usually
available in educational institutions. Following the resumption of management of
SIWES by the ITF in 1984, the scheme has witnessed rapid expansion. Between 1985
and 1995, the numbers of institutions and students participating in SIWES rose to 141
and 57,433 respectively. Between 1995 and 2003, a total of 176 institutions and 535,210
students participated in the scheme. In 2008 alone, the number of institutions which
participated in the scheme rose to 204 while the number of students from these
institutions who participated in SIWES was 210,390. Presently, participation in the
scheme is limited to science, engineering and technology programs in Universities and
Polytechnics while in the Colleges of Education, NCE programs in Technical Education,
Agriculture, Business, Creative Arts and Design, Computer Studies and Home
Economics are eligible.

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1.1.1 Objectives of siwes
i. To Provide an avenue for students in institutions of higher learning to acquire
industrial skills and experience in their respective courses of study
ii. To Prepare students for industrial work situations that they are likely to meet
after graduation
iii. To Expose students to work methods and techniques in handling equipment and
machinery that may not be available in their institutions;
iv. To Make the transition from school to the world of work easier and enhance
students’ contacts for later job placements;
v. To provide students with the opportunities to apply their educational knowledge
in real work situations, thereby bridging the gap between theory and practice.
vi. To Enlist and strengthen employers’ involvement in the entire educational
process.

1.1. 2. Benefits of siwes to students

i. Opportunity for student to blend theoretical knowledge acquired in the
classroom with practical hands-on application of knowledge required to perform
work in industry.
ii. Exposure of student to the environment in which they will eventually work,
thereby enabling them to see how their future professions are organized in
practice.
iii. Minimization of the bewilderment experienced by students, particularly those
from a non-technological background, pursuing courses in science, engineering
and technology with regard to different equipment, processes, tools etc.
available in industry.
iv. Enabling science, engineering and technology students appreciate work methods
and gain experience in handling equipment and machinery which may not be
available in their institutions.
v. Preparing students to contribute to the productivity of their employers and
national development immediately after graduation.
vi. Provision of an enabling environment where students can develop and enhance
personal attributes such as critical thinking, creativity, initiative, resourcefulness,

2
 leadership, time management, presentation skills and interpersonal skills, among
others.

1.2. Organization history

ELFAD Concept Ltd is an indigenous Civil and environmental Engineering company

with operations in Nigeria and Ghana. It is located at shop D248, Ikota shopping
Complex, VGC, Lekki-Ajah Express way, Lagos The principal activity of the company
is to process and recycle organic waste both solid and Liquid on-site into re-usable by-
product. The treatment of sewage and biodegradable fractions of municipal solid waste,
Animal and Crop Farms is a response to the implementation of the Kyoto protocol (i.e.
reduction in emission of greenhouse gases).

1.2.1. The Company’s Vision/Mission

ELFAD Concept Ltd corporate mission is to provide a clean/safe environment by the
use of Integrated Waste Treatment System (IWTS) which eliminates sewage dumping
into our wetlands that poses threat to our ecosystem.

1.2.2. Activities of Elfad

ELFAD IWTS is an Anaerobic Digestion System (ADS) which is safer and cost
effective sewage and waste water solution that will permanently stop evacuation of
sludge as against the conventional septic tank system and other Sewage Treatment Plant
(STP).
Anaerobic digestion is a biological process whereby microbes break down organic
matter into useful end products such as
a) Inflammable gas as fuel;
b) Enriched Liquid organic effluent.
The Bio-gas provides a smokeless, high efficiency fuel for domestic purpose (cooking
and lighting), as well as heating and power generation. It acts as the pump in the reactor.
The IWTS is most suitable for highly Populated facilities and in conditions where there
is a high ground water table which can cause Water Ingress into the septic tanks
especially in Coastal and Niger delta environment. No land is lost due to the installation
of IWTS since the structure is underground hence the used space is recovered.

3
The IWTS consist of an inspection chamber, Dome Bio-digester, Expansion chamber
and filtration bed. The system operates via Gravity, capillary action and Filtration.
However, the effluent generated from the system has good nitrogen content, which can
be used as liquid fertilizer and can also be discharged into the environment.

