essay in waste water

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Introduction & Top Questions

Direct discharge of sewage

Developments in sewage treatment.

Sources of water pollution
Types of sewage
Organic material
Suspended solids
Plant nutrients
Combined systems
Separate systems
Alternative systems
Primary treatment
Trickling filter
Activated sludge
Oxidation pond
Rotating biological contacter
Effluent polishing
Removal of plant nutrients
Land treatment
Clustered wastewater treatment systems
On-site septic tanks and leaching fields
Wastewater reuse
Improved treatment methods
Environmental considerations

How is sewage transformed into drinkable water?

What are the common pollutants present in wastewater?

How is wastewater processed at a sewage treatment facility, why is wastewater resource recovery important.

Rafael Nadal of Spain returns ball during second round match against Robin Haase of the Netherlands at Wimbledon in London, England on June 24, 2010

wastewater treatment

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Academia - Wastewater Treatment Design
Chemistry LibreTexts - Wastewater and Sewage Treatment
Food and Agriculture Organization of the United Nations - Wastewater treatment
National Center for Biotechnology Information - PubMed Central - Wastewater Treatment &Water Reclamation
USGS - Water Science School - Wastewater Treatment Water Use
Table Of Contents

What is wastewater?

Wastewater is the polluted form of water generated from rainwater runoff and human activities. It is also called sewage. It is typically categorized by the manner in which it is generated—specifically, as domestic sewage, industrial sewage, or storm sewage (stormwater).

How is wastewater generated?

Domestic wastewater results from water use in residences, businesses, and restaurants.
Industrial wastewater comes from discharges by manufacturing and chemical industries.
Rainwater in urban and agricultural areas picks up debris, grit, nutrients, and various chemicals, thus contaminating surface runoff water.

Wastewater contains a wide range of contaminants. The quantities and concentrations of these substances depend upon their source. Pollutants are typically categorized as physical, chemical, and biological. Common pollutants include complex organic materials, nitrogen- and phosphorus-rich compounds, and pathogenic organisms ( bacteria , viruses , and protozoa ). Synthetic organic chemicals, inorganic chemicals, microplastics, sediments, radioactive substances, oil, heat, and many other pollutants may also be present in wastewater.

Sewage treatment facilities use physical, chemical, and biological processes for water purification . The processes used in these facilities are also categorized as preliminary, primary, secondary, and tertiary. Preliminary and primary stages remove rags and suspended solids. Secondary processes mainly remove suspended and dissolved organics. Tertiary methods achieve nutrient removal and further polishing of wastewater. Disinfection, the final step, destroys remaining pathogens. The waste sludge generated during treatment is separately stabilized, dewatered, and sent to landfills or used in land applications.

Wastewater is a complex blend of metals, nutrients, and specialized chemicals. Recovery of these valuable materials can help to offset a community’s growing demands for natural resources. Resource recovery concepts are evolving, and researchers are investigating and developing numerous technologies. Reclamation and reuse of treated water for irrigation , groundwater recharge, or recreational purposes are particular areas of focus.

Recent News

wastewater treatment , the removal of impurities from wastewater, or sewage, before it reaches aquifers or natural bodies of water such as rivers , lakes , estuaries , and oceans . Since pure water is not found in nature (i.e., outside chemical laboratories), any distinction between clean water and polluted water depends on the type and concentration of impurities found in the water as well as on its intended use. In broad terms, water is said to be polluted when it contains enough impurities to make it unfit for a particular use, such as drinking, swimming, or fishing. Although water quality is affected by natural conditions, the word pollution usually implies human activity as the source of contamination. Water pollution , therefore, is caused primarily by the drainage of contaminated wastewater into surface water or groundwater , and wastewater treatment is a major element of water pollution control .

Historical background

Many ancient cities had drainage systems, but they were primarily intended to carry rainwater away from roofs and pavements. A notable example is the drainage system of ancient Rome . It included many surface conduits that were connected to a large vaulted channel called the Cloaca Maxima (“Great Sewer”), which carried drainage water to the Tiber River . Built of stone and on a grand scale, the Cloaca Maxima is one of the oldest existing monuments of Roman engineering.

