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Wastewater Pollution

Turning a Critical Problem into Opportunity

Sewage pipe with sunset in the background.

Wastewater is a major threat to nature and human health.

Without adequate treatment, wastewater can contribute to habitat loss and extinction. TNC is actively addressing this through innovative science, strategic communications and policy interventions.

A Scary Status Quo

Every day 80% of the world’s wastewater enters our environment completely untreated, jeopardizing nature and public health, with far-reaching consequences for climate resilience, aquatic biodiversity and food and water security and access. Wastewater introduces a toxic cocktail of contaminants that threaten our food and water security as well as marine species. 

What's in wastewater? Pathogens, pharmaceuticals, microplastics, heavy metals, endocrine disruptors and more.

Our existing wastewater treatment systems allow us to “flush it and forget it,” avoiding the complex reality of wastewater pollution. Ignoring this critical issue leads to dangerous consequences, some of which we are already seeing like closed beaches, collapsed fisheries and algal blooms that suffocate aquatic life. 

Wastewater Pollution is Everywhere

An open palm dipping fingertips in green sludge producing green fingers.

TNC’s Solution

TNC scientists and conservation practitioners are addressing the dangerous impacts of wastewater pollution with a whole-system approach.

In addition to TNC’s on-the-ground projects across the globe, our dedicated wastewater pollution program is working across the Pacific to coordinate partners, develop foundational science and find solutions that work.

  • Comms & Policy
  • Science & Research
  • Green Solutions

Climate Impacts

Eyes on wastewater.

Wastewater can often be a hidden threat. Click through this slideshow to see what's just below the surface.

2 divers inspect the effects of Delray Beach sewage outfall on the coral reef in Florida.

Ocean Sewage: 2 divers inspect the effects of Delray Beach sewage outfall on the coral reef in Florida. © Steve Spring/Palm Beach County Reef Rescue

Coastal Pollution: Riverine discharges to coastal areas. Studies have linked wastewater pollution to seagrass die-offs, harmful algal blooms and weakened reefs. © Malik Naumann/Flickr

Sewage Contaminated Water: Ignoring wastewater pollution can have dangerous consequences, some of which we are already seeing like closed beaches, collapsed fisheries and algal blooms. © Brian Auer

Wastewater Pollution: Wastewater introduces a toxic cocktail of contaminants that threaten our food and water security as well as marine species. © Tom Fisk

Marin County Sewage: Richardson Bay in Marin County, CA is one of the sites in the Bat Area that has experienced sewage spills. © KQED Quest/Flickr

Strategic Communications & Policy

For too many, wastewater pollution flies under the radar or is simply categorized as someone else’s problem. Cultural taboo, combined with misconceptions about the capacity of oceans and other water systems to absorb wastewater, limits our ability to find and implement solutions. So much of the answer hinges on raising awareness.

It's time the world understood the critical threat wastewater pollution poses to humans and the natural systems we depend on.

That’s why TNC is building awareness and education through partnerships to reach broader audiences and drive campaigns that reduce stigma around wastewater and inspire action. We’re working across sectors to produce and share research, tools, and best practices while highlighting the intersections between wastewater pollution, public health and the environment. 


  • TNC’s collaboration with the Reef Resilience Network provides wastewater pollution training, tools, and learning resources for coral reef practitioners. 
  • Our work alongside partners at the Ocean Sewage Alliance  to build a first-of-its-kind knowledge hub and resource library on marine wastewater pollution. 


If the world is to meet the UN's Sustainable Development Goals , we'll need significant policy reform. Many of the world’s wastewater policies and regulations are inadequate and based on outdated science that neither accounts for modern-day stressors nor recognizes the economic opportunity of wastewater resource recovery. TNC is exploring avenues for policy interventions to reduce and mitigate wastewater pollution for human health and environmental protection.

Shoreline along Long Island Sound in Connecticut.

Coastal Long Island, NY

Nitrogen pollution has had a devastating effect on Long Island’s water quality for decades, causing harmful algal blooms and threatening bivalves, like oysters and mussels, as well as seagrass and salt marsh habitats. TNC’s Long Island team, in collaboration with a myriad of government and private sector partners, knew their restoration work wouldn't be successful without dealing directly with the pollution's source: the island’s half-million septic systems and cesspools. Find out how they worked with policymakers and partners at the federal and local level to secure funding and policy reforms necessary to do just that — from homeowner assistance for upgrading septic systems to building clean water infrastructure across the state that mitigates the effects of wastewater pollution. As of 2024, this coalition continues to work on a major ballot valued at $6B over the next 35 years, to create a county wide water quality restoration act to substantially increase the local funding for clean septic change outs and strategic sewer expansion. This fund would be the key to unlocking federal and state infrastructure funding.

Research & Monitoring

The global scientific community is increasingly recognizing the profound impact that wastewater pollution has on aquatic ecosystems. TNC scientists and field staff are on the front lines monitoring water quality to inform wastewater pollution mitigation and management strategies. 

Studies have linked wastewater pollution to seagrass die-offs, harmful algal bloom events and weakened reefs that can destabilize entire ecosystems. Even coastal wetlands, which naturally absorb nutrients, can become oversaturated when exposed to wastewater pollution over time, making these systems more vulnerable to extreme weather events exacerbated by climate change. 

"Contaminants of emerging concern” (CECs) in wastewater, like  PFAS , pharmaceuticals, and other novel chemicals not only threaten drinking water and human health but are also contaminating coastal waters and fisheries. 


TNC’s plan for ocean recovery is expansive. We have a goal of conserving 10 billion acres of ocean worldwide. In order to achieve this goal, we must ensure that wastewater does not threaten the health and quality of the marine waters we protect.

Nature-based Solutions

Nature-based solutions are interventions that harness the power of Earth’s natural features and functions. These can look like dunes and wetlands that insulate coasts from storm surge, or native forest restoration in the face of megafires.

TNC and partners are employing nature-based solutions to address wastewater. One of the most promising solutions our team is studying is constructed wetlands . These are engineered systems designed for wastewater treatment that use natural biological technologies that incorporate wetland vegetation, soils, and microorganisms to remove contaminants.

This can be a cost-effective and sustainable option, and TNC is implementing solutions like these across the globe. From the Dominican Republic to India, our team is demonstrating that constructed wetlands can be an effective, nature-based mitigation strategy to improve water quality and restore wildlife habitat. 

An aerial city view of Lake Sembakkam.

Constructed Wetlands in Lake Sembakkam

In Chennai, the largest city in India’s southern state of Tamil Nadu, a 100-acre wetland has been restored to protect Lake Sembakkam. Rapid urbanization, including increases in wastewater and stormwater pollution, has caused the lake to degrade over time. This is one of many critical natural wetlands that serve as a lifeline for the city’s people and wildlife—including several rare and threatened species of migratory birds. TNC’s India program helped design and restore these wetlands to support biodiversity and to improve habitat, water quality, groundwater storage and recharge, and recreation landscape. Read more about how these constructed wetlands work and why TNC is expanding the project to the broader system of Chennai’s marshland.

Climate change and wastewater pollution are two inextricably linked crises. 

It’s estimated that wastewater treatment plants account for at least 3% of all greenhouse gas emissions, in addition to supplemental emissions from direct discharge into waterways. Beyond the treatment process, wastewater pollution is also a significant threat to some of the key ecosystems we rely on to store carbon, including mangrove forests and seagrass beds. To complicate the matter, the effects of climate change—from sea level rise to the increase in extreme weather events—are overburdening wastewater treatment systems that are already stressed and outdated. 

But if we change the status quo, addressing wastewater pollution can provide multiple avenues for tackling climate change. It starts with implementing treatment options that better protect carbon-storing ecosystems. These options are even more effective when coupled with investment in innovative practices that divert waste into valuable resources, such as reclaimed water, biofuel and fertilizer.

In Florida, TNC and partners have helped pave the way for more widespread reuse of wastewater, helping craft legislation that bans the use of ocean outfalls that discharge treated wastewater directly to the coastal zone within Southeast Florida by 2025, instead encouraging reuse. 

Make Transformative Change Possible.

We depend on nature, and nature depends on those of us who care enough to stand up for it.

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Wastewater Treatment and Reuse: a Review of its Applications and Health Implications

  • Open access
  • Published: 10 May 2021
  • Volume 232 , article number  208 , ( 2021 )

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  • Kavindra Kumar Kesari   ORCID: orcid.org/0000-0003-3622-9555 1   na1 ,
  • Ramendra Soni 2   na1 ,
  • Qazi Mohammad Sajid Jamal 3 ,
  • Pooja Tripathi 4 ,
  • Jonathan A. Lal 2 ,
  • Niraj Kumar Jha 5 ,
  • Mohammed Haris Siddiqui 6 ,
  • Pradeep Kumar 7 ,
  • Vijay Tripathi 2 &
  • Janne Ruokolainen 1  

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Water scarcity is one of the major problems in the world and millions of people have no access to freshwater. Untreated wastewater is widely used for agriculture in many countries. This is one of the world-leading serious environmental and public health concerns. Instead of using untreated wastewater, treated wastewater has been found more applicable and ecofriendly option. Moreover, environmental toxicity due to solid waste exposures is also one of the leading health concerns. Therefore, intending to combat the problems associated with the use of untreated wastewater, we propose in this review a multidisciplinary approach to handle wastewater as a potential resource for use in agriculture. We propose a model showing the efficient methods for wastewater treatment and the utilization of solid wastes in fertilizers. The study also points out the associated health concern for farmers, who are working in wastewater-irrigated fields along with the harmful effects of untreated wastewater. The consumption of crop irrigated by wastewater has leading health implications also discussed in this review paper. This review further reveals that our current understanding of the wastewater treatment and use in agriculture with addressing advancements in treatment methods has great future possibilities.

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1 Introduction

Rapidly depleting and elevating the level of freshwater demand, though wastewater reclamation or reuse is one of the most important necessities of the current scenario. Total water consumption worldwide for agriculture accounts 92% (Clemmens et al., 2008 ; Hoekstra & Mekonnen, 2012 ; Tanji & Kielen, 2002 ). Out of which about 70% of freshwater is used for irrigation (WRI, 2020 ), which comes from the rivers and underground water sources (Pedrero et al., 2010 ). The statistics shows serious concern for the countries facing water crisis. Shen et al. ( 2014 ) reported that 40% of the global population is situated in heavy water–stressed basins, which represents the water crisis for irrigation. Therefore, wastewater reuse in agriculture is an ideal resource to replace freshwater use in agriculture (Contreras et al., 2017 ). Treated wastewater is generally applied for non-potable purposes, like agriculture, land, irrigation, groundwater recharge, golf course irrigation, vehicle washing, toilet flushes, firefighting, and building construction activities. It can also be used for cooling purposes in thermal power plants (Katsoyiannis et al., 2017 ; Mohsen, 2004 ; Smith, 1995 ; Yang et al., 2017 ). At global level, treated wastewater irrigation supports agricultural yield and the livelihoods of millions of smallholder farmers (Sato et al., 2013 ). Global reuse of treated wastewater for agricultural purposes shows wide variability ranging from 1.5 to 6.6% (Sato et al., 2013 ; Ungureanu et al., 2018 ). More than 10% of the global population consumes agriculture-based products, which are cultivated by wastewater irrigation (WHO, 2006 ). Treated wastewater reuse has experienced very rapid growth and the volumes have been increased ~10 to 29% per year in Europe, the USA, China, and up to 41% in Australia (Aziz & Farissi, 2014 ). China stands out as the leading country in Asia for the reuse of wastewater with an estimated 1.3 M ha area including Vietnam, India, and Pakistan (Zhang & Shen, 2017 ). Presently, it has been estimated that, only 37.6% of the urban wastewater in India is getting treated (Singh et al., 2019 ). By utilizing 90% of reclaimed water, Israel is the largest user of treated wastewater for agriculture land irrigation (Angelakis & Snyder, 2015 ). The detail information related to the utilization of freshwater and treated wastewater is compiled in Table 1 .