DISTINCT FACTS/RESULTS FROM IWTS INSTALLATION

 IWTS is completely an Anaerobic Digestion system

 There will be no evacuation of sludge
 Bio-digesters require little or no supervision and requires less physical
contact with the sewage treatment plants hence it is the most suited for,
considering the COVID pandemic.
 Create clean and healthy alternative water source to service green areas
 Produces bio gas which could be utilized as energy for cooking
 Biodegradable medical waste can be introduced into the digester for
methane production
 Bio-gas is very safe as it cannot explode easily due to 35-40% CO2 in
the bio-gas mixture
 Super structure is not required to house IWTS
 No energy required to power the Bio-digester
 No land is lost as cars can park on the IWTS
 IWTS has a life span of about 40 years
 It comes in varying capacity
 IWTS is a hygienic sustainable sewage and waste water treatment
system.
IWTS has been tried and tested, proven effective and efficient in treating solid/organic
waste. The installations are in several places done by ELFAD Concepts Ltd which
includes private homes, banks, religious houses, Estates, Shopping malls, Hospitals,
Hotels, eatery and Tertiary Institution both in Nigeria and in Ghana.

4
1.3. Company Structure

ELFAD Concept is a private start-up company with about seven years of operation. The
organization has about thirty to thirty-five personnel playing different roles. It has the
managing director/CEO which is the real brain behind the project and involved in
decision making. It has a project manager who is in charge of the planning and
execution of projects from start to finish and also managing of all the engineers and
laborers. A team of site Engineers are also there who supervise the activities on each
sites they are on and use their knowledge and experiences to tackle several challenges
that comes up on site. The team of engineers which consists of people from several
engineering background like civil, mechanical, agricultural etc are also involved in
making designs, calculations and drawings for the IWTS. The company also has
artisans who render services such as the plumbers, electricians, Masons etc. Finally, it
has the laborers who are in charge of activities involving man power such as Excavation,
Mixing, transporting materials on sites etc.

MD/CEO

PROJECT MANAGER

SITE ENGINEERS

ARTISANS/TECHNICIANS

LABORERS/MAN POWER

5
1.4 Roles and responsibilities

During the six month period I was here, my roles as an Intern was majorly site
supervision. I was regarded and treated as a Site Engineer and also exposed to every
knowledge and information a site engineer most have. As the site engineer;

 I am responsible for Safety and site i.e. ensuring that the environment is in a safe
for the task to be performed and also for the workers that will be working.
Personal Protective equipment must be worn be the site engineer and also by the
workers working on site to prevent accidents or exposure to hazards.

 It is my duties to ensure all task was carried out according to the required
specifications and that the work is carried out according to details given.

 I get the target for the day and I then work around to achieve it with the team I
have and if it cannot be met, I give a reasonable explanation to why wasn’t.

 Taking the as built drawing for our installation positions on site for easy access
and location both for the company and the client, most especially during
maintenance.

 Stock taking of materials daily was also done to make sure work progresses as it
should and everyone has what is needed at the appropriate time.

 I also did lot of maintenance works on site where I go to inspect projects

already completed to be sure they are functioning properly and also to know
materials or tools that would be needed. I also check to see if there is any fault
and then call in the necessary persons to come fix it at the appropriate time.

6
 CHAPTER TWO

2.0 Role/Responsibility and daily Activities

This section provides well detailed information about the day to day activities
throughout the six month internship.
On the first day of resumption, I was made to understand what it is the company does
and also to know the management and staff. I was taking to two different sits; one
where the project was almost completed and the other were it was just commencing. I
was then placed to supervise a site where we are to execute a project of constructing a
100 cubic meter bio-digester for a Hotel under construction: I gained most of the
experiences on this site as I supervised the project from start to finish which the help of
my supervisor and other senior colleagues.

