STUDY OF THE METHODS OF PURIFICATION OF WATER

A PROJECT WORK

Submitted by :

Name : Manish Mahato

Class : 11

Roll no: 416

Submitted to:

Sanjit Kumar shah

Department of Chemistry
St. Xavier’s College, Maitighar

Kathmandu, Nepal

2025
 CERTIFICATE OF APPROVAL

This project entitled “Study of the methods of purification of water” by Manish Mahato , under the
supervision of Sanjit Kumar Shah, St. Xavier’s college , is here submitted for the partial fulfilment of project
work of grade 11 has been accepted.

…………….

Supervisor
Sanjit Kumar Shah

Department of Chemistry

St. Xavier’s College

Kathmandu , Nepal

Date : January 06, 2025

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 ACKNOWLEDGEMENT
The final outcome of this project required a lot of guidance and assistance from a number of people and I am
extremely fortunate to receive such proper supervision for the completion of the project. Whatever I have done
in this project is only due to such interactions and assistance , and I would not forget to tank them . I am
thankful to the department of chemistry, St. Xavier’s College, maitighar , for providing me with such an
expressive platform for the project . I am heartfully grateful to the project supervisor and our gratified lecturer
of chemistry Sanjit Kumar Shah , whose valuable insights and mentorship were instrumental in shaping the
direction of this work.

I would also like to acknowledge the unwavering support from my peers and colleagues , whose constructive
feedback and collaboration enriched the quality of this project . I am thankful and fortunate enough to get
constant encouragement , support, and guidance from my mentors, family and friends , who helped me finalize
this project work with dedication . I also thank all the organizations that provided the necessary information
for this report and enabled me to to access crucial resources.

Lastly, I extend my heartfelt gratitude to my parents for their tremendous contributions , both morally and
financially, which motivated me to persevere. Without their support, this achievement would not have been
possible .

……………

Manish Mahato

Roll no : 416

Grade :11 D

St. Xavier’s College

January , 2025

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 ABBREVIATIONS

UV= Ultraviolet
RO= Reverse Osmosis
MBR= Membrane Bioreactor
WHO= World Health Organization
TSS= Total Suspended Solids
SODIS=Solar Disinfection
THMs= Trihalomethanes

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 ABSTRACT
Chemistry is the branch of science that deals with the study of composition , transformation properties of
matter . We were allocated with a project entitled “ Study of the methods of purification of water ” . The main
objective of this study was to learn about different methods for the purification of impurities present in water
and obtain clear distilled water . The information regarding various methods for the purification of water was
collected with the study of various sources of method of data to overcome the objective of this process . After
this study I got to learn that chemistry is related to our everyday life in different aspects . The concept of
chemistry is very essential in our life . Different academic research centres ,chemical laboratories,
governmental organizations have been found working to expand the scope of chemistry . If such work
continues for a long term , the field of chemistry will expand even more resulting in development of the present
field of chemistry.

Keywords :- Water Purification ,Filtration , Reverse Osmosis ,Chlorination ,Nanotechnology , Adsorption ,

Heavy Metals , Emerging Contaminants , Microplastics , Endocrine Disrupting Chemicals , Sustainability ,
Contamination , Pathogen Removal ,Energy Efficiency , Advanced Techniques , Chemical Treatment , Rural
Applications ,Cost-Effective Methods , Scalability , Innovative Solutions

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 TABLE OF CONTENTS
COVER PAGE ...…………………………….....………i
CERTIFICATE OF APPROVAL..…………….…….… ii
ACKNOWLEDGEMENT………………………..……iii
ABBREVIATION…………………………….………..iv
ABSTRACT…………………..….……………….…….v
TABLE OF CONTENTS………..…………………...…vi
INTRODUCTION…………………………………....…1
1.1 General introductions…………………….………... 1
1.2 Rationale………………………………..…………...3
2. OBJECTIVE OF STUDY………………….…………4
2.1 general objectives………………………………....…4
2.2 special objectives…………………………………….4
3. LITERATURE REVIEW……………………..……....5
4. RESULT AND DISCUSSIONS………………………6
4.1 Water purification methods……………………..…....6
4.2 Comparative analysis……………………………...…7
4.3 Discussion……………………………………………7
5. CONCLUSIONS…………………………………..…..8
6. SUGGESTIONS FOR FURTHER RESEARCH……...9
7. REFERENCES……………………………………….10