Many low-income countries in Africa, Asia, and Latin America use untreated wastewater as a source of irrigation (Jiménez & Asano, 2008 ). On the other hand, middle-income countries, such as Tunisia, Jordan, and Saudi Arabia, use treated wastewater for irrigation (Al-Nakshabandi et al., 1997 ; Balkhair, 2016a ; Balkhair, 2016b ; Qadir et al., 2010 ; Sato et al., 2013 ).

Domestic water and treated wastewater contains various type of nutrients such as phosphorus, nitrogen, potassium, and sulfur, but the major amount of nitrogen and phosphorous available in wastewater can be easily accumulated by the plants, that’s why it is widely used for the irrigation (Drechsel et al., 2010 ; Duncan, 2009 ; Poustie et al., 2020 ; Sengupta et al., 2015 ). The rich availability of nutrients in reclaimed wastewater reduces the use of fertilizers, increases crop productivity, improves soil fertility, and at the same time, it may also decrease the cost of crop production (Chen et al., 2013 a; Jeong et al., 2016 ). The data of high nutritional values in treated wastewater is shown in Fig. 1 .

figure 1

Nutrient concentrations (mg/L) of freshwater/wastewater (Yadav et al., 2002 )

Wastewater reuse for crop irrigation showed several health concerns (Ungureanu et al., 2020 ). Irrigation with the industrial wastewater either directly or mixing with domestic water showed higher risk (Chen et al., 2013). Risk factors are higher due to heavy metal and pathogens contamination because heavy metals are non-biodegradable and have a long biological half-life (Chaoua et al., 2019 ; WHO, 2006 ). It contains several toxic elements, i.e., Cu, Cr, Mn, Fe, Pb, Zn, and Ni (Mahfooz et al., 2020 ). These heavy metals accumulate in topsoil (at a depth of 20 cm) and sourcing through plant roots; they enter the human and animal body through leafy vegetables consumption and inhalation of contaminated soils (Mahmood et al., 2014 ). Therefore, health risk assessment of such wastewater irrigation is important especially in adults (Mehmood et al., 2019 ; Njuguna et al., 2019 ; Xiao et al., 2017 ). For this, an advanced wastewater treatment method should be applied before release of wastewater in the river, agriculture land, and soils. Therefore, this review also proposed an advance wastewater treatment model, which has been tasted partially at laboratory scale by Kesari and Behari ( 2008 ), Kesari et al. ( 2011a , b ), and Kumar et al. ( 2010 ).

For a decade, reuse of wastewater has also become one of the global health concerns linking to public health and the environment (Dang et al., 2019 ; Narain et al., 2020 ). The World Health Organization (WHO) drafted guidelines in 1973 to protect the public health by facilitating the conditions for the use of wastewater and excreta in agriculture and aquaculture (WHO, 1973 ). Later in 2005, the initial guidelines were drafted in the absence of epidemiological studies with minimal risk approach (Carr, 2005 ). Although, Adegoke et al. ( 2018 ) reviewed the epidemiological shreds of evidence and health risks associated with reuse of wastewater for irrigation. Wastewater or graywater reuse has adverse health risks associated with microbial hazards (i.e., infectious pathogens) and chemicals or pharmaceuticals exposures (Adegoke et al., 2016 ; Adegoke et al., 2017 ; Busgang et al., 2018 ; Marcussen et al., 2007 ; Panthi et al., 2019 ). Researchers have reported that the exposure to wastewater may cause infectious (helminth infection) diseases, which are linked to anemia and impaired physical and cognitive development (Amoah et al., 2018 ; Bos et al., 2010 ; Pham-Duc et al., 2014 ; WHO, 2006 ).

Owing to an increasing population and a growing imbalance in the demand and supply of water, the use of wastewater has been expected to increase in the coming years (World Bank, 2010 ). The use of treated wastewater in developed nations follows strict rules and regulations. However, the direct use of untreated wastewater without any sound regulatory policies is evident in developing nations, which leads to serious environmental and public health concerns (Dickin et al., 2016 ). Because of these issues, we present in this review, a brief discussion on the risk associated with the untreated wastewater exposures and advanced methods for its treatment, reuse possibilities of the treated wastewater in agriculture.

2 Environmental Toxicity of Untreated Wastewater

Treated wastewater carries larger applicability such as irrigation, groundwater recharge, toilet flushing, and firefighting. Municipal wastewater treatment plants (WWTPs) are the major collection point for the different toxic elements, pathogenic microorganisms, and heavy metals. It collects wastewater from divergent sources like household sewage, industrial, clinical or hospital wastewater, and urban runoff (Soni et al., 2020 ). Alghobar et al. ( 2014 ) reported that grass and crops irrigated with sewage and treated wastewater are rich in heavy metals in comparison with groundwater (GW) irrigation. Although, heavy metals classified as toxic elements and listed as cadmium, lead, mercury, copper, and iron. An exceeding dose or exposures of these heavy metals could be hazardous for health (Duan et al., 2017 ) and ecological risks (Tytła, 2019 ). The major sources of these heavy metals come from drinking water. This might be due to the release of wastewater into river or through soil contamination reaches to ground water. Table 2 presenting the permissible limits of heavy metals presented in drinking water and its impact on human health after an exceeding the amount in drinking water, along with the route of exposure of heavy metals to human body.

Direct release in river or reuse of wastewater for irrigation purposes may create short-term implications like heavy metal and microbial contamination and pathogenic interaction in soil and crops. It has also long-term influence like soil salinity, which grows with regular use of untreated wastewater (Smith, 1995 ). Improper use of wastewater for irrigation makes it unsafe and environment threatening. Irrigation with several different types of wastewater, i.e., industrial effluents, municipal and agricultural wastewaters, and sewage liquid sludge transfers the heavy metals to the soil, which leads to accumulation in crops due to improper practices. This has been identified as a significant route of heavy metals into aquatic resources (Agoro et al., 2020 ). Hussain et al. ( 2019 ) investigated the concentration of heavy metals (except for Cd) was higher in the soil irrigated with treated wastewater (large-scale sewage treatment plant) than the normal ground water, also reported by Khaskhoussy et al. ( 2015 ).

In other words, irrigation with wastewater mitigates the quality of crops and enhances health risks. Excess amount of copper causes anemia, liver and kidney damage, vomiting, headache, and nausea in children (Bent & Bohm, 1995 ; Madsen et al., 1990 ; Salem et al., 2000 ). A higher concentration of arsenic may lead to bone and kidney cancer (Jarup, 2003 ) and results in osteopenia or osteoporosis (Puzas et al., 2004 ). Cadmium gives rise to musculoskeletal diseases (Fukushima et al., 1970 ), whereas mercury directly affects the nervous system (Azevedo et al., 2014 ).

3 Spread of Antibiotic Resistance

Currently, antibiotics are highly used for human disease treatment; however, uses in poultries, animal husbandries, biochemical industries, and agriculture are common practices these days. Extensive use and/or misuse of antibiotics have given rise to multi-resistant bacteria, which carry multiple resistance genes (Icgen & Yilmaz, 2014 ; Lv et al., 2015 ; Tripathi & Tripathi, 2017 ; Xu et al., 2017 ). These multidrug-resistant bacteria discharged through the sewage network and get collected into the wastewater treatment plants. Therefore, it can be inferred that the WWTPs serve as the hotspot of antibiotic-resistant bacteria (ARB) and antibiotic resistance genes (ARGs). Though, these antibiotic-resistant bacteria can be disseminated to the different bacterial species through the mobile genetic elements and horizontal gene transfer (Gupta et al., 2018 ). Previous studies indicated that certain pathogens might survive in wastewater, even during and after the treatment processes, including methicillin-resistant Staphylococcus aureus (MRSA) and vancomycin-resistant enterococci (VRE) (Börjesson et al., 2009 ; Caplin et al., 2008 ). The use of treated wastewater in irrigation provides favorable conditions for the growth and persistence of total coliforms and fecal coliforms (Akponikpe et al., 2011 ; Sacks & Bernstein, 2011 ). Furthermore, few studies have also reported the presence of various bacterial pathogens, such as Clostridium , Salmonella , Streptococci , Viruses, Protozoa, and Helminths in crops irrigated with treated wastewater (Carey et al., 2004 ; Mañas et al., 2009 ; Samie et al., 2009 ). Goldstein ( 2013 ) investigated the survival of ARB in secondary treated wastewater and proved that it causes serious health risks to the individuals, who are exposed to reclaimed water. The U.S. Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) have already declared the ARBs as the imminent hazard to human health. According to the list published by WHO, regarding the development of new antimicrobial agents, the ESKAPE ( Enterococcus faecium , S. aureus , Klebsiella pneumoniae , Acinetobacter baumannii , Pseudomonas aeruginosa , and Enterobacter species) pathogens were designated to be “priority status” as their occurrence in the food chain is considered as the potential and major threat for the human health (Tacconelli et al., 2018 ).

These ESKAPE pathogens have acquired the multi drug resistance mechanisms against oxazolidinones, lipopeptides, macrolides, fluoroquinolones, tetracyclines, β-lactams, β-lactam–β-lactamase inhibitor combinations, and even those antibiotics that are considered as the last line of defense, including carbapenems and glycopeptides (Giddins et al., 2017 ; Herc et al., 2017 ; Iguchi et al., 2016 ; Naylor et al., 2018 ; Zaman et al., 2017 ), by the means of genetic mutation and mobile genetic elements. These cluster of ESKAPE pathogens are mainly responsible for lethal nosocomial infections (Founou et al., 2017 ; Santajit & Indrawattana, 2016 ).

Due to the wide application of antibiotics in animal husbandry and inefficient capability of wastewater treatment plants, the multidrug-resistant bacteria such as tetracyclines, sulfonamides, β-lactam, aminoglycoside, colistin, and vancomycin in major are disseminated in the receiving water bodies, which ultimately results in the accumulation of ARGs in the irrigated crops (He et al., 2020 ).

4 Toxic Contaminations in Wastewater Impacting Human Health

The release of untreated wastewater into the river may pose serious health implications (König et al., 2017 ; Odigie, 2014 ; Westcot, 1997 ). It has been already discussed about the household and municipal sewage which contains a major amount of organic materials and pathogenic microorganisms and these infectious microorganisms are capable of spreading various diseases like typhoid, dysentery, diarrhea, vomiting, and malabsorption (Jia & Zhang, 2020 ; Numberger et al., 2019 ; Soni et al., 2020 ). Additionally, pharmaceutical industries also play a key role in the regulation and discharge of biologically toxic agents. The untreated wastewater also contains a group of contaminants, which are toxic to humans. These toxic contaminations have been classified into two major groups: (i) chemical contamination and (ii) microbial contamination.

4.1 Chemical Contamination

Mostly, various types of chemical compounds released from industries, tanneries, workshops, irrigated lands, and household wastewaters are responsible for several diseases. These contaminants can be organic materials, hydrocarbons, volatile compounds, pesticides, and heavy metals. Exposure to such contaminants may cause infectious diseases like chronic dermatoses and skin cancer, lung infection, and eye irritation. Most of them are non-biodegradable and intractable. Therefore, they can persist in the water bodies for a very long period and could be easily accumulated in our food chain system. Several pharmaceutical personal care products (PPCPs) and surfactants are available that may contain toxic compounds like nonylphenol, estrone, estradiol, and ethinylestradiol. These compounds are endocrine-disrupting chemicals (Bolong et al., 2009 ), and the existence of these compounds in the human body even in the trace amounts can be highly hazardous. Also, the occurrence of perfluorinated compounds (PFCs) in wastewater, which is toxic in nature, has been significantly reported worldwide (Templeton et al., 2009 ). Furthermore, PFCs cause severe health menaces like pre-eclampsia, birth defects, reduced human fertility (Webster, 2010 ), immunotoxicity (Dewitt et al., 2012 ), neurotoxicity (Lee & Viberg, 2013 ), and carcinogenesis (Bonefeld-Jorgensen et al., 2011 ).

4.2 Microbial Contamination

Researchers have reported serious health risks associated with the microbial contaminants in untreated wastewater. The diverse group of microorganisms causes severe health implications like campylobacteriosis, diarrhea, encephalitis, typhoid, giardiasis, hepatitis A, poliomyelitis, salmonellosis, and gastroenteritis (ISDH, 2009 ; Okoh et al., 2010 ). Few bacterial species like P. aeruginosa , Salmonella typhimurium , Vibrio cholerae , G. intestinales , Legionella spp., E. coli , Shigella sonnei have been reported for the spreading of waterborne diseases, and acute illness in human being (Craun et al., 2006 ; Craun et al., 2010 ). These aforementioned microorganisms may release in the environment from municipal sewage water network, animal husbandries, or hospitals and enter the food chain via public water supply systems.