After this particular project, I was opportune to supervise 4 month projects from start to
finish giving me enough knowledge and experiences to explain in details what the
project entails. Most of the activities are routine in the long run, but different challenges
are met on site which have to be solved with different approach.
The details of all the activities carried out are given below;

Design stage
After meeting with the client and agreements have been reached to carry out the project,
the civil engineers in charge of design will do a design based on the estimation of
population in other to know what volume of Bio-digester to construct and what location
is best to place the entire system. A 10 cubic Bio-digester can serve a population of 50
active users which is about 5 residential apartments. Estimation for this is based on the
retention time of 21 days needed for the Bio-digester to breakdown the fecal wastes
coming in. During this stage, we check if we should centralize or decentralize the
system, based on the channels for the sewer lines. To centralize means to have a single
system in a position where it can serve the entire units it was designed for. This is
possible if the sewer lines have a location linking them together where we can place our
system without the fecal wastes having to travel long distance. The Decentralize means
to design for the smaller volumes but in different locations with the total volume when

7
added equal to the volume if it was centralized. This can be done for places like Estates
or locations with very large units like big farm lands.

Figure 1: An Overview of the Design Approach

After the location and type has been sorted out, we then do the calculation for the radius
of the Bio-digester. Since it’s a dome, it has the shape of a hemisphere so we get the
2
radius from the calculation of the volume of a hemisphere which is 𝜋𝑟 3 . For example,
3

by this calculation, a 10 cubic has a radius of 1.7m.

Lastly on this stage, we check the sewer lines of the buildings and see if we have
enough invert with our system and also we compare with the drainage to know if the
system can operate freely by gravity (Slope) or by the use of pumps and lift stations and
we then advice on the best to use considering cost and Maintenance.

Arrival of materials on site

After design has been completed, the required materials are transported to site where
they are to be used; the materials include cement, Sharp sand, plaster sand, granite,

8
water proof cement, Lime, pumping machines etc. Proper stock is taken and we ensure
that adequate provision is made before commencement of work.

Excavation
Since the entire system is to be done underground to allow for space recovery, we have
to do a deep Excavation of about 7ft, as we will be in need of that height for enough
inverts for our pipes and meeting the compound level. At this point, Safety is the first
requirement for operation. The Excavation can be done manually with the use of
laborers or by using an excavator with a skilled operator. As the Site Engineer, safety is
of high importance. Proper barricading of the working area first using caution tapes and
warning signs is done. Information as regards the drawings and building plans for the
site is also collected to know the things which are buried underground such as:
underground armored cables, pipes etc in order to avoid damage or hazards. After
Safety has been put in place, the Excavation can be carried out.

Construction of the Bio-digester Dome

After the Excavation is done, the commencement of construction of the Bio-digester

begins. The Bio-digester is designed to be run using anaerobic digestion which involves
completely sealing the Bio-digester to make it air tight. Bricks made out of burnt clay
are used in building the domes. This is due to its durability and ability to withstand high
temperature without losing its shape or strength. There is a bit of technicality in how the
Bio-digester should be constructed to give desired result and that’s why even though it
is Stone Masons that do the construction, an Engineer must be there to supervise the Job
and to give specific instructions as to how the construction should go. The Bio-digester
is to have an inflow from an inspection chamber (also called In-let chamber) and an out
flow into an Expansion chamber, the connections are done using pipes. The Expansion
pipe is to slope up to ensure that what comes out of the Bio-digester is liquid with just
suspended solid while the Inlet pipe slopes down at a level about Six-course work. As
the Engineer on Site, I am to make sure the sloping is properly done and also that the
required radius for the Bio-digester is used in order to build according to design. During

9
this stage I have to supervise every activity of the masons and Laborers and also do
quality test and check to ensure that the mix is done according to the required ratio.

Construction of the Inspection and Expansion Chambers

The base of the two is made to be above the base of the Bio-digester so that sludge can
drop into the dome and the effluent into the expansion is liquid. The inlet Chamber must
always be higher than the Expansion Chamber so that there won’t be high retention in
the In-let before a flow to the Expansion can occur. This is also critical and needs
serious supervision.