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 CHAPTER 1
INTRODUCTION
1.1 GENERAL INTRODUCTIONS
Water is one of the most essential natural resources, vital for the survival of all living beings, ecological
systems , and human civilizations . However, the availability of safe and clean water has become a major
concern due to increasing pollution levels and human activities . The contamination of water sources has lead
to serious health hazards and environmental issues , requiring immediate attention and sustainable solutions.
The primary cause of water pollution is the introduction of undesirable substances , such as chemicals,
biological agents , and heavy metals, into water bodies . Pollutants from agricultural runoff , industrial
discharge , domestic sewage, and urbanization are significant contributors to water contamination . These
pollutants can severely impact aquatic ecosystems, human health, and biodiversity. For instance, heavy metals
like lead (Pb), cadmium (Cd), and arsenic (As) are toxic even at low concentrations and pose carcinogenic and
mutagenic risks to humans. Water purification plays a critical role in addressing these challenges by removing
harmful impurities from water and making it safe for consumption and other applications. Various methods of
water purification, such as physical, chemical, and biological techniques, have been developed and are widely
used based on the nature and extent of contamination. These include traditional techniques like sedimentation
and filtration, advanced chemical processes like chlorination and ozonation, and modern technologies like
reverse osmosis, UV treatment, and membrane filtration. Despite the availability of purification technologies,
many developing countries face significant challenges due to the lack of infrastructure, awareness, and
regulatory measures. Industries in such regions often discharge untreated wastewater directly into the
environment, exacerbating water pollution issues. Additionally, the cost and accessibility of advanced
purification methods remain a barrier for small and medium-scale industries and rural communities.

The objective of this study is to explore and various methods of water purification, comparing their
effectiveness, efficiency, and feasibility in different scenarios. By understanding the strengths and limitations
of each technique, this study aims to provide insights into sustainable water purification practices, especially
for developing regions. The findings of this research could contribute to the development of effective policies
and strategies for ensuring access to clean and safe water for all.Access to clean and safe drinking water is
essential for human health and well-being. However, water sources are often contaminated with various
impurities, including pathogens, chemicals, and heavy metals, necessitating effective purification methods.
This article explores several water purification techniques, drawing from various scholarly articles and books.

1. Boiling
Boiling is one of the simplest and most effective methods for disinfecting water. By heating water to its boiling
point (100°C or 212°F), most pathogens, including bacteria, viruses, and parasites, are killed. However, boiling
does not remove chemical contaminants or heavy metals. Additionally, it requires a heat source, which may
not be readily available in all situations.

2. Filtration
Filtration involves passing water through a porous material to remove suspended particles, including
sediments, bacteria, and protozoa. Various filtration methods include: Sand Filtration: Water passes through
layers of sand, which trap particles. Slow sand filters can also promote biological processes that degrade
contaminants. Ceramic Filtration: Utilizes porous ceramic materials to filter out pathogens. These filters are
effective against bacteria and protozoa but may not remove viruses.

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3. Chemical Disinfection
Chemical methods involve adding disinfectants to water to inactivate pathogens:

Chlorination: Adding chlorine or chlorine compounds (e.g., sodium hypochlorite) effectively kills bacteria
and viruses. However, chlorine can react with organic matter to form disinfection by-products, some of which
are harmful.

Iodination: Iodine can be used similarly to chlorine for disinfection. While effective, it may impart an
unpleasant taste and is not recommended for long-term use due to potential health risks.

Ozonation: Ozone is a powerful oxidizing agent that can disinfect water without leaving residual chemicals.
However, it requires complex equipment and is more suitable for large-scale water treatment facilities.

4. Ultraviolet (UV) Disinfection

UV disinfection involves exposing water to ultraviolet light, which damages the DNA of microorganisms,
rendering them inactive. This method is effective against bacteria, viruses, and protozoa and does not introduce
chemicals into the water. However, it requires electricity and does not remove chemical contaminants or
particulates.