5 Wastewater Impact on Agriculture

The agriculture sector is well known for the largest user of water, accounting for nearly 70% of global water usage (Winpenny et al., 2010 ). The fact that an estimated 20 million hectares worldwide are irrigated with wastewater suggests a major source for irrigation (Ecosse, 2001 ). However, maximum wastewater that is used for irrigation is untreated (Jiménez & Asano, 2008 ; Scott et al., 2004 ). Mostly in developing countries, partially treated or untreated wastewater is used for irrigation purpose (Scott et al., 2009 ). Untreated wastewater often contains a large range of chemical contaminants from waste sites, chemical wastes from industrial discharges, heavy metals, fertilizers, textile, leather, paper, sewage waste, food processing waste, and pesticides. World Health Organization (WHO) has warned significant health implications due to the direct use of wastewater for irrigation purposes (WHO, 2006 ). These contaminants pose health risks to communities (farmers, agricultural workers, their families, and the consumers of wastewater-irrigated crops) living in the proximity of wastewater sources and areas irrigated with untreated wastewater (Qadir et al., 2010 ). Wastewater also contains a wide variety of organic compounds. Some of them are toxic or cancer-causing and have harmful effects on an embryo (Jarup, 2003 ; Shakir et al., 2016 ). The pathway of untreated wastewater used in irrigation and associated health effects are shown in Fig. 2 .

figure 2

Exposure pathway representing serious health concerns from wastewater-irrigated crops

Alternatively, in developing countries, due to the limited availability of treatment facilities, untreated wastewater is discharged into the existing waterbodies (Qadir et al., 2010 ). The direct use of wastewater in agriculture or irrigation obstructs the growth of natural plants and grasses, which in turn causes the loss of biodiversity. Shuval et al. ( 1985 ) reported one of the earliest evidences connecting to agricultural wastewater reuse with the occurrence of diseases. Application of untreated wastewater in irrigation increases soil salinity, land sealing followed by sodium accumulation, which results in soil erosion. Increased soil salinity and sodium accumulation deteriorates the soil and decreases the soil permeability, which inhibits the nutrients intake of crops from the soil. These causes have been considered the long-term impact of wastewater reuse in agriculture (Halliwell et al., 2001 ). Moreover, wastewater contaminated soils are a major source of intestinal parasites (helminths—nematodes and tapeworms) that are transmitted through the fecal–oral route (Toze, 1997 ). Already known, the helminth infections are linked to blood deficiency and behavioral or cognitive development (Bos et al., 2010 ). One of the major sources of helminth infections around the world is the use of raw or partially treated sewage effluent and sludge for the irrigation of food crops (WHO, 1989 ). Wastewater-irrigated crops contain heavy metal contamination, which originates from mining, foundries, and metal-based industries (Fazeli et al., 1998 ). Exposure to heavy metals including arsenic, cadmium, lead, and mercury in wastewater-irrigated crops is a cause for various health problems. For example, the consumption of high amounts of cadmium causes osteoporosis in humans (Dickin et al., 2016 ). The uptake of heavy metals by the rice crop irrigated with untreated effluent from a paper mill has been reported to cause serious health concerns (Fazeli et al., 1998 ). Irrigating rice paddies with highly contaminated water containing heavy metals leads to the outbreak of Itai-itai disease in Japan (Jarup, 2003 ).

Owing to these widespread health risks, the WHO published the third edition of its guidelines for the safe use of wastewater in irrigating crops (WHO, 2006 ) and made recommendations for threshold contaminant levels in wastewater. The quality of wastewater for agricultural reuse have been classified based on the availability of nutrients, trace elements, microorganisms, and chemicals contamination levels. The level of contamination differs widely depending on the type of source, household sewage, pharmaceutical, chemical, paper, or textile industries effluents. The standard measures of water quality for irrigation are internationally reported (CCREM, 1987 ; FAO, 1985 ; FEPA, 1991 ; US EPA, 2004 , 2012 ; WHO, 2006 ), where the recommended levels of trace elements, metals, COD, BOD, nitrogen, and phosphorus are set at certain limits. Researchers reviewed the status of wastewater reuse for agriculture, based on its standards and guidelines for water quality (Angelakis et al., 1999 ; Brissaud, 2008 ; Kalavrouziotis et al., 2015 ). Based on these recommendations and guidelines, it is evident that greater awareness is required for the treatment of wastewater safely.

6 Wastewater Treatment Techniques

6.1 primary treatment.

This initial step is designed to remove gross, suspended and floating solids from raw wastewater. It includes screening to trap solid objects and sedimentation by gravity to remove suspended solids. This physical solid/liquid separation is a mechanical process, although chemicals can be used sometimes to accelerate the sedimentation process. This phase of the treatment reduces the BOD of the incoming wastewater by 20–30% and the total suspended solids by nearly 50–60%.

6.2 Secondary (Biological) Treatment

This stage helps eliminate the dissolved organic matter that escapes primary treatment. Microbes consume the organic matter as food, and converting it to carbondioxide, water, and energy for their own growth. Additional settling to remove more of the suspended solids then follows the biological process. Nearly 85% of the suspended solids and biological oxygen demand (BOD) can be removed with secondary treatment. This process also removes carbonaceous pollutants that settle down in the secondary settling tank, thus separating the biological sludge from the clear water. This sludge can be fed as a co-substrate with other wastes in a biogas plant to obtain biogas, a mixture of CH 4 and CO 2 . It generates heat and electricity for further energy distribution. The leftover, clear water is then processed for nitrification or denitrification for the removal of carbon and nitrogen. Furthermore, the water is passed through a sedimentation basin for treatment with chlorine. At this stage, the water may still contain several types of microbial, chemical, and metal contaminations. Therefore, to make the water reusable, e.g., for irrigation, it further needs to pass through filtration and then into a disinfection tank. Here, sodium hypochlorite is used to disinfect the wastewater. After this process, the treated water is considered safe to use for irrigation purposes. Solid wastes generated during primary and secondary treatment processes are processed further in the gravity-thickening tank under a continuous supply of air. The solid waste is then passed into a centrifuge dewatering tank and finally to a lime stabilization tank. Treated solid waste is obtained at this stage and it can be processed further for several uses such as landfilling, fertilizers and as a building.

Other than the activated sludge process of wastewater treatment, there are several other methods developed and being used in full-scale reactors such as ponds (aerobic, anaerobic, facultative, and maturation), trickling filters, anaerobic treatments like up-flow anaerobic sludge blanket (UASB) reactors, artificial wetlands, microbial fuel cells, and methanogenic reactors.

UASB reactors are being applied for wastewater treatment from a very long period. Behling et al. ( 1996 ) examined the performance of the UASB reactor without any external heat supply. In their study, the COD loading rate was maintained at 1.21 kg COD/m 3 /day, after 200 days of trial. They achieved an average of 85% of COD removal. Von-Sperling and Chernicharo ( 2005 ) presented a combined model consisted of an Up-flow Anaerobic Sludge Blanket-Activated Sludge reactor (UASB–AS system), using the low strength domestic wastewater with a BOD 5 amounting to 340 mg/l. Outcomes of their experiment have shown a 60% reduction in sludge construction and a 40% reduction in aeration energy consumption. In another experiment, Rizvi et al. ( 2015 ) seeded UASB reactor with cow manure dung to treat domestic wastewater; they observed 81%, 75%, and 76% reduction in COD, TSS, and total sulfate removal, respectively, in their results.

6.3 Tertiary or Advanced Treatment Processes

The tertiary treatment process is employed when specific constituents, substances, or contaminants cannot be completely removed after the secondary treatment process. The tertiary treatment processes, therefore, ensure that nearly 99% of all impurities are removed from wastewater. To make the treated water safe for drinking purposes, water is treated individually or in combination with advanced methods like the US (ultrasonication), UV (ultraviolet light treatment), and O 3 (exposure to ozone). This process helps to remove bacteria and heavy metal contaminations remaining in the treated water. For the purpose, the secondarily treated water is first made to undergo ultrasonication and it is subsequently exposed to UV light and passed through an ozone chamber for the complete removal of contaminations. The possible mechanisms by which cells are rendered inviable during the US include free-radical attack and physical disruption of cell membranes (Phull et al., 1997 ; Scherba et al., 1991 ). The combined treatment of US + UV + O 3 produces free radicals, which are attached to cell membranes of the biological contaminants. Once the cell membrane is sheared, chemical oxidants can enter the cell and attack internal structures. Thus, the US alone or in combination facilitates the deagglomeration of microorganisms and increases the efficiency of other chemical disinfectants (Hua & Thompson, 2000 ; Kesari et al., 2011a , b ; Petrier et al., 1992 ; Phull et al., 1997 ; Scherba et al., 1991 ). A combined treatment method was also considered by Pesoutova et al. ( 2011 ) and reported a very effective method for textile wastewater treatment. The effectiveness of ultrasound application as a pre-treatment step in combination with ultraviolet rays (Blume & Neis, 2004 ; Naddeo et al., 2009 ), or also compared it with various other combinations of both ultrasound and UV radiation with TiO 2 photocatalysis (Paleologou et al., 2007 ), and ozone (Jyoti & Pandit, 2004 ) to optimize wastewater disinfection process.

An important aspect of our wastewater treatment model (Fig. 3 ) is that at each step of the treatment process, we recommend the measurement of the quality of treated water. After ensuring that the proper purification standards are met, the treated water can be made available for irrigation, drinking or other domestic uses.

figure 3

A wastewater treatment schematic highlighting the various methods that result in a progressively improved quality of the wastewater from the source to the intended use of the treated wastewater for irrigation purposes

6.4 Nanotechnology as Tertiary Treatment of Wastewater Converting Drinking Water Alike

Considering the emerging trends of nanotechnology, nanofillers can be used as a viable method for the tertiary treatment of wastewater. Due to the very small pore size, 1–5-nm nanofillers may eliminate the organic–inorganic pollutants, heavy metals, as well as pathogenic microorganisms and pharmaceutically active compounds (PhACs) (Mohammad et al., 2015 ; Vergili, 2013 ). Over the recent years, nanofillers have been largely accepted in the textile industry for the treatment of pulp bleaching pharmaceutical industry, dairy industry, microbial elimination, and removal of heavy metals from wastewater (Abdel-Fatah, 2018 ). Srivastava et al. ( 2004 ) synthesized very efficient and reusable water filters from carbon nanotubes, which exhibited effective elimination of bacterial pathogens ( E. coli and S. aureus ), and Poliovirus sabin-1 from wastewater.

Nanofiltration requires lower operating pressure and lesser energy consumption in comparison of RO and higher rejection of organic compounds compared to UF. Therefore, it can be applied as the tertiary treatment of wastewater (Abdel-Fatah, 2018 ). Apart from nanofilters, there are various kinds of nanoparticles like metal nanoparticles, metal oxide nanoparticles, carbon nanotubes, graphene nanosheets, and polymer-based nanosorbents, which may play a different role in wastewater treatment based on their properties. Kocabas et al. ( 2012 ) analyzed the potential of different metal oxide nanoparticles and observed that nanopowders of TiO 2 , FeO 3 , ZnO 2 , and NiO can exhibit the exceeding amount of removal of arsenate from wastewater. Cadmium contamination in wastewater, which poses a serious health risk, can be overcome by using ZnO nanoparticles (Kumar & Chawla, 2014 ). Latterly, Vélez et al. ( 2016 ) investigated that the 70% removal of mercury from wastewater through iron oxide nanoparticles successfully performed. Sheet et al. ( 2014 ) used graphite oxide nanoparticles for the removal of nickel from wastewater. An exceeding amount of copper causes liver cirrhosis, anemia, liver, and kidney damage, which can be removed by carbon nanotubes, pyromellitic acid dianhydride (PMDA) and phenyl aminomethyl trimethoxysilane (PAMTMS) (Liu et al., 2010 ).