Construction of the filtration bed/ Bio-Cubes

This is also done by the Masons using block. We have a block construction of eight
chambers (cubes). The filtration Bed is constructed to treat the effluent coming from the

Figure 3: A Baffle Reactor/ Filtration Bed under construction

Figure 2: The Construction Stage for the Bio-digesters

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 Expansion chamber in other to remove odor, decolonize and treat the effluent to make it
safe to be discharged into the drainage or to be used for green areas as they are rich in
nutrients. Baffles are done to connect each chamber to another and direct the fluid flow,
with each chamber being loaded with several materials such as charcoal, activated
carbon, boulders, sharp sand, chlorine for filtration. There is an arrangement and
formula which must be followed to achieve the desired result. The filtration bed gives a
Pre-treatment to the effluent which can be further treated.

2.1 Setting up of the Effluent treatment Cylinders

The Effluent From the filtration bed is further treated in Filtration cylinders. The system
involves Multi-media filter, which involves the use of sand and anthracite in discrete
layers to yield very efficient filtration. They are also loaded in layers to make sure what
is being discharge is safe for the environment. This is the final treatment before
discharge and the materials also used to load it are also filtration materials such as
charcoal, activated carbon, Casite chemical. The Treatment cylinders have been aided
with Pre-treatment in the filtration bed and by post treatment (disinfection) steps to
remove pathogens and prevent fouling.

Figure 4: Effluent treatment tank made of Stainless

Figure 5: Effluent treatment tank made of fibre

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Running of the Effluent, In-fluent and Gas Pipes
After the construction and Building of the Bio-digesters and the Chambers, the gas line
can be run from the top of the dome to a safe area which can later be connected to the
kitchen for cooking. The pipes from the Sewer line are also connected to the inspection
chamber. If gravity is going to be used, there must be enough slopes to ensure smooth
flow of fecal waste without retention or it returning back, and as the site engineer I must
see to it that enough slopes is given. If pumps are to be used, lift stations are built in
which the wastes first flow inside, before the pumps then takes them into the inlet. The
pumps are connected to control panels by the electricians. The effluent pipe is the one
that connects the discharge either to the drainage or to the green areas for use.

Taking As-Built drawing

An as-built drawing is defined as a drawing created and submitted by a contractor after
completing a project. It helps show the exact position and location of every system and
rendering of the project. Although, this is the work of the Civil Engineers, but as the
engineer on site, I take measurements to pin-point the exact location of our system and
then send it to the civil Engineers for the as-built and building drawing which is also
sent to the client.

Back-filling, Carting away of Sand and Space recovery

After the As-built has been done, the entire area is back filled with sand again to cover
the spaces dug. Ramming is done to restore the area to how it was before and inspection
pipes are placed for easy access to the chambers. The remaining sand can be carted out
and the site cleaned out for use. The entire system is built not to fall more than 300mm
below the final compound level, for easy access during maintenance.

2.3 Testing, Monitoring and Proper Handing Over

After the design and construction stage, testing is left to be done when the clients begin
to use the system. Proper inspection is done to be sure all things are intact, and when the
system is in use, constant supervision is done daily for the site for a period of about one
week, and when all things are working fine, proper handing over of the running and

12
operation is done to the client. They are shown how to back wash the filtration cylinder
to avoid blockage, and how to control the pump panels and how often to flare the gas
when not in use at all to avoid build up. The gas is safe for burning as it completely
gives carbon (IV) oxide.

13
 CHAPTER THREE

3.0 Analysis and Evaluation

This section gives details about knowledge gained and experienced received during the
Internship.
Working with ELFAD gave insight and in depth knowledge about Anaerobic digestion
which will be discussed below;