There was little progress in urban drainage or sewerage during the Middle Ages. Privy vaults and cesspools were used, but most wastes were simply dumped into gutters to be flushed through the drains by floods. Toilets (water closets) were installed in houses in the early 19th century, but they were usually connected to cesspools, not to sewers . In densely populated areas, local conditions soon became intolerable because the cesspools were seldom emptied and frequently overflowed. The threat to public health became apparent. In England in the middle of the 19th century, outbreaks of cholera were traced directly to well-water supplies contaminated with human waste from privy vaults and cesspools. It soon became necessary for all water closets in the larger towns to be connected directly to the storm sewers. This transferred sewage from the ground near houses to nearby bodies of water. Thus, a new problem emerged: surface water pollution.

It used to be said that “the solution to pollution is dilution.” When small amounts of sewage are discharged into a flowing body of water, a natural process of stream self-purification occurs. Densely populated communities generate such large quantities of sewage, however, that dilution alone does not prevent pollution. This makes it necessary to treat or purify wastewater to some degree before disposal.

The construction of centralized sewage treatment plants began in the late 19th and early 20th centuries, principally in the United Kingdom and the United States . Instead of discharging sewage directly into a nearby body of water, it was first passed through a combination of physical, biological, and chemical processes that removed some or most of the pollutants. Also beginning in the 1900s, new sewage-collection systems were designed to separate storm water from domestic wastewater, so that treatment plants did not become overloaded during periods of wet weather.

After the middle of the 20th century, increasing public concern for environmental quality led to broader and more stringent regulation of wastewater disposal practices. Higher levels of treatment were required. For example, pretreatment of industrial wastewater, with the aim of preventing toxic chemicals from interfering with the biological processes used at sewage treatment plants, often became a necessity. In fact, wastewater treatment technology advanced to the point where it became possible to remove virtually all pollutants from sewage. This was so expensive, however, that such high levels of treatment were not usually justified.

Wastewater treatment plants became large, complex facilities that required considerable amounts of energy for their operation. After the rise of oil prices in the 1970s, concern for energy conservation became a more important factor in the design of new pollution control systems. Consequently, land disposal and subsurface disposal of sewage began to receive increased attention where feasible . Such “low-tech” pollution control methods not only might help to conserve energy but also might serve to recycle nutrients and replenish groundwater supplies.

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Essay on Water Conservation: Samples in 150, 200, 250 Words

Updated on
May 8, 2024

What makes you curious to write an essay on water conservation? This life-saving resource is essential for all forms of life on Earth. Water is the essential natural resource present on Earth. Out of the total water present on Earth, 97.5% is salt water and 2.5% is fresh water. 70% of the human body is made of water. But, with the growing population , and climatic crisis , we are facing the urgent need to conserve water.

Water conservation is a hot topic, if you need a sample essay on water conservation then, you are at the right place. In this blog post, we have covered essays on water conservation in 100, 200, and 250 words. Further we are also providing a sample piece of writing on essay on water conservation. So, stay tuned and read further to get some ideas about water conservation!

Table of Contents

1 Essay on Water Conservation in 100 Words
2 Essay on Water Conservation in 200 Words
3.1 Water Scarcity
3.2 Ways to Conserve Water
4 Short Essay on Water Conservation

Essay on Water Conservation in 100 Words

Water is crucial for all components of life which makes it a necessary resource for day-to-day activities. We use water for domestic activities like cooking, bathing, drinking, washing, etc. So, ultimately the consumption of water is very high. This makes it necessary to conserve water. Just as air, water is also important for life. Besides, water consumption, water pollution, and water scarcity are also some of the major water-related issues that need attention so that we can conserve water.

Every year we celebrate World Water Day on 22 March. This day is celebrated to spread awareness about the importance of water and run campaigns to conserve water on Earth. There are several ways to conserve water such as switching to showers, turning off taps when not in use, don’t pollute water bodies, storing rainwater, etc.