Nanomaterials are efficiently being used for microbial purification from wastewater. Carbon nanotubes (CNTs) are broadly applied for the treatment of wastewater contaminated with E. coli , Salmonella , and a wide range of microorganisms (Akasaka & Watari, 2009 ). In addition, silver nanoparticles reveal very effective results against the microorganisms present in wastewater. Hence, it is extensively being used for microbial elimination from wastewater (Inoue et al., 2002 ). Moreover, CNTs exhibit high binding affinity to bacterial cells and possess magnetic properties (Pan & Xing, 2008 ). Melanta ( 2008 ) confirmed and recommended the applicability of CNTs for the removal of E. coli contamination from wastewater. Mostafaii et al. ( 2017 ) suggested that the ZnO nanoparticles could be the potential antibacterial agent for the removal of total coliform bacteria from municipal wastewater. Apart from the previously mentioned, applicability of the nanotechnology, the related drawbacks and challenges cannot be neglected. Most of the nanoengineered techniques are currently either in research scale or pilot scale performing well (Gehrke et al., 2015 ). Nevertheless, as discussed above, nanotechnology and nanomaterials exhibit exceptional properties for the removal of contaminants and purification of water. Therefore, it can be adapted as the prominent solution for the wastewater treatment (Zekić et al., 2018 ) and further use for drinking purposes.

6.5 Wastewater Treatment by Using Plant Species

Some of the naturally growing plants can be a potential source for wastewater treatment as they remove pollutants and contaminants by utilizing them as a nutrient source (Zimmels et al., 2004 ). Application of plant species in wastewater treatment may be cost-effective, energy-saving, and provides ease of operation. At the same time, it can be used as in situ, where the wastewater is being produced (Vogelmann et al., 2016 ). Nizam et al. ( 2020 ) analyzed the phytoremediation efficiency of five plant species ( Centella asiatica , Ipomoea aquatica , Salvinia molesta , Eichhornia crassipes , and Pistia stratiotes ) and achieved the drastic decrease in the amount of three pollutants viz. total suspended solids (TSS), ammoniacal nitrogen (NH 3 -N), and phosphate levels . All the five species found to be efficient removal of the level of 63.9-98% of NH 3 -N, TSS, and phosphate. Coleman et al. ( 2001 ) examined the physiological effects of domestic wastewater treatment by three common Appalachian plant species: common rush or soft rush ( Juncus effuses L.), gray club-rush ( Scirpus Validus L.), and broadleaf cattail or bulrush ( Typha latifolia L.). They observed in their experiments about 70% of reduction in total suspended solids (TSS) and biochemical oxygen demand (BOD), 50% to 60% of reduction in nitrogen, ammonia, and phosphate levels, and a significant reduction in feacal coliform populations. Whereas, Zamora et al. ( 2019 ) found the removal efficiency of chemical oxygen demand (COD), total solids suspended (TSS), nitrogen as ammonium (N-NH 4 ) and nitrate (N-NO 3 ), and phosphate (P-PO 4 ) up to 20–60% higher using the three ornamental species of plants viz. Canna indica , Cyperus papyrus , and Hedychium coronarium . The list of various plant species applied for the wastewater treatment is shown in Table 3 .

6.6 Wastewater Treatment by Using Microorganisms

There is a diverse group of bacteria like Pseudomonas fluorescens , Pseudomonas putida , and different Bacillus strains, which are capable to use in biological wastewater systems. These bacteria work in the cluster forms as a floc, biofilm, or granule during the wastewater treatment. Furthermore, after the recognition of bacterial exopolysaccharides (EPS) as an efficient adsorption material, it may be applied in a revolutionary manner for the heavy metal elimination (Gupta & Diwan, 2017 ). There are few examples of EPS, which are commercially available, i.e., alginate ( P. aeruginosa , Azotobacter vinelandii ), gellan (Sphingomonas paucimobilis ), hyaluronan ( . aeruginosa , Pasteurella multocida , Streptococci attenuated strains ), xanthan (Xanthomonas campestris ), and galactopol ( Pseudomonas oleovorans ) (Freitas et al., 2009 ; Freitas, Alves, & Reis, 2011a ; Freitas, Alves, Torres, et al., 2011b ). Similarly, Hesnawi et al. ( 2014 ) experimented biodegradation of municipal wastewater using local and commercial bacteria (Sludge Hammer), where they achieved a significant decrease in synthetic wastewater, i.e., 70%, 54%, 52%, 42% for the Sludge Hammer, B. subtilis , B. laterosponus , and P. aeruginosa , respectively. Therefore, based on the above studies, it can be concluded that bioaugmentation of wastewater treatment reactor with selective and mixed strains can ameliorate the treatment. During recent years, microalgae have attracted the attention of researchers as an alternative system, due to their applicability in wastewater treatment. Algae are the unicellular or multicellular photosynthetic microorganism that grows on water surfaces, salt water, or moist soil. They utilize the exceeding amount of nutrients like nitrogen, phosphorus, and carbon for their growth and metabolism process through their anaerobic system. This property of algae also inhibits eutrophication; that is to avoid over-deposit of nutrients in water bodies. During the nutrient digestion process, algae produce oxygen that is constructive for the heterotrophic aerobic bacteria, which may further be utilized to degrade the organic and inorganic pollutants. Kim et al. ( 2014 ) observed a total decrease in the levels of COD (86%), total nitrogen (93%), and total phosphorus (83%) after using algae in the municipal wastewater consortium. Nmaya et al. ( 2017 ) reported the heavy metal removal efficiency of microalga Scenedesmus sp. from contaminated river water in the Melaka River, Malaysia. They observed the effective removal of Zn (97-99%) on the 3 rd and 7 th day of the experiment. The categorized list of microorganisms used for wastewater treatment is presented in Table 4 .

7 The Computational Approach in Wastewater Treatment

7.1 bioinformatics and genome sequencing.

A computational approach is accessible in wastewater treatment. Several tools and techniques are in use such as, sequencing platforms (Hall, 2007 ; Marsh, 2007 ), metagenome sequencing strategies (Schloss & Handelsman, 2005 ; Schmeisser et al., 2007 ; Tringe et al., 2005 ), bioinformatics tools and techniques (Chen & Pachter, 2005 ; Foerstner et al., 2006 ; Raes et al., 2007 ), and the genome analysis of complex microbial communities (Fig. 4 ). Most of the biological database contains microorganisms and taxonomical information. Thus, these can provide extensive details and supports for further utilization in wastewater treatment–related research and development (Siezen & Galardini, 2008 ). Balcom et al. ( 2016 ) explored that the microbial population residing in the plant roots immersed in the wastewater of an ecological WWTP and showed the evidence of the capacity for micro-pollutant biodegradation using whole metagenome sequencing (WMS). Similarly, Kumar et al. ( 2016 ) revealed that bioremediation of highly polluted wastewater from textile dyes by two novel strains were found to highly decolorize Joyfix Red. They were identified as Lysinibacillus sphaericus (KF032717) and Aeromonas hydrophila (KF032718) through 16S rDNA analysis. More recently, Leddy et al. ( 2018 ) reported that research scientists are making strides to advance the safety and application of potable water reuse with metagenomics for water quality analysis. The application of the bio-computational approach has also been implemented in the advancements of wastewater treatment and disease detection.

figure 4

A schematic showing the overall conceptual framework on which depicting the computational approach in wastewater treatment

7.2 Computational Fluid Dynamics in Wastewater Treatment

In recent years, computational fluid dynamics (CFD), a broadly used method, has been applied to biological wastewater treatment. It has exposed the inner flow state that is the hydraulic condition of a biological reactor (Peng et al., 2014 ). CFD is the application of powerful predictive modeling and simulation tools. It may calculate the multiple interactions between all the water quality and process design parameters. CFD modeling tools have already been widely used in other industries, but their application in the water industry is quite recent. CFD modeling has great applications in water and wastewater treatment, where it mechanically works by using hydrodynamic and mass transfer performance of single or two-phase flow reactors (Do-Quang et al., 1998 ). The level of CFD’s capability varies between different process units. It has a high frequency of application in the areas of final sedimentation, activated sludge basin modeling, disinfection, and greater needs in primary sedimentation and anaerobic digestion (Samstag et al., 2016 ). Now, researchers are enhancing the CFD modeling with a developed 3D model of the anoxic zone to evaluate further hydrodynamic performance (Elshaw et al., 2016 ). The overall conceptual framework and the applications of the computational approach in wastewater treatment are presented in Fig. 4 .

7.3 Computational Artificial Intelligence Approach in Wastewater Treatment

Several studies were obtained by researchers to implement computer-based artificial techniques, which provide fast and rapid automated monitoring of water quality tests such as BOD and COD. Recently, Nourani et al. ( 2018 ) explores the possibility of wastewater treatment plant by using three different kinds of artificial intelligence methods, i.e., feedforward neural network (FFNN), adaptive neuro-fuzzy inference system (ANFIS), and support vector machine (SVM). Several measurements were done in terms of effluent to tests BOD, COD, and total nitrogen in the Nicosia wastewater treatment plant (NWWTP) and reported high-performance efficiency of artificial intelligence (Nourani et al., 2018 ).

7.4 Remote sensing and Geographical Information System

Since the implementation of satellite technology, the initiation of new methods and tools became popular nowadays. The futuristic approach of remote sensing and GIS technology plays a crucial role in the identification and locating of the water polluted area through satellite imaginary and spatial data. GIS analysis may provide a quick and reasonable solution to develop atmospheric correction methods. Moreover, it provides a user-friendly environment, which may support complex spatial operations to get the best quality information on water quality parameters through remote sensing (Ramadas & Samantaray, 2018 ).

8 Applications of Treated Wastewater

8.1 scope in crop irrigation.

Several studies have assessed the impact of the reuse of recycled/treated wastewater in major sectors. These are agriculture, landscapes, public parks, golf course irrigation, cooling water for power plants and oil refineries, processing water for mills, plants, toilet flushing, dust control, construction activities, concrete mixing, and artificial lakes (Table 5 ). Although the treated wastewater after secondary treatment is adequate for reuse since the level of heavy metals in the effluent is similar to that in nature (Ayers & Westcot, 1985 ), experimental evidences have been found and evaluated the effects of irrigation with treated wastewater on soil fertility and chemical characteristics, where it has been concluded that secondary treated wastewater can improve soil fertility parameters (Mohammad & Mazahreh, 2003 ). The proposed model (Fig. 3 ) is tested partially previously at a laboratory scale by treating the wastewater (from sewage, sugar, and paper industry) in an ultrasonic bath (Kesari et al., 2011a , b ; Kesari & Behari, 2008 ; Kumar et al., 2010 ). Advancing it with ultraviolet and ozone treatment has modified this in the proposed model. A recent study shows that the treated water passed quality measures suited for crop irrigation (Bhatnagar et al., 2016 ). In Fig. 3 , a model is proposed including all three (UV, US, nanoparticle, and ozone) techniques, which have been tested individually as well as in combination (US and nanoparticle) (Kesari et al., 2011a , b ) to obtain the highest water quality standards acceptable for irrigation and even drinking purposes.