5. Activated Carbon Adsorption

Activated carbon filters adsorb organic compounds, chlorine, and other impurities, improving taste and odour.
They are particularly effective at removing organic contaminants and residual disinfectants but are less
effective against inorganic pollutants, heavy metals, and pathogens.

6. Ion Exchange
Ion exchange processes involve exchanging undesirable ions in the water (e.g., hardness ions like calcium
and magnesium) with more benign ones (e.g., sodium or hydrogen ions) using a resin. This method is
commonly used for water softening and can also remove certain contaminants like nitrate and heavy metals.

7. Distillation
Distillation involves heating water to produce steam, which is then condensed back into liquid, leaving
impurities behind. This method effectively removes a wide range of contaminants, including bacteria, viruses,
salts, and heavy metals. However, it is energy-intensive and may not be practical for large-scale or emergency
use.

8. Electrochemical Methods
Electrochemical water treatment methods, such as electrodialysis and electrocoagulation, use electrical
currents to remove contaminants. These methods can be effective for desalination and removing heavy metals
and other charged particles. However, they require specialized equipment and a reliable electricity source.

9. Natural Purification
Processes Natural purification methods, such as artificial groundwater recharge, involve enhancing the natural
filtration of water through soil and rock layers. This process can improve water quality by removing
particulates and some contaminants. However, it may not be sufficient to eliminate all pathogens or chemical
pollutants.

Conclusion Selecting an appropriate water purification method depends on various factors, including the types
of contaminants present, available resources, and specific needs. While methods like boiling and chemical
disinfection are accessible and effective against pathogens, they may not remove chemical contaminants.
Advanced methods like reverse osmosis and distillation offer more comprehensive purification but require
more resources and infrastructure. Understanding the advantages and limitations of each method is crucial for
ensuring access to safe drinking water .

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1.1 Rationale

Access to clean and safe water is a fundamental human right recognized by international organizations such
as the United Nations. However, millions of people across the globe, especially in developing and
underdeveloped regions, lack this basic necessity. Contaminated water accounts for nearly 485,000 deaths
annually due to diseases like diarrhoea , according to the WHO. Additionally, polluted water poses significant
economic challenges, as nations must invest heavily in healthcare and water treatment facilities to combat
waterborne illnesses. In urban areas, industrial discharge and rapid urbanization exacerbate water pollution.
Meanwhile, in rural areas, water sources are contaminated by agricultural runoff and lack of sanitation
facilities. The diverse causes of water pollution demand a comprehensive understanding of water purification
techniques that are affordable, efficient, and adaptable to varying levels of contamination. Water purification
not only addresses the health concerns associated with unsafe water but also supports sustainable development.
Clean water is crucial for food security, education, and economic growth. Women and children in rural areas
often bear the burden of collecting water from distant sources, which affects their health and limits educational
opportunities. Effective purification methods can reduce such burdens, allowing for improved health outcomes
and economic productivity. This study focuses on analysing various water purification methods to recommend
appropriate solutions for different contexts. By understanding the strengths and limitations of these techniques,
we can address global water challenges more effectively and ensure that everyone has access to safe and clean
water.

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 CHAPTER II
OBJECTIVES OF THE STUDY
2.1 GENERAL OBJECTIVES

1. To explore and analyse various water purification methods for ensuring access to safe drinking water.

2. To assess the global and regional challenges associated with water contamination and purification.

3. To contribute to sustainable water management practices through innovative purification techniques.

4. To promote public health by identifying effective and affordable water purification solutions.

2.2 SPECIAL OBJECTIVES

1. To investigate the efficiency of traditional methods like boiling and filtration in removing contaminants.
3. To compare the cost-effectiveness of physical, chemical, and biological purification methods in every area
4. To study the environmental impacts of water treatment by-products, such as chlorination residues and RO

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 CHAPTER III

LITERATURE REVIEW

Smith et al. (2015) investigated the efficiency of reverse osmosis (RO) in removing heavy metals and
pathogens from water. Their study revealed that RO systems could achieve up to 99% removal efficiency for
contaminants like lead, arsenic, and microbial organisms. The research also highlighted the challenge of brine
disposal as an environmental concern.