3.1 Anaerobic Digestion

Anaerobic digestion is a natural biological process. The initials “AD” may refer to the
process of anaerobic digestion, or the built systems of anaerobic digesters. While there
are many kinds of digesters, the biology is basically the same for all. Anaerobic
digesters are built systems that deliberately harness the natural process. AD systems can
minimize odors and vector attraction, reduce pathogens, produce gas, produce liquid
and solid digestate, and reduce waste volumes. Anaerobically digesting organic carbon
involves naturally occurring bacteria. Digestion takes place when organic materials
decompose in an oxygen-free environment. Some digesters systems differentiate
between “wet” and “dry” digesters, or low-solid and high-solid systems, and sometimes
the process is called fermentation. The different language used to describe the same
processes reflect the varied historical uses and development of AD. During digestion,
various microbes use the organic matter such as animal manure, sewage sludge, wasted
food and other organics in the absence of oxygen. The process can be controlled and
enhanced through chemistry and engineering. The chemical reactions that occur in
stages during anaerobic digestion are hydrolysis, fermentation, also called acidogenesis
(the formation of soluble organic compounds and short-chain organic acids), and
methanogenesis (the bacterial conversion of organic acids into methane and carbon
dioxide) (Metcalf & Eddy, 2003).

14
 Figure 7: Flow diagram of anaerobic digestin
Figure 6: The chemical reaction that occur
during anaerobic digestion

In the methanogenesis step, acetic acid, carbon dioxide, and hydrogen are converted to
bio-gas by methanogens. Bio-gas consists mainly of methane and carbon dioxide and
can be used as a renewable energy fuel in a variety of applications.
AD systems are installed by stakeholders for many different purposes, such as a waste
treatment step, a means to reduce odors, a source of additional revenues, or a way to
improve public image. AD systems can impact several environmental sectors,
particularly methane control, production of renewable energy, and integrated waste
management.

Digesters produce bio-gas:

 Bio-gas is the gaseous product of AD.
 Bio-gas tends to be about 60% methane. Directly out of the digester it may
contain water, hydrogen sulfide, carbon dioxide, and other gases.
 Bio-gas can be: o burned to generate electricity, o burned to produce heat, o
compressed for vehicle fuel, o added to natural gas pipelines, or sometimes o a
combination of those uses.
 Bio-gas may require cleaning, drying, or other processing to meet a specific use.
 Some generators of the bio-gas may flare (waste) the gas.
 The amount of bio-gas production will vary based on feed stock, operation, and
process design.

15
 Digesters produce digestate:
 Digestate refers to any non-gas products coming from a digester, which in
some cases is separated into liquid and solid streams.
 The end uses of digestate are usually chosen based on its quality (e.g. nutrients,
degree of pathogen reduction), and local conditions including market demand.
 Digestate can be rich in nitrogen (particularly ammonia) and phosphorus.
Technologies are available to recover ammonia and phosphorus and produce
fertilizer products.
 Digestate uses include: o soil amendment, direct land application; o soil
amendment, processed, bagged, and sold; o animal bedding; and o alternative
daily cover for landfills.
 Some digestate needs further processing before it can be used for certain
purposes. This processing can include drying or composting.

3.2 Anaerobic vs Aerobic Digestion

There are some distinct advantages of aerobic digestion over the anaerobic digestion
process. The advantages include a reduced odor due to the non-production of hydrogen
sulfide or methane and better nutrient removal efficacy (facilitating direct discharge into
surface waters or disinfection). Despite this, aerobic treatment also has several
disadvantages. Oxygenation is an energy-intensive process severely increasing the
overall energy consumption, utility, and maintenance costs of the process. Solid waste
that microbes are not able to digest also often settle out as bio-solids which require
appropriate disposal which means additional costs.

Anaerobic treatment processes have many advantages over aerobic treatment processes.
The bio gas produced during an anaerobic treatment process can be used as a source of
renewable energy (natural gas/methane). This process also produces very low sludge
that is dewaterable and fully stabilized for disposal. Anaerobic treatment is less
expensive, simpler, and more flexible compared to aerobic treatment processes.

Both methods have clear advantages and disadvantages which is why a combination of
anaerobic and aerobic treatment processes are employed to achieve the most efficient
treatment of wastewater. Waste water going into an aerobic reactor will typically

16
undergo pre-treatment in an anaerobic reactor to fulfill wastewater standard discharge
requirements in an energy efficient and cost-effective manner. Also, to avoid increase in
bio-mass during discharge of effluent in Anaerobic digestion, there is need to introduce
oxygen to feed on nutrients using a Blower.