A wastewater-irrigated field is a major source of essential and non-essential metals contaminants such as lead, copper, zinc, boron, cobalt, chromium, arsenic, molybdenum, and manganese. While crops need some of these, the others are non-essential metals, toxic to plants, animals, and humans. Kanwar and Sandha ( 2000 ) reported that heavy metal concentrations in plants grown in wastewater-irrigated soils were significantly higher than in plants grown in the reference soil in their study. Yaqub et al. ( 2012 ) suggest that the use of US is very effective in removing heavy or toxic metals and organic pollutants from industrial wastewater. However, it has been also observed that the metals were removed efficiently, when UV light was combined with ozone (Samarghandi et al., 2007 ). Ozone exposure is a potent method for the removal of metal or toxic compounds from wastewater as also reported earlier (Park et al., 2008 ). Application of US, UV, and O 3 in combination lead to the formation of reactive oxygen species (ROS) that oxidize certain organics, metal ions and kill pathogens. In the process of advanced oxidizing process (AOP) primarily oxidants, electricity, light, catalysts etc. are implied to produce extremely reactive free radicals (such as OH) for the breakdown of organic matters (Oturan & Aaron, 2014 ). Among the other AOPs, ozone oxidization process is more promising and effective for the decomposition of complex organic contaminants (Xu et al., 2020 ). Ozone oxidizes the heavy metal to their higher oxidation state to form metallic oxides or hydroxides in which they generally form limited soluble oxides and gets precipitated, which are easy to be filtered by filtration process. Ozone oxidization found to be efficient for the removal of heavy metals like cadmium, chromium, cobalt, copper, lead, manganese, nickel, and zinc from the water source (Upadhyay & Srivastava, 2005 ). Ultrasonic-treated sludge leads to the disintegration of biological cells and kills bacteria in treated wastewater (Kesari, Kumar, et al., 2011a ; Kesari, Verma, & Behari, 2011b ). This has been found that combined treatment with ultrasound and nanoparticles is more effective (Kesari, Kumar, et al., 2011a ). Ultrasonication has the physical effects of cavitation inactivate and lyse bacteria (Broekman et al., 2010 ). The induced effect of US, US, or ozone may destroy the pathogens and especially during ultrasound irradiation including free-radical attack, hydroxyl radical attack, and physical disruption of cell membranes (Kesari, Kumar, et al., 2011a ; Phull et al., 1997 ; Scherba et al., 1991 ).

8.2 Energy and Economy Management

Municipal wastewater treatment plants play a major role in wastewater sanitation and public health protection. However, domestic wastewater has been considered as a resource or valuable products instead of waste, because it has been playing a significant role in the recovery of energy and resource for the plant-fertilizing nutrients like phosphorus and nitrogen. Use of domestic wastewater is widely accepted for the crop irrigation in agriculture and industrial consumption to avoid the water crisis. It has also been found as a source of energy through the anaerobic conversion of the organic content of wastewater into methane gas. However, most of the wastewater treatment plants are using traditional technology, as anaerobic sludge digestion to treat wastewater, which results in more consumption of energy. Therefore, through these conventional technologies, only a fraction of the energy of wastewater has been captured. In order to solve these issues, the next generation of municipal wastewater treatment plants is approaching total retrieval of the energy potential of water and nutrients, mostly nitrogen and phosphorus. These plants also play an important role in the removal and recovery of emerging pollutants and valuable products of different nature like heavy and radioactive metals, fertilizers hormones, and pharma compounds. Moreover, there are still few possibilities of improvement in wastewater treatment plants to retrieve and reuse of these compounds. There are several methods under development to convert the organic matter into bioenergy such as biohydrogen, biodiesel, bioethanol, and microbial fuel cell. These methods are capable to produce electricity from wastewater but still need an appropriate development. Energy development through wastewater is a great driver to regulate the wastewater energy because it produces 10 times more energy than chemical, thermal, and hydraulic forms. Vermicomposting can be utilized for stabilization of sludge from the wastewater treatment plant. Kesari and Jamal ( 2017 ) have reported the significant, economical, and ecofriendly role of the vermicomposting method for the conversion of solid waste materials into organic fertilizers as presented in Fig. 5 . Solid waste may come from several sources of municipal and industrial sludge, for example, textile industry, paper mill, sugarcane, pulp industry, dairy, and intensively housed livestock. These solid wastes or sewage sludges have been treated successfully by composting and/or vermicomposting (Contreras-Ramos et al., 2005 ; Elvira et al., 1998 ; Fraser-Quick, 2002 ; Ndegwa & Thompson, 2001 ; Sinha et al., 2010 ) Although collection of solid wastes materials from sewage or wastewater and further drying is one of the important concerns, processing of dried municipal sewage sludge (Contreras-Ramos et al., 2005 ) and management (Ayilara et al., 2020 ) for vermicomposting could be possible way of generating organic fertilizers for future research. Vermicomposting of household solid wastes, agriculture wastes, or pulp and sugarcane industry wastes shows greater potential as fertilizer for higher crop yielding (Bhatnagar et al., 2016 ; Kesari & Jamal, 2017 ). The higher amount of solid waste comes from agricultural land and instead of utilizing it, this biomass is processed by burning, which causes severe diseases (Kesari & Jamal, 2017 ). Figure 3 shows the proper utilization of solid waste after removal from wastewater; however, Fig. 5 showing greater possibility in fertilizer conversion which has also been discussed in detail elsewhere (Bhatnagar et al., 2016 ; Nagavallemma et al., 2006 )

figure 5

Energy production through wastewater (reproduced from Bhatnagar et al., 2016 ; Kesari & Jamal, 2017 )

9 Conclusions and future perspectives

In this paper, we have reviewed environmental and public health issues associated with the use of untreated wastewater in agriculture. We have focused on the current state of affairs concerning the wastewater treatment model and computational approach. Given the dire need for holistic approaches for cultivation, we proposed the ideas to tackle the issues related to wastewater treatment and the reuse potential of the treated water. Water resources are under threat because of the growing population. Increasing generation of wastewater (municipal, industrial, and agricultural) in developing countries especially in India and other Asian countries has the potential to serve as an alternative of freshwater resources for reuse in rice agriculture, provide appropriate treatment, and distribution measures are adopted. Wastewater treatment is one of the big challenges for many countries because increasing levels of undesired or unknown pollutants are very harmful to health as well as environment. Therefore, this review explores the ideas based on current and future research. Wastewater treatment includes very traditional methods by following primary, secondary, and tertiary treatment procedures, but the implementation of advanced techniques is always giving us a big possibility of good water quality. In this paper, we have proposed combined methods for the wastewater treatment, where the concept of the proposed model works on the various types of wastewater effluents. The proposed model not only useful for wastewater treatment but also for the utilization of solid wastes as fertilizer. An appropriate method for the treatment of wastewater and further utilization for drinking water is the main futuristic outcome. It is also highly recommendable to follow the standard methods and available guidelines provided WHO. In this paper, the proposed role of the computational model, i.e., artificial intelligence, fluid dynamics, and GIS, in wastewater treatment could be useful in future studies. In this review, health concerns associated with wastewater irrigation for farmers and irrigated crops consumers have been discussed.

The crisis of freshwater is one of the growing concerns in the twenty-first century. Globaly, about 330 km 3 of municipal wastewater is generated annually (Hernández-Sancho et al., 2015 ). This data provides a better understanding of why the reuse of treated wastewater is important to solve the issues of the water crisis. The use of treated wastewater (industrial or municipal wastewater or Seawater) for irrigation has a better future for the fulfillment of water demand. Currently, in developing countries, farmers are using wastewater directly for irrigation, which may cause several health issues for both farmers and consumers (crops or vegetables). Therefore, it is very imperative to implement standard and advanced methods for wastewater treatment. A local assessment of the environmental and health impacts of wastewater irrigation is required because most of the developed and developing countries are not using the proper guidelines. Therefore, it is highly required to establish concrete policies and practices to encourage safe water reuse to take advantage of all its potential benefits in agriculture and for farmers.

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All the authors are highly grateful to the authority of the respective departments and institutions for their support in doing this research. The author VT would like to thank Science & Engineering Research Board, New Delhi, India (Grant #ECR/2017/001809). The Author RS is thankful to the University Grants Commission for the National Fellowship (201819-NFO-2018-19-OBC-UTT-78476).

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Kavindra Kumar Kesari and Ramendra Soni contributed equally to this work.

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Department of Applied Physics, Aalto University, Espoo, Finland

Kavindra Kumar Kesari & Janne Ruokolainen

Department of Molecular and Cellular Engineering, Sam Higginbottom University of Agriculture, Technology and Sciences, Naini, Allahabad, India

Ramendra Soni, Jonathan A. Lal & Vijay Tripathi

Department of Health Informatics, College of Public Health and Health Informatics, Qassim University, Al Bukayriyah, Saudi Arabia

Qazi Mohammad Sajid Jamal

Department of Computational Biology and Bioinformatics, Sam Higginbottom University of Agriculture, Technology and Sciences, Naini, Allahabad, India

Pooja Tripathi

Department of Biotechnology, School of Engineering & Technology, Sharda University, Greater Noida, UP, India

Niraj Kumar Jha

Department of Bioengineering, Faculty of Engineering, Integral University, Lucknow, India

Mohammed Haris Siddiqui

Department of Forestry, NERIST, Nirjuli, Arunachal Pradesh, India

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Kesari, K.K., Soni, R., Jamal, Q.M.S. et al. Wastewater Treatment and Reuse: a Review of its Applications and Health Implications. Water Air Soil Pollut 232 , 208 (2021). https://doi.org/10.1007/s11270-021-05154-8

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Water Recycling Essay

Introduction, the safety of drinking recycled water, risks associated with using reclaimed water, recycled water saves fresh potable water, reference list.

Recycled water is obtained from waste water and contaminated water that has been subjected to thorough treatment to ensure that it is proper for use for different purposes. A major benefit of recycled water is offering a sustainable and dependable source of water while decreasing demands on water provision that is brought about by the rising population (Hurlimann 2011).

To make sure that the rising population gets adequate water to satisfy all their requirements, there is a need for recycling of water and enlarging the application of reclaimed water. This paper seeks to determine if recycled water is safe for drinking.

  • It is assessed to avoid risk for human health. If the right procedure is followed, recycling of water makes it safe for drinking (Mankad & Tapsuwan 2011). Regular checking and treatment is necessary to make sure that recycled water is suitable for human consumption. For instance, the designated regulatory bodies in every Australian state endorse water systems to guarantee its safety for the intended purpose. The regulatory bodies are typically the departments accountable for safety and environment. They evaluate the degree of danger to human beings and the surroundings to establish whether a water recycling plan should be endorsed.
  • There is no instance where thoroughly recycled water caused illness. Reclaimed water has not brought about any disease anywhere across the globe. This has paved way for Australia as well as other countries to boost their dependence on recycled water (Burton et al. 2007).
  • Current methods make recycled water safe for drinking. Contemporary water recycling practices have eradicated microbial organisms to a degree that they are harmless to humans. On this note, there is a high chance of applying recycled water for different purposes in addition to drinking. Currently, science is concentrating on boosting the effectiveness of water recycling practices through reduction of costs, as well as greenhouse gases (Pelusey & Pelusey 2006).
  • Doubt. For a long time, it has been possible to convert sewage to safe, drinking water and this has acted as an excellent solution for water-scarce areas (Brown, Farrelly & Keath 2009). Nevertheless, this technology is not extensively applied, and even in some areas where it is applied, nobody in reality drinks the recycled water, not directly in any case. Many people still doubt the safety of recycled water for drinking.
  • Psychological point of view. The psychological aspect is what makes people not directly drink recycled water, since people are hesitant to consume anything that they know has come from the toilet. Though recycled water may not be harmful, it may not auger well with people’s mindset after knowing that they have for once drunk it (Dolnicar & Hurlimann 2011). Even though recycling of water removes the contaminants, it is not able to detach its initial uniqueness as sewage.
  • Recycled water is meant for non-potable functions. Reclaimed water is former sewage with contaminants removed and is employed for applications like irrigation. The aim of recycling is water conservation and not releasing recycled water for human consumption.
  • Presence of pathogens. The description of recycled water as applied by Friedler and Hadari (2006) is the outcome of sewage reclamation that satisfies water value necessities for eco-friendly substance, suspended stuff, and pathogens. In other conventional application, recycled water denotes water that has not been highly purified with the purpose of providing a means of conserving potable water; this water is instead used for agriculture and other uses like laundry (Hurlimann & McKay 2007).
  • Poor assessment standards. The states regulate recycled water and not the Environmental Protection Agency (EPA). Recent studies have proved that recycled water poses stern public health issues concerning pathogens in it that are not detected by the presently employed tests (Birks & Hills 2007). Moreover, the present tests fail to regard connections of heavy metals and pharmaceutics, which could promote the development of drug resistant microbes in recycled water obtained from sewage.
  • Cost. The outlay on recycling water surpasses that of treating fresh water in different areas across the globe, where there is plenty of water (Kemp et al. 2012). Nevertheless, recycled water is normally distributed to people at a lower cost to persuade them to make use of it. Though, in most cases, recycled water is not used for drinking, it saves drinking water that could otherwise have been used for other purposes as little or no potable water will be employed for non-drinking purposes.
  • Rich in nutrients. In most instances, recycled water is rich in nutrients like phosphorus and nitrogen that supports the growing crops in cases of its use in irrigation (Jarwal 2006). In this case, it turns out better and replaces drinking water that could otherwise have been used.