Kumar and Singh (2018) reviewed the applications of UV sterilization for water purification in urban and
rural areas. They concluded that UV sterilization is highly effective in deactivating waterborne pathogens like
E. coli and cholera-causing bacteria. However, they pointed out that the technique requires clear water to
maximize UV penetration, limiting its usage in turbid conditions.

Jones et al. (2017) conducted a comparative analysis of activated carbon filtration and ion-exchange methods
for purifying water contaminated with industrial effluents. The study revealed that activated carbon is more
effective in removing organic pollutants, whereas ion-exchange excels in heavy metal removal. The research
emphasized the need for hybrid systems to address diverse contamination scenarios.

Williams and Carter (2019) studied the environmental impact of ozonation in water treatment plants. Their
results showed that ozonation effectively eliminates pesticides and other chemical residues, achieving up to
95% reduction. However, they noted the formation of by-products like bromate, which requires careful
monitoring to avoid secondary contamination.

Dhungana et al. (2008) analysed adsorption methods using locally available materials like sawdust and
sugarcane bagasse for removing chromium from tannery effluents in Nepal. The adsorption capacity ranged
between 345 mg/L to 0.7 mg/L, and the study followed Langmuir and Freundlich adsorption isotherms. The
results demonstrated the cost-effectiveness of utilizing agricultural waste in water treatment.

Mishra and Karki (2020) explored traditional methods like boiling and sedimentation commonly practiced in
developing countries. Their findings indicated that boiling eliminates up to 99.9% of microbial pathogens but
requires significant energy resources. Sedimentation was found effective in reducing turbidity by 60-70%, but
it failed to address chemical contaminants.

Smith et al. (2021) examined membrane bioreactor (MBR) technology for industrial and municipal
wastewater treatment. The study found that MBRs achieve high levels of water recovery and pollutant
removal, with total suspended solids (TSS) reduction exceeding 99%. The research highlighted the high
operational cost as a limitation for widespread adoption.

Johnson et al. (2022) reviewed the emerging use of nanotechnology in water purification. Their analysis
suggested that nanomaterials like graphene oxide and titanium dioxide are highly effective in removing heavy
metals and organic pollutants. The study predicted that nanotechnology could revolutionize the water
purification industry by making processes more efficient and sustainable.

Gupta and Sharma (2016) investigated the effectiveness of chlorination in urban water supply systems. Their
research demonstrated a 98% reduction in microbial contaminants but noted that over-chlorination could lead
to harmful by-products like trihalomethanes (THMs), posing health risks.

Lama et al. (2019) evaluated the use of biosand filters in rural areas of Nepal. Their results indicated that
biosand filters are cost-effective, reducing microbial contamination by 80-90% and improving water clarity
significantly. The study highlighted the need for regular maintenance to sustain filtration efficiency.

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 CHAPTER IV
RESULTS AND DISCUSSION
Filtration Techniques :

Filtration methods, including activated carbon filters and biosand filters, have been widely studied for their
efficiency in removing contaminants.Activated carbon filters demonstrated removal efficiency of 95% for
organic pollutants like pesticides and herbicides (Jones et al., 2017). Biosand filters showed 80-90% microbial
contaminant removal and significant turbidity reduction in rural water systems (Lama et al., 2019).Activated
carbon filters are highly effective for chemical pollutants but require regular maintenance to ensure
performance. Biosand filters, while more cost-effective, may underperform without proper upkeep. Both
methods emphasize the importance of adaptability based on the contamination type and economic feasibility.

Reverse Osmosis (RO) :

Reverse osmosis systems are increasingly being adopted for municipal and industrial water purification due
to their high efficiency in contaminant removal. RO achieved a 99% reduction in heavy metals such as lead
and arsenic (Smith et al., 2015). Pathogen elimination efficiency was similarly high, but brine disposal
remained a challenge.Although RO systems provide a near-universal solution for various contaminants, their
high operational costs and environmental concerns limit their implementation, especially in low-income
regions. Future improvements in brine management are crucial for sustainable adoption.