Table3.1. Table showing the difference between Aerobic and Anaerobic Treatment

PARAMETERS Aerobic Treatment Anaerobic Treatment

Application Low to medium strength Medium to high strength
wastewater (<1000 ppm) e.g wastewater (>4000 ppm) e.g
Municipal sewage, refinery Food and beverage industry
wastewater, etc. wastewater
Capital Investment Relatively high Relatively low with pay back
Energy Consumption Relatively high Relatively low

Foot-print Relatively large Relatively small and

compact
Net Sludge Yield Relatively high Relatively low
Post-treatment Typical direct discharge Required to fulfill
wastewater standard
discharge requirement

Example Technologies Activated Sludge Process Anaerobic Digesters (AD),

(ASP), Trickling Filter, and Continuous Stirred Tank
Rotating Biological Reactors (CSTR),
Contactor (RBC) Sequencing Batch Reactors
(SBR), Upflow Anaerobic
Sludge Blanket (UASB)
Reactors

17
 Figure 8: A blower

3.3. Multi-Media Filters

Multimedia filtration refers to a pressure filter vessel which utilizes three or more
different media as opposed to a “sand filter” that typically uses one grade of sand alone
as the filtration media. In a single media filter, during the “settling” cycle, the finest or
smallest media particles remain on top of the media bed while the larger, and heavier
particles, stratify proportional to their mass lower in the filter. This results in very
limited use of the media depth since virtually all filterable particles are trapped at the
very top of the filter bed or within 1-2 inches of the top where the filter media particles
have the least space between them. The filter run times are thus very short before the
filter “blinds” or develops so much head pressure that it must be backwashed to avoid
seriously impeding or stopping the flow.

Multi-media water filters typically utilize three layers of media for multimedia filtration:
anthracite, sand and garnet. These media are often chosen for use in multimedia filters
due to the distinct differences in their densities. Anthracite is the lightest filtration
media per unit volume, followed by sand, and then garnet.
The idea behind using media with differing masses is that during backwashing the
lightest media with the largest particles (anthracite) will naturally stratify at the top of
the filter, while the intermediate sized media (sand) will settle in the middle, and the
heaviest media with the smallest particles (garnet) will settle to the bottom.

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A typical multi-media filter setup contains three layers of filling. Those are anthracite,
sand and gravel.

 The anthracite traps the courser dirt particles to prevent the formation of a layer
cake on top of the filter bed.

 The smaller particles get trapped in the sand layer. With a low fluid velocity
particles will adhere to the sand with a cohesive bonding.

 The gravel allows the water to flow evenly to the mushroom diffusors and out of
the filter media.

This filter package allows the entire filter bed to function longer between back-wash. A
well operated filter removes particles down to 15-20 microns. With use of a coagulant
addition it can filter particles down to 5-10 microns.

Over time the pressure drop over the filter rises while the flow remains the same, due to
the adhered suspended solids. Eventually the filter media needs to be cleaned, a process
called back washing.

A backwash should be performed when the differential pressure exceeds 0,1-0,2 bar
over the differential pressure of a clean filter. A backwash should be performed at least
once a week to prevent clumping of the media. With a setup of valves the flow direction
over the filter reverses. At a velocity of 35m/h (depending on the type of media) the
filter bed expands. The particles detaches of the filter media grains due to the raised
velocity. The expanded gaps between the grains make sure it can exit the vessel. When
the velocity exceeds the maximum design specifications the filter bed expands to much
which will result in losing media out of the top during backwash.

As source for back washing the filter the filtered water of another (media) filter or raw
water which normally enters the filter at the top. With the use of raw water a small
amount of raw water entering the system downstream should be taken into account.

Another use of multi-media filters is the use as vessel for soluble materials. Some water
processes alter the pH value or other key values in an undesirable way. By filling the

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vessel with a slowly soluble granular material the key characteristics of the water can be
restored.