Breaking the characteristic of recycled water as water obtained from sewage and minimizing the difference between recycled water and fresh tap water may assist in the acceptance of recycled water even for potable purposes (Binnie, Kimber & Water 2009). Moreover, a different solution could be sending of properly tested recycled water into people’s taps for their use without initially informing them.

If people are then taught of its safety and it is proved to them through testing it, they may accept it without doubt. Nevertheless, recycled water must undergo thorough assessment and testing to make sure that it is suitable for drinking before it can be released for human consumption. To sum it up, whether recycled water is used for potable or non-potable purposes, its benefits cannot be underestimated (Upadhyaya & Moore 2012).

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Mankad, A & Tapsuwan, S 2011, ‘Review of socio-economic drivers of community acceptance and adoption of decentralised water systems’, Journal of Environmental Management , vol. 92, no. 3, pp. 380-391. Web.

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Steps of The Wastewater Treatment Process

  • Categories: Agriculture Water Pollution Water Quality

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Words: 1105 |

Published: Dec 5, 2018

Words: 1105 | Pages: 2 | 6 min read

Table of contents

Introduction, the steps of the wastewater treatment process, the environmental and health significance, the role of technological advancements.

  • Preliminary Treatment : The first step involves the removal of large objects and debris, such as sticks, leaves, and plastics, through screens or gratings. This helps protect downstream equipment from damage and ensures that smaller particles can be effectively removed in subsequent treatment stages.
  • Primary Treatment : In this phase, the wastewater is allowed to settle in large tanks, allowing solids to settle at the bottom and form sludge. This sludge is then removed and further treated or disposed of. Although primary treatment removes a significant portion of suspended solids, it is not effective in eliminating dissolved contaminants.
  • Secondary Treatment : Secondary treatment is designed to remove dissolved and suspended biological matter, such as organic materials and bacteria. It relies on microorganisms to break down these pollutants into less harmful substances. Common methods include activated sludge processes and trickling filters, which provide a habitat for beneficial bacteria to thrive and purify the water.
  • Tertiary Treatment : Also known as advanced treatment, this stage goes beyond secondary treatment to further polish the water quality. It involves additional processes like filtration, chemical treatment, and disinfection to remove remaining contaminants, including nutrients (e.g., nitrogen and phosphorus), pathogens, and trace chemicals. The treated water is now safe for release into the environment or for reuse.
  • Metcalf & Eddy, Inc., & Tchobanoglous, G. (2002). Wastewater Engineering: Treatment and Reuse. McGraw-Hill Education.
  • Cheremisinoff, N. P. (2019). Handbook of Water and Wastewater Treatment Technologies. Butterworth-Heinemann.
  • Tchobanoglous, G., Burton, F. L., & Stensel, H. D. (2002). Wastewater Engineering: Treatment and Reuse (Metropolitan Los Angeles Edition). McGraw-Hill.
  • Mara, D., & Horan, N. (2003). Handbook of Water and Wastewater Microbiology. Elsevier.
  • Khan, S. R., Tawabini, B. S., & Al-Zahrani, M. A. (2019). Advanced Technologies in Water and Wastewater Management. Springer.
  • US Environmental Protection Agency. (n.d.). Wastewater Technology Fact Sheet: Membrane Bioreactors.
  • World Health Organization. (2011). Guidelines for Drinking-water Quality. World Health Organization.

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Essay on Water Pollution: Samples in 200, 500 Words

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Essay on water pollution

Essay on Water Pollution: Water pollution occurs when human activities introduce toxic substances into freshwater ecosystems such as lakes, rivers, oceans, and groundwater, leading to the degradation of water quality. The combination of harmful chemicals with water has a negative impact on these ecosystems. 

Various human actions, particularly those affecting land, water, and underwater surfaces, contribute to this pollution, disrupting the natural supply of clean water and posing a significant danger to all forms of life, including humans.

Table of Contents

  • 1 What is Water Pollution?
  • 2.1 Contaminants 
  • 2.2 Solution 
  • 3.1 Reasons for Water Pollution
  • 3.2 Methods of Water Pollution Management
  • 3.3 Real-Life Encounter

Also Read: Types of Water Pollution

What is Water Pollution?

When many pollutants such as garbage, chemicals, bacteria, household waste, industrial waste, etc get mixed in the water resources and make the water unfit for cooking, drinking, cleaning, etc. it is known as water pollution. Water pollution damages the quality of water. lakes, water streams, rivers, etc may become polluted and eventually they will pollute the oceans. All this will directly or indirectly affect the lives of us humans and the animals deteriorating our health.

Essay on Water Pollution in 200 Words

Water is plentiful on Earth, present both above and beneath its surface. A variety of water bodies, such as rivers, ponds, seas, and oceans, can be found on the planet’s surface. Despite Earth’s ability to naturally replenish its water, we are gradually depleting and mishandling this abundant resource. 

Although water covers 71% of the Earth’s surface and land constitutes the remaining 29%, the rapid expansion of water pollution is impacting both marine life and humans. 


Water pollution stems significantly from city sewage and industrial waste discharge. Indirect sources of water pollution include contaminants that reach water supplies via soil, groundwater systems, and precipitation. 

Chemical pollutants pose a greater challenge in terms of removal compared to visible impurities, which can be filtered out through physical cleaning. The addition of chemicals alters water’s properties, rendering it unsafe and potentially lethal for consumption.


Prioritizing water infrastructure enhancement is vital for sustainable water management, with a focus on water efficiency and conservation. 

Furthermore, rainwater harvesting and reuse serve as effective strategies to curb water pollution. Reclaimed wastewater and collected rainwater alleviate stress on groundwater and other natural water sources. 

Groundwater recharge, which transfers water from surface sources to groundwater, is a well-known approach to mitigate water scarcity. These measures collectively contribute to safeguarding the planet’s water resources for present and future generations.

Here is a list of Major Landforms of the Earth !

Essay on Water Pollution in 500 Words

The term “water pollution” is employed when human or natural factors lead to contamination of bodies of water, such as rivers, lakes, and oceans. Responsible management is now imperative to address this significant environmental concern. The primary sources of water contamination are human-related activities like urbanization, industrialization, deforestation, improper waste disposal, and the establishment of landfills.

Reasons for Water Pollution

The availability of freshwater on our planet is limited, and pollution only increases this scarcity. Every year, a substantial amount of fresh water is lost due to industrial and various other types of pollution. Pollutants encompass visible waste items of varying sizes as well as intangible, hazardous, and lethal compounds.

Numerous factories are situated in proximity to water bodies, utilizing freshwater to transport their waste. This industrial waste carries inherent toxicity, jeopardizing the well-being of both plant and animal life. Individuals living close to polluted water sources frequently suffer from skin problems, respiratory ailments, and occasionally even life-threatening health conditions.

Water contamination is also intensified by urban waste and sewage, adding to the problem. Each household generates considerable waste annually, including plastic, chemicals, wood, and other materials. Inadequate waste disposal methods result in this refusal to infiltrate aquatic ecosystems like rivers, lakes, and streams, leading to pollution.

Methods of Water Pollution Management

Raising awareness about the causes and consequences of water pollution is crucial in significantly reducing its prevalence. Encouraging community or organizational clean-up initiatives on a weekly or monthly basis plays a pivotal role. 

To eradicate water contamination completely, stringent legislation needs to be formulated and diligently enforced. Rigorous oversight would promote accountability, potentially deterring individuals and groups from polluting. Each individual should recognize the impact of their daily actions and take steps to contribute to a better world for generations to come.

Real-Life Encounter

My affection for my town has always been heightened by its abundant lakes, rivers, and forests. During one of my walks alongside the river that flowed through my village, I was struck by the unusual hues swirling within the water. The once-familiar crystal-clear blue had been replaced by a murky brown shade, accompanied by a potent, unpleasant odour. Intrigued, I decided to investigate further, descending to the riverbank for a closer look at the source of the peculiar colours and smells. Upon closer inspection, I observed peculiar foam bubbles floating on the water’s surface.

Suddenly, a commotion behind me caught my attention, and I turned to witness a group of people hastening toward the river. Their frantic shouts and vigorous gestures conveyed their panic, prompting me to realize that a grave situation was unfolding. As the group reached the river, they were confronted with the distressing sight of numerous lifeless fish floating on the water’s surface. 

Following a comprehensive investigation, it was revealed that a local factory had been releasing toxic chemicals into the river, resulting in extensive pollution and the devastation of the ecosystem. This investigation left me stunned and disheartened, acknowledging the significant effort required to restore the river to its own form.

Related Reads:-     

A. Water pollution refers to the contamination of water bodies, such as rivers, lakes, oceans, and groundwater, due to the introduction of harmful substances. These substances can include chemicals, industrial waste, sewage, and pollutants that adversely affect the quality of water, making it unsafe for human consumption and harmful to aquatic life.

A. The primary sources of water pollution include city sewage and industrial waste discharge. Chemical contaminants from factories and agricultural runoff, as well as oil spills and plastic waste, contribute significantly to water pollution. Runoff from paved surfaces and improper waste disposal also play a role in introducing pollutants into water bodies.

A. Water pollution has far-reaching consequences. It poses a threat to aquatic ecosystems by harming marine life, disrupting food chains, and damaging habitats. Additionally, contaminated water can lead to the spread of waterborne diseases among humans. Toxic chemicals in polluted water can cause serious health issues, affecting the skin, and respiratory systems, and even leading to long-term illnesses. 

This brings us to the end of our blog on Essay on Water Pollution. Hope you find this information useful. For more information on such informative topics for your school, visit our  essay writing  and follow  Leverage Edu

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What 11 billion people means for...

5 Ways We Waste Water

a sprinkler watering a lawn

Water is a resource that much of the developed world takes for granted, but that many in the developing world struggle to find enough of every day.

That struggle could spread as climate change and other manmade pressures change the availability of water around the globe, and as Earth's population grows ever larger, making the need for that resource even more acute.

The number of humans on the planet could reach 11 billion people by the end of the century, the United Nations projects, up from just over 7 billion people now. Already, more than 2 billion people face a water scarcity each month, but tremendous amounts of water are still wasted. [ What 11 Billion People Mean for Water Scarcity ]

From lawns to flood irrigation, here are five ways that people waste water and some ways to reduce that waste.

Agriculture uses about 70 percent of the available freshwater on the planet. Around the world, most farming relies on flood irrigation — where fields are drenched with water and the excess runs off into nearby streams and rivers.

But flood irrigation wastes tons of water and can pollute waterways with fertilizers, creating dead zones in the ocean (where oxygen is used up and not available for marine creatures) and contributing to algal blooms, which can be toxic to marine life.

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Some regions, such as Israel, have moved to highly efficient drip irrigation, which directs water right onto the roots of the plant. But such systems are expensive to implement and don't work for all crops, so many regions will probably shift toward intermediate solutions such as sprinklers, which produce less waste runoff, and covering crops to prevent water evaporation.

Lawns are one of the thirstiest water hogs in cities and towns. While lawns may be appropriate in some areas, most green expanses aren't made of local grasses adapted to grow in the area. And the vast majority of manicured front yards require hefty watering to flourish.

As cities tighten their belts, some areas may require residents to water lawns less frequently or forgo lawn-watering altogether. In particularly arid regions, that may mean a lawn of cacti or rocks, whereas other areas may rip out the water-hungry grass species, such as St. Augustine, and replace them with mixtures of native grasses that guzzle less water. As a bonus, many of these native grasses are softer and less itchy than the old standbys.

Poor crop choice

As the population grows, it doesn't make sense for desert-dwellers to grow thirsty crops such as cotton or raise cattle, which requires much more water than producing an equivalent weight of wheat or potatoes.

As the planet becomes drier, countries will have to shift their economies, so that drier regions produce less thirsty products and wetter regions make water-hungry products such as beef .

Newer plants

But simply switching which crops are produced may not be enough for some regions of the world. Instead, they may need to manipulate the plants own systems' for dealing with drought to increase production.