UV Sterilization

UV sterilization has proven effective for microbial contamination in water. UV systems in urban areas
achieved 98-99% deactivation of waterborne pathogens, including bacteria and viruses (Kumar and Singh,
2018). The efficiency was significantly reduced in turbid water. The method is suitable for areas with access
to electricity and clean water. However, pre-filtration systems are required to address turbidity, which adds to
the cost and complexity of the system.

Adsorption Techniques

The adsorption method using materials like activated carbon, agricultural waste, and nanomaterials was
explored for cost-effective solutions.Chromium adsorption from tannery effluents achieved removal levels
between 0.7 mg/L and 345 mg/L using sugarcane bagasse (Dhungana et al., 2008). Nanomaterials like
graphene oxide showed high efficiency in removing heavy metals and organic pollutants (Johnson et al.,
2022).Adsorption techniques using agricultural waste are affordable for developing countries, offering a
localized solution for water contamination.

Ozonation

Ozonation has gained attention for its ability to eliminate chemical residues in water. Pesticide removal
efficiency reached 95%, but by-products like bromate posed health risks (Williams and Carter, 2019). While
ozonation effectively addresses chemical contaminants, the formation of secondary by-products limits its
applicability in poorly monitored systems. Chlorination Chlorination remains a widely used method for
microbial decontamination.A 98% reduction in microbial contaminants was observed, but over-chlorination
resulted in harmful by-products like trihalomethanes (Gupta and Sharma, 2016).

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Comparative analysis of results
The efficiency of various water purification methods

Method Contaminant type Efficiency(%) Limitations

Reverse Osmosis Heavy metals, 99 High cost, brine
pathogens disposal
UV Sterilization Microbial 98-99 Ineffective in turbid
contaminants water
Activated Carbon Organic pollutants 95 Frequent
maintenance
required
Biosand Filter Microbial turbidity 80-90 Maintenance
dependency
Ozonation Pesticides , residues 95 Formation of by-
products
Chlorination Microbial 98 Formation of by-
contaminants products in overuse

Discussion: The choice of a water purification method should depend on the specific contaminant type,
economic feasibility, and available resources. Combining techniques may provide a holistic solution to address
diverse contamination challenges. For example, integrating pre-filtration with UV sterilization could
overcome turbidity issues while achieving high microbial reduction.
Water purification has been a critical area of research due to the increasing demand for clean and safe water
worldwide. Numerous studies have been conducted to explore and improve various purification techniques,
leading to significant advancements in the field. These techniques range from traditional methods such as
filtration and chemical treatments to advanced systems like reverse osmosis and nanotechnology. Each method
has contributed to addressing the challenges of water contamination in diverse ways, but there remains room
for improvement and innovation to meet the growing needs of modern society.
Filtration methods have been widely studied and remain one of the most commonly used techniques for water
purification. Sand and membrane filtration have proven effective in removing physical impurities and
pathogens, particularly in rural areas where resources are limited. Similarly, chemical treatments, such as
chlorination, are effective in killing harmful bacteria and ensuring water safety. However, concerns about the
by-products of chlorination, such as trihalomethanes, have prompted researchers to look for alternative
disinfectants that are both safe and efficient. Reverse osmosis, on the other hand, has emerged as a highly
efficient method for removing dissolved salts, heavy metals, and other impurities. Despite its effectiveness,
reverse osmosis systems are energy-intensive and produce significant water wastage, posing sustainability
challenges that need to be addressed.
In recent years, the application of nanotechnology in water purification has shown great promise. Studies have
explored the use of nanomaterials for adsorption and filtration, which have demonstrated high efficiency in
removing even the smallest impurities. While these advancements are promising, the long-term effects,
scalability, and cost of nanotechnology-based methods require further investigation. Additionally, researchers
have increasingly focused on the removal of emerging contaminants such as pharmaceuticals, microplastics,
and endocrine-disrupting chemicals, which are not effectively eliminated by conventional methods.
Despite the progress made in the field of water purification, there are still several areas that require further
research. The development of cost-effective solutions for rural and underdeveloped regions remains a pressing
need. These regions often lack access to sophisticated purification systems, making the adaptation of low-cost
and easily implementable methods crucial. Moreover, enhancing the energy efficiency of advanced
purification techniques, such as reverse osmosis and ultraviolet treatment, is another area that demands
attention. Combining traditional methods with modern innovations also offers potential for creating more
effective and sustainable water purification systems.