The Benefits of Multimedia Filtration over Conventional Sand Filters

Unlike traditional sand filters, multi-media water filters are composed of three filtration
media, ordered in decreasing porosity. Because of their multi-layer design, multi-media
water filters are able to trap and retain a far larger number of particles than traditional
sand filters before back-washing becomes necessary.
Trapping sediment and particulates throughout the entire depth of the filter bed, allows
multi-media water filters to operate for much longer periods of time than conventional
sand filters. The process of multimedia filtration produces high quality, filtered water at
much faster flow rates than traditional sand filtration.

3.4. Relevance of

work done to
Figure 9: A diagram showing the components of a multi-
media filter
academic discipline

The knowledge of chemical engineering gained within the four walls of the school
environment helped me in easily adapting in the work environment as I was now able to
get a clear insight on things taught in class and also able to quickly and easily relate

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 many practices and work done to what was taught in class or what had been done as
practical or laboratory experiments. Some of the courses offered in school were very
relevant in me understanding various processes. Below is an outline of some of the
course

Table 3.2. Table showing Courses and Area of Application

COURSE AREA OF APPLICATION

WMA 318 (Water quality assessment and water quality requirements,
pollution control)
WMA 307 (Water resources of Nigeria) Water supply and waste water
engineering, Anaerobic fermentation;
(aerobic, anaerobic and anoxic
conditions)
MCE 205 & MCE 305 (Fluid mechanics) Fluid flow
CVE 304 (Hydraulics) Open channel flow
CHM 305 (Environmental chemistry) Primary and secondary Waste water
treatment (aerobic anaerobic and anoxic
fermentation, baffle reactor, water
treatment plant).
WMA 314 (Surveying and Land measurement and site preparation
photogrammetry)
WMA 403(Principles of irrigation) Sprinkler installation

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 CHAPTER FOUR

Conclusion and Recommendation

4.0 Conclusion

The SIWES program proved reasonable and effective training for me and it was a
wonderful experience with lot of knowledge and insights gained.
My training Exercise covered exposed me to a lot of knowledge about sewage treatment
and Environmental Pollution and even fluid flow, which complemented my few years of
theoretical knowledge of hydrology. Not only that, I was also able to gain some
knowledge from other engineering discipline like Civil Engineering. With the laws been
made in states especially Lagos state, Sewage treatment Plants becomes a necessity
especially for commercial buildings and working with ELFAD Concept has helped to
broaden my view on the topic.
Also, the working environment helped me develop a good work ethics, team working
skills, multi-tasking and Supervision.
The objectives of the SIWES program were achieved as the gap between the classroom
study and Industry were bridged. SIWES is compulsory if students must graduate with
the best of information and qualifications the working environment requires.

4.2 Limitations

 Due to the company size and the specificity of what they do, there aren’t many
sectors or departments to work or function in unlike some companies/industries
having various departments a SIWES student can learn from and function
 Although different sites give different challenges and experiences, most of the
practices over time became routine.

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4.3 Recommendation

After the completion of the SIWES program, the following are recommended to aid
more involvement of students, school and the industry thus bringing a better result.

 School and Industry: the school and industry should keep a good relationship
so as to:
 Know the number of students needed by the organization and also their schedule
so as inform students in due time.
 Agree with the company on the training program that benefits school &
company interest.
 Organize orientation programs and invite organizations to inform students on
what is companies look out for.
 Industry and Students: The students should strictly adhere to the rules of the
organization and have a summary report of work done for each month. This
would help them focus in their learning.
 Student and School: There should be an awareness scheme where students
properly understand the reason for the industrial training and what the school
expects from them and which would be of compulsory attendance. This is
usually organized by the departmental organization however it should be made
compulsory and students should be encouraged to participate so as to capture the
essence.

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 References
 Bochmann, G., and Montogomery, L., (IEA Research cooperation), Pre-
treatment Technologies for Anaerobic Digestion:
http://www.iea.biogas.net/files/daten-
redaktion/download/publications/workshop/14 spring/Feed-stock Pre-treatment
Guenther Bochmann 04-04-2014.pdf
 http://www.swananys.org/pdf/AnaerobicDigestionofMunicipalsso.pdf
 Anaerobic Digestion Initiative Advisory Committee of Bc.
http://www.bcfarmbiogas.ca/opportunities/additional revenues

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