One way to do that is to water crops less during certain parts of the harvest. The plants then direct more growth into the fruit, away from leaves and stems. That means farmers can grow more crops with less water. 

Flushed down the toilet

One of the biggest sources of usable water is treated wastewater. After people brush their teeth, wash their vegetables or flush the toilet, most of that water is treated and sanitized.

While that water isn't really suitable for a big glass of water (unless you're on the International Space Station ), much of it could be put to use watering crops, freeing up freshwater for drinking. Currently, the United States treats 70 percent of its wastewater, but only uses 4 percent of that amount. Increasing the wastewater usage would provide more water for everyone.

Follow Tia Ghose on Twitter  and Google+ .   Follow   LiveScience @livescience , Facebook   & Google+ . Original article on  LiveScience .

Tia Ghose

Tia is the managing editor and was previously a senior writer for Live Science. Her work has appeared in Scientific American, Wired.com and other outlets. She holds a master's degree in bioengineering from the University of Washington, a graduate certificate in science writing from UC Santa Cruz and a bachelor's degree in mechanical engineering from the University of Texas at Austin. Tia was part of a team at the Milwaukee Journal Sentinel that published the Empty Cradles series on preterm births, which won multiple awards, including the 2012 Casey Medal for Meritorious Journalism.

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essay in waste water


Essay on Clean Water and Sanitation

Students are often asked to write an essay on Clean Water and Sanitation in their schools and colleges. And if you’re also looking for the same, we have created 100-word, 250-word, and 500-word essays on the topic.

Let’s take a look…

100 Words Essay on Clean Water and Sanitation

Importance of clean water.

Clean water is vital for life. Every living organism needs it for survival. It helps in digestion, removes toxins, and keeps us hydrated. Without clean water, we risk diseases.

Role of Sanitation

Sanitation is as important as clean water. It prevents the spread of germs, ensuring we stay healthy. Good sanitation practices include proper waste disposal and maintaining cleanliness.

Link Between Clean Water and Sanitation

Clean water and sanitation are interconnected. Contaminated water can lead to poor sanitation, and vice versa. Hence, both are essential for a healthy life.

250 Words Essay on Clean Water and Sanitation


Clean water and sanitation are fundamental components of human health and wellbeing. They are deeply intertwined with socioeconomic development, environmental sustainability, and human dignity.

The Importance of Clean Water

Water is the lifeblood of our planet. It is essential for maintaining biodiversity, facilitating agricultural processes, and supporting human life. However, the quality of this precious resource is threatened by pollution, overexploitation, and climate change. Access to clean water is not just about quenching thirst; it’s about ensuring the health of individuals and communities. Waterborne diseases, often a result of poor water quality, account for substantial morbidity and mortality worldwide.

Sanitation: More than Hygiene

Sanitation extends beyond personal hygiene. It involves the management of human waste, solid waste, and wastewater. Proper sanitation practices reduce the incidence of diseases, enhance the quality of life, and contribute to social and economic development. Inadequate sanitation is a pressing issue in many parts of the world, leading to serious public health crises.

Linking Clean Water and Sanitation

The connection between clean water and sanitation is undeniable. Contaminated water sources due to poor sanitation practices can lead to the spread of diseases like cholera, dysentery, and typhoid. Therefore, efforts to improve water quality must go hand in hand with improving sanitation facilities.

The challenges surrounding clean water and sanitation are formidable, but not insurmountable. Through concerted efforts from governments, communities, and individuals, we can ensure access to these fundamental human rights for everyone, thereby paving the way for a healthier, more sustainable world.

500 Words Essay on Clean Water and Sanitation

Clean water and sanitation are fundamental to human health and well-being. Despite being recognized as a human right by the United Nations, millions of people worldwide still lack access to these basic necessities. The importance of clean water and sanitation cannot be overstated, as they play a crucial role in preventing disease, promoting health, and improving overall quality of life.

Water is a vital resource for all forms of life. However, clean and safe drinking water is not universally available. Contaminated water can transmit diseases such as diarrhea, cholera, dysentery, typhoid, and polio, leading to significant morbidity and mortality, particularly in developing countries. Furthermore, the lack of clean water can impede social and economic development, as individuals may spend significant time and effort obtaining water, rather than engaging in productive activities or education.

The Necessity of Sanitation

Sanitation, the provision of facilities and services for the safe disposal of human waste, is equally important. Poor sanitation can lead to the contamination of drinking water sources and the environment, resulting in a range of health problems. Moreover, inadequate sanitation facilities can compromise personal safety and dignity, particularly for women and girls. Improved sanitation contributes to social development by enhancing people’s living conditions and dignity, and to economic development by reducing healthcare costs and improving productivity.

Challenges and Solutions

Despite the critical importance of clean water and sanitation, numerous challenges hinder universal access. These include inadequate infrastructure, lack of funding, and insufficient awareness about the importance of hygiene. Addressing these challenges requires concerted efforts from governments, non-governmental organizations, and communities.

Infrastructure development is crucial for providing clean water and sanitation facilities, particularly in rural and marginalized areas. This includes building water purification systems, sewage treatment plants, and toilets. However, such initiatives require significant financial resources. Therefore, increased investment from both public and private sectors is necessary.

Education and awareness programs can also play a vital role in improving water and sanitation conditions. By educating communities about the importance of hygiene and the risks associated with contaminated water and poor sanitation, we can encourage behavior change and promote the utilization of water and sanitation facilities.

In conclusion, clean water and sanitation are not just basic human needs, but they are also fundamental human rights. Despite the challenges, achieving universal access to clean water and sanitation is possible through infrastructure development, increased funding, and education. By ensuring everyone has access to these basic services, we can significantly improve global health, foster social and economic development, and ultimately, create a more equitable world.

That’s it! I hope the essay helped you.

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Wastewater essay.

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This Wastewater Essay example is published for educational and informational purposes only. If you need a custom essay or research paper on this topic, please use our writing services. EssayEmpire.com offers reliable custom essay writing services that can help you to receive high grades and impress your professors with the quality of each essay or research paper you hand in.

Wastewate r is not just sewage. Defined as domestic, industrial, agricultural, and storm water flows that drain into sewage collection systems, wastewater reflects the geographic character of communities and environments. Sewage, or refuse liquid and waste matter produced by residences and commerce, is often labeled “wastewater;” yet sewage is technically limited to discharge channeled by sewer pipes. Wastewater, however, pulls from a broader array of social and environmental sources: Storm drains, overflowing creeks, septic tank leaks, and runoff from parking lots and pavements, the crop field, and the industrial dump site. Wastewater quality and quantity are thus related to the patterns and politics of water availability, governance, and waste-making practices.

Wastewater composition is approximately 99 percent water by weight, but it contains numerous biological, chemical, and material compounds ranging from pathogenic bacteria to pharmaceutical compounds and trash. In large quantities, these compounds produce adverse effects on human and ecological systems. For example, in municipalities with combined storm drains and sewer infrastructure, storm water mixes with wastewater after severe rainfall events, often resulting in combined sewer overflows. These overflows, in tandem with renegade wastewater flows and increased urban runoff, frequently result in poor water quality. For this reason, many laws and regulations (such as the U.S. Clean Water Act) mandate wastewater treatment to decrease environmental contamination and improve water quality.

Wastewater treatment plants intervene at critical points in the water cycle. Although septic tanks are still common in rural areas, the majority of municipal wastewater is treated in large-scale plants. There are no holidays for wastewater treatment: Most plants operate 24 hours per day, seven days per week. Treatment plants are designed to reduce harmful substances and pollutants in wastewater before flows are returned to rivers, oceans, or the broader environment. In general, there are three stages of wastewater treatment: (1) primary treatment (physical removal of floatable and settleable solids; (2) secondary treatment (biological removal of dissolved solids); and (3) tertiary or advanced treatment (removal of nutrients and chemicals).

Primary treatment extracts solid particulates and oils from wastewater. First, influent is screened to remove large objects, such as rocks, corpses, or condoms, which could plug sewer lines or block tank inlets. Next, flows enter a grit chamber and decrease in velocity, allowing sand and grit to fall out. Macerators (revolving cylinders with rotating knife edges) are sometimes used in place of screens to cut solids into smaller, collectable particles. Finally, wastewater is slowly moved through sedimentation tanks (also called clarifiers or settling tanks). Fecal solids settle out in the tanks and are pumped away, while oils, grease, and plastics float to the surface and are skimmed off.

Secondary treatment typically utilizes aerobic biological processes to further degrade the supernatant (remaining flows after primary treatment) and convert nonsettleables to settleable solids. This level of treatment removes approximately 85 percent of the total suspended solids (TSS) in wastewater and is the minimum level of treatment required by the U.S. Clean Water Act. Secondary treatment is a balance of engineering, siting politics, budgets, and local environmental conditions. Secondary systems are classified either as suspended growth or fixed film, although systems may use elements of both. The most common suspended growth option, activated sludge, uses microorganisms to break down organic material via aeration, agitation, and settling. The sludge, which contains fungi, protozoa, and aerobic bacteria, is continually recirculated through the aeration basins to speed the process of organic decomposition. In general, suspended growth systems require less space, but may not be able to handle shocks in biological loading.

In many older plants, fixed film processes are used. For example, wastewater is sprayed into the air (a process called aeration) and allowed to trickle down through coarse media, such as beds of stones or plastic. Microorganisms, attached to and growing on the media, break down organic material as wastewater seeps past. These secondary systems provide higher removal rates for BOD (biological oxygen demand: an indicator of pollutant quality) and are better able to cope with quantity variability, but require large tracts of land and are often rejected by nearby communities for aesthetic and political reasons.

Tertiary treatment is the polishing stage of wastewater treatment. In response to successful litigation by environmental groups and higher regulatory standards, many wastewater facilities increasingly employ advanced tertiary methods to improve effluent quality. Tertiary treatment includes a broad range of methods, such as physical, biological, or chemical processes to remove nitrogen and phosphorus, carbon adsorption to remove chemicals, and disinfection using chlorine, ozone, or ultraviolet light.

Tertiary treatment is needed to produce reclaimed water: Highly treated and recycled wastewater commonly used for nonpotable and nonagricultural uses (such as the irrigation of parks and public spaces). However, due to increasing population, water consumption patterns, and demand for new supplies, many areas are now considering broader uses for reclaimed water. For instance, water providers in Orange County, California, use reclaimed water for indirect potable recharge: The method of blending reclaimed water with other drinking sources through groundwater recharge or reservoir augmentation. For better or for worse, the debates over reclaimed water use in the municipal sector have focused attention on wastewater treatment plants as key links between water quality and quantity.

Despite advances in engineering and treatment, problems associated with wastewater pollution, management, and disposal continue to plague communities and environments worldwide. Approximately 2.6 billion people lack access to improved sanitation: A broad category that includes ventilated pit latrines, composting toilets, and toilets connected to septic tanks or piped sewers. Although global sanitation coverage rose from 49 percent in 1990 to 58 percent in 2002, access to potable water supply still outstrips sanitation access. The United Nations (UN) Millennium Development Goals aim to halve the proportion of people without access to basic sanitation by 2015; yet the UN estimates that if the 1990-2002 sanitation trend continues, roughly 2.4 billion people will be without improved sanitation in 2015, almost as many as are without today.

Developed nations have not escaped the problems of wastewater either. Many European and North American countries feature excellent rates of sanitation access, well-established institutions, and strong regulatory mechanisms; yet, non-pointsource pollution, high rates of water consumption, and excessive waste-generating practices have contributed to wastewater problems in many major cities. For example, on a daily basis, California sends billions of gallons of partially treated sewage into the Pacific Ocean. The sewage usually meets state and federal effluent standards, but increased nutrient loading, urban runoff, and wastewater discharges have caused massive algae blooms, turning coastal waters into toxic soup for marine mammals, fisheries, and recreational users.