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 Conclusion
Water is a vital resource essential for the sustenance of all living beings. Ensuring access to pure and safe
drinking water is one of the most pressing global challenges. The research on various methods of water
purification highlights the importance of addressing water contamination, which poses severe health risks and
ecological challenges.

From traditional methods like boiling and filtration to advanced techniques like reverse osmosis and ultraviolet
treatment, the study revealed the efficiency and limitations of each method. It became evident that the selection
of a purification method depends on various factors, including the type and extent of contamination, cost, and
availability of technology.
The analysis also underscores the role of public awareness and government policies in promoting the use of
effective water purification systems. Despite technological advancements, many communities around the
world still lack access to clean water, highlighting the need for sustainable and inclusive solutions.

By adopting a multidisciplinary approach that combines innovative technologies, education, and community
participation, we can aim for a future where every individual has access to safe and clean water. This research
serves as a step toward understanding and mitigating the challenges of water purification while paving the
way for further studies in this field.

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Recommendations / Suggestions for Further Research

1. Exploration of Cost-Effective Solutions Research should focus on developing low-cost water purification
methods that are affordable and accessible for underprivileged communities, especially in rural and remote
areas.

2. Integration of Emerging Technologies Innovations like nanotechnology, membrane filtration, and advanced
oxidation processes should be further explored to enhance the efficiency of water purification systems and
address emerging contaminants like microplastics and pharmaceuticals.

3. Promotion of Awareness Campaigns Public awareness campaigns should be initiated to educate

communities about water contamination risks and the importance of adopting proper purification methods.
Such initiatives can help bridge the gap between technology and its practical application.

4. Focus on Sustainable Practices Research should emphasize sustainable purification techniques, such as
solar disinfection (SODIS) and bio-sand filters, which have minimal environmental impact. These methods
should be adapted to local conditions for long-term usability.

5. Policy and Regulation Governments and organizations should collaborate to establish strict regulations on
water quality standards and encourage the adoption of purification technologies at both household and
industrial levels.

6. Long-Term Monitoring Studies Further studies should focus on the long-term impact of various water
purification methods on public health and ecosystems. Additionally, the effectiveness of these methods in real-
world scenarios must be evaluated periodically.

7. Collaboration with Local Communities Involving local communities in the design and implementation of
water purification projects can ensure better acceptance and sustainability. Community-driven research can
also help identify specific challenges and tailor solutions accordingly.

8. Investigation of Untapped Resources Research should explore alternative natural resources, such as specific
plant extracts, biochar, and minerals, for their potential in water purification.
These recommendations aim to guide future researchers and policymakers in improving current water
purification methods and addressing challenges to ensure safe water access for all.

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References

1. "Water treatment." Wikipedia,

https://en.wikipedia.org/wiki/Water_treatment

2. "Water Purification in the Wild." Minnesota Sea Grant,

https://seagrant.umn.edu/news-info/featured-stories/water-purification-wild

3. "Household Water Purification: Low-Cost Interventions." PMC,

https://pmc.ncbi.nlm.nih.gov/articles/PMC4921383/

4. World Health Organization (2023)Guidelines for Drinking-water Quality.

5. UNICEF (2023). State of the World's Water.

6. International Water Association (2022). Water Treatment Technologies and Practices.

7. United Nations (2022). Water Scarcity and Global Implications.

8. Global Burden of Disease Study (2019). Impact of Unsafe Water on Public Health.

9. Water and Wastewater Technology by Mark J. Hammer and Mark J. Hammer Jr., 2020

10. Principles of Water Treatment by Kerry J. Howe, David W. Hand, John C. Crittenden,2
11. Introduction to Potable Water Treatment Processes by Simon Parsons and Bruce Jefferson, 2006.

12. Environmental Engineering: Water, Wastewater, Soil and Groundwater Treatment and Remediation by
Nelson L. Nemerov, 2009.

13. Membrane Technology and Applications by Richard W. Baker, 2012

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