  • Robert L. Droste, Theory and Practice of Water and Wastewater Treatment (J. Wiley, 1997);
  • George T chobanoglous, Franklin L. Burton, and David Stensel, Wastewater Engineering: Treatment and Reuse (McGraw-Hill, 2003);
  • United Nations (UN) World Wide Water Assessment Program (WWAP), Water, A Shared Responsibility: The United Nations World Water Development Report 2 (UN Educational, Scientific, and Cultural Organization and Berghahn Books, 2006);
  • Kenneth R. Weiss, “Sentinels Under Attack,” Los Angeles Times (July 31, 2006).
  • How to Write an Essay
  • Essay Topics
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Environment Essay Examples

Essay on Save Water Save Life

Water is the most important and valuable natural resource on Earth. It sustains all life. There is no life without water. Water is not only important for human beings but for the entire ecosystem. Without enough water, the existence of humans, as well as animals, is next to impossible. After fresh air, water is the second most important natural resource for the survival of any living being. 

Water is necessary for the survival of each living creature on this planet, be it a small worm, plant, or full-grown tree.  Animals and plants  cannot survive without water. About 71% of Earth’s surface is covered with water. Unfortunately, only 3% of the water available  is freshwater. About two-thirds of the freshwater lies in the form of frozen glaciers and ice caps. The rest of the small portion is available in the form of groundwater and surface water. 

We totally depend on water for multiple purposes. Water is used in agriculture for the irrigation of crops. We use water for drinking, cooking, cleaning, bathing, and other domestic purposes. Water is used for recreational activities. In industries, water is used as a coolant, solvent and also used in other manufacturing purposes. Hydroelectricity is generated with the help of water. Water is also used for navigation and transportation of goods. This tells us how water is the most essential component of life and every drop of water is vital for sustenance. Therefore, water conservation is important to save life on this planet.

Importance of Water:

The basic use of water is drinking, bathing, agriculture, irrigation, hospitality, factories, etc.

Water helps in blood circulation and improves metabolism in the human body

The entire aquatic ecosystem is located in water. It is a home for all the aquatic animals

Water is a major source of transportation after land and air.

Water aids in saliva secretion and oxygen delivery to our bodily cells.

 Some countries have abundant water resources for their residents and serve        the people, whereas others lack natural resources even for survival.

Depletion of fresh water has become a threat to our existence. According to some scientists, the quantity and the quality of water are degrading day by day. Although Earth is covered with almost 71% of water, the quality is that we cannot use it in day-to-day life for domestic purposes. Water quality is so poor that people in some places are prone to several water-borne diseases such as Eluru, caused by contaminated water. 

These instances are eye-opening examples and should be taken seriously for better living conditions for us and our future generation.

Below are the Reasons for Shortage of Fresh Water:

Growth of population leads to excessive consumption of water. 

Daily excessive wastage of water.

The rapid growth of industries has increased the problem of proper disposal of waste material from them. The waste products from these industries contain extremely poisonous elements that are polluting the rivers and other water bodies. 

Pesticides and chemical fertilisers that are used to treat crops also pollute the fresh water. 

Sewage waste that is dumped into the rivers is making the water unsuitable for drinking and washing causing several water-borne diseases like cholera, jaundice and typhoid.  

Use of plastics and disposing them carelessly in the water bodies are affecting aquatic life and further disturbing the entire ecosystem.

Global warming is another major reason for the scarcity of water on earth. According to several types of research, because of global warming, the world will face more stress for water scarcity till the year 2050.

 We now need to be aware of the depletion of fresh water and take adequate    measures to stop this. 

Saving Water: Need of the Hour

Many places face extreme water scarcity due to extremely bad weather conditions, leading to less rainfall and groundwater depletion. In other parts of the world, groundwater is either unusable or overused. As the world's population is growing, so increase in industries and globalisation, causing groundwater to be overused and resulting in water scarcity.

The World Health Organisation (WHO) data shows that many people on this planet don't have access to clean and fresh drinking water. These situations are becoming worse day by day, and we need an immediate plan to control this situation. Various collective measures have to be taken by every individual on this planet and the government of every country to control water scarcity.

Government should impose some strict rules for the conservation of water. The government and the citizens have to take the initiative to create awareness and promote the “conservation of water.” One such initiative taken by the Modi government in India was “JANSHAKTI FOR JALSHAKTI.” This programme began as a means of working toward a brighter future.

Initiatives taken by Some State Governments:

The Punjab government contributed to saving water resources by avoiding waterlogging and fixing the drain  leakage.

The Rajasthan government has taken the initiative to construct small ponds, which  helped the local people of Rajasthan in many ways.

Villages of Telangana have constructed water tanks to conserve rainwater for future use.

These states are an inspiration, and others should also take a step forward to conserve and clean the water, water bodies, and groundwater.

Water saving should be and is the universal responsibility of every human being, living on this Earth.

There are many ways in which we can save water and reduce their pollution:

Be responsible to save water daily. Use only the required amount of water and avoid wastage. We should use water wisely.

We should use a washing machine to full capacity for washing clothes. 

We should not let the tap run while washing hands and face. 

We should water plants in the evening or early morning to minimise evaporation.

We should make provisions to store rainwater on rooftops and reuse the water for household purposes.

Bigger Communities and farmers should adapt to the practice of Rainwater harvesting. 

The industrial waste should be treated properly instead of dumping it into rivers.

We should stop using plastics and dispose of them in an adequate way.

We can make people aware about water problems by means of social campaigns and other ways.

 We should educate our children about water saving from an early age. 

Reusing the water is an important way to save and prevent the scarcity of water. Bathing water can be recycled and used for planting or cleaning.

Rainwater harvesting is the method of collecting rainwater and conserving them for future use.

Conservation of groundwater is another important method in the preservation of groundwater and using it in the future.

 Prevention of waterlogging.

We cannot imagine our lives without water. It is unfortunate that mankind has neglected this precious gift from God. Conservation of water is a necessity to save life. All living organisms on this planet need water to survive. If we do not give importance to saving or conservation of water then our future generations will face water scarcity.


FAQs on Save Water Save Life Essay

1. How to minimise wasting water?

We can minimise wasting water by using only the required amount of water.    We should not let the tap run while washing hands and face. Furthermore, checking for leaks in pipelines and getting them resolved in time and taking shorter baths and reducing the use of showers can also help.

2. When is World Water Day celebrated and why?

World Water Day is celebrated on 22nd March every year. It is celebrated to remind us of the importance of water and how we should minimise wastage of water.

3. Why is it important to save water?

It is important to save water because only 3% of available water is freshwater. Water is vital for the sustenance of living beings on this planet. If we don’t use water properly then our future generations will face the scarcity of water.

4. What methods should farmers adopt for irrigation?

The farmers should stop using pesticides and chemical fertilisers to minimise    pollution in water and adapt to the method of Rainwater harvesting.

5. How to save water daily?

We should close the tap tightly after use, use the required amount of water, check the water level in the tanks, and stop them from overflowing, making rainwater harvesting tunnels to save and reuse rainwater after its purification. These are some basic steps to save water at an individual level.

6. Where can I find more information on water and how to save water?

You can find more information, along with answers to your commonly asked questions, on the Vedantu website and mobile app. So, browse through them to get all your questions answered easily.

Water Conservation Essay

500+ words essay on water conservation.

Water makes up 70% of the earth as well as the human body. There are millions of marine species present in today’s world that reside in water. Similarly, humankind also depends on water. All the major industries require water in some form or the other. However, this precious resource is depleting day by day. The majority of the reasons behind it are man-made only. Thus, the need for water conservation is more than ever now. Through this water conservation essay, you will realize how important it is to conserve water and how scarce it has become.

water conservation essay

Water Scarcity- A Dangerous Issue

Out of all the water available, only three per cent is freshwater. Therefore, it is essential to use this water wisely and carefully. However, we have been doing the opposite of this till now.

Every day, we keep exploiting water for a variety of purposes. In addition to that, we also keep polluting it day in and day out. The effluents from industries and sewage discharges are dispersed into our water bodies directly.

Moreover, there are little or no facilities left for storing rainwater. Thus, floods have become a common phenomenon. Similarly, there is careless use of fertile soil from riverbeds. It results in flooding as well.

Therefore, you see how humans play a big role in water scarcity. Living in concrete jungles have anyway diminished the green cover. On top of that, we keep on cutting down forests that are a great source of conserving water.

Nowadays, a lot of countries even lack access to clean water. Therefore, water scarcity is a real thing. We must deal with it right away to change the world for our future generations. Water conservation essay will teach you how.

Get the huge list of more than 500 Essay Topics and Ideas

Water Conservation Essay – Conserving Water

Life without water is not possible. We need it for many things including cleaning, cooking, using the washroom, and more. Moreover, we need clean water to lead a healthy life.

We can take many steps to conserve water on a national level as well as an individual level. Firstly, our governments must implement efficient strategies to conserve water. The scientific community must work on advanced agricultural reforms to save water.

Similarly, proper planning of cities and promotion of water conservation through advertisements must be done. On an individual level, we can start by opting for buckets instead of showers or tubs.

Also, we must not use too much electricity. We must start planting more trees and plants. Rainwater harvesting must be made compulsory so we can benefit from the rain as well.

Further, we can also save water by turning off the tap when we brush our teeth or wash our utensils. Use a washing machine when it is fully loaded. Do not waste the water when you wash vegetables or fruit, instead, use it to water plants.

All in all, we must identify water scarcity as a real issue as it is very dangerous. Further, after identifying it, we must make sure to take steps to conserve it. There are many things that we can do on a national level as well as an individual level. So, we must come together now and conserve water.

FAQ of Water Conservation Essay

Question 1: Why has water become scarce?

Answer 1: Water has become scarce due to a lot of reasons most of which are human-made. We exploit water on a daily basis. Industries keep discharging their waste directly into water bodies. Further, sewage keeps polluting the water as well.

Question 2: How can we conserve water?

Answer 2: The government must plan cities properly so our water bodies stay clean. Similarly, water conservation must be promoted through advertisements. On an individual level, we can start by fixing all our leaky taps. Further, we must avoid showers and use buckets instead to save more water.

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Water Waste Management (Essay Sample)

Water is one of the most essential needs for a person to have a sustainable life. All creatures need water to progress and produce. Without it no one will exist, because our planet consists of mostly water therefore water gives us life. To have a sufficient supply of water we have to conserve. This is not an easy task especially in today’s era. Everything is commercialized and modernized to the point wherein natural conservation has been set aside. Increase in population is also one of the main reasons why water conservation becomes hard. As the number of people grows, the water becomes more polluted.

This is where water waste management comes in, it is the process of recycling water to be used again in a water system or to be disposed in an environmentally-conscious manner. The major problem in the modernized world is that every now and then infrastructures arise which makes it harder to recycle water because the sewage system becomes small. Sewage treatment is one of the major fields in water waste management. All that comes from your toilet, be it showers, baths, sinks etc. is directly generated into sewage systems. The wastewater that comes from industrial facilities is dangerous because it carries harmful pollutants that and if not handled with care, these pollutants turn into toxins that will cause illness or even death for millions of people on a global scale.

Another problem in the modern management is the small capacity of sewage system. Other cities also tend to direct the rain water into the sewage system that causes overflow in it. If the overflow happens, all the contaminants in the sewage will be spread in all parts of the city which is very harmful to the people. Sewage systems consist of pipes and pumps and have three stages of filtration. The first stage is separating solid waste from the water. Second stage is treating the water and removing microorganisms. Third stage is the process called microfiltration. In this stage the water is being treated and chemical additives are added into the water which eventually treats the liquid and transforms them into drinkable or usable water for our daily use.

Recycling water is no easy task; it takes a lot of time, effort, and investment in doing so. Wasted water will affect so many people’s lives. Dirty water is as harmful as poison when consumed by a person. We can aid in recycling water by researching on how to do simple filtration set-ups, conserve water when not in use, and properly segregate and dispose of garbage so as to not provide toxins in water.

There are two types of wastewater that we can recycle on our own. First is the black water that comes from our toilet. If you want to have your own sewage system, this black water can be regulated in a leach field. Second is the grey water, which comes from our sink. Grey water can be used in watering the plants, washing the tires of your car or even washing your garage. This type of waste water can be used in other chores but is not potable.

In doing your own waste water management at you home you can help the environment be clean. It will also lessen the work of sewage systems and it will save the world a lot of water. In order to live a happy and healthy life we should all take charge of our own cleanliness. Let us not take for granted the small things that will make our lives easier and for future generations who will inevitably use them.

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