Essay on Water Conservation in 200 Words

Water is one of the Earth’s most precious resources. But the world is facing water scarcity. As per the SDA report 2022, around 2 billion people worldwide are lacking safe drinking water. This means they are more vulnerable to diseases and unhealthy life.

Apart from the increasing population, climatic change is also hampering the quality of water. Floods and Droughts are more frequent due to the vulnerability of climate, thereby increasing the need to conserve water.

Water conservation is vital to meet the growing global demand for fresh water. Water consumption is very high for agriculture, industry, and households. By conserving water, we can ensure that there is a surplus amount of water to use and avoid conflicts over this limited resource.

Water conservation helps to maintain a balance in the ecosystem because every living thing on this planet is directly associated with the use of water. Reducing water consumption reduces the energy footprint associated with water supply.

The best ways of water conservation are rainwater harvesting , installing water plants, reusing water for gardening purposes, turning off taps when not in use, proper irrigation, installing automatic tap shut-off devices, not polluting water sources, and many more.

If we don’t want to witness the world die due to water scarcity then, it’s high time to conserve water and save the planet and future generations.

Water Conservation Essay 250 Words

Water conservation is a crucial step in protecting the environment. It is an important compound that supports life on Earth. The world has been facing water-related disasters due to scarcity of freshwater. 70% of the earth as well as the human body is composed of water, but there is a limited amount of freshwater to use. Owing to the ever-increasing population, climatic changes, global warming, and pollution, the need for the conservation of water is increasing. To do so, it is our fundamental duty to conserve water by planting more trees, managing water plants, storing rainwater, and making smart use of water.

Water Scarcity

Water scarcity is a critical global issue that needs strict attention when the demand for freshwater exceeds the available supply of water. It can manifest in various ways, including a lack of access to clean drinking water, inadequate water for agriculture and industrial processes, and stressed or depleted natural water sources.

Here are some factors that contribute to water scarcity:

Climate change
Growing population
Global warming
Inefficient water management
Water pollution
Increasing demand
Poor irrigation techniques
Wastage of water, and much more.

Ways to Conserve Water

Conserving water is crucial to help address water scarcity and ensure a sustainable water supply for both present and future generations. You can contribute individually by taking small measures to conserve water like turning off the tap. Likewise, here are some ways to conserve water:

Drip irrigation technique
Soil management
Plantation of drought-tolerant crops
Apply Mulching
Recycle and reuse water
Rainwater harvesting
Desalination
Spread awareness to conserve water
Donate to the water cleaning campaign
Implement proper water management techniques.

Short Essay on Water Conservation

Find the sample of short essay on water conservation below:

Also Read: Essay on Save Environment: Samples in 100, 200, 300 Words

Water conservation is the individual or collective practice of efficient use of water. This helps in protecting the earth from the situation of water scarcity. We can individually contribute to water conservation by not wasting water, reducing the over-consumption of water, rainwater harvesting, etc. Water conservation is an important call because there is a limited amount of fresh water available on earth.

Here are 10 ways to save water. 1. Rainwater harvesting 2 Install water plants 3. Reuse water 4. Maintain proper water management plans 5. Fix the irrigation system 6. Use a bucket 7. Turn off the tap when not in use 8. Keep a regular check on pipe leakage 9. Do not pollute water bodies 10. Participate in water cleaning campaigns

Here are 5 points on the importance of water conservation: It helps the ecosystem; Water conservation is necessary for drought-prone areas; It helps reduce costs; Water conservation improves the quality of water; and Maintains the health of the aquatic ecosystem.

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Hi, I am Kajal, a pharmacy graduate, currently pursuing management and is an experienced content writer. I have 2-years of writing experience in Ed-tech (digital marketing) company. I am passionate towards writing blogs and am on the path of discovering true potential professionally in the field of content marketing. I am engaged in writing creative content for students which is simple yet creative and engaging and leaves an impact on the reader's mind.

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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

Introduction.

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

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

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.

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.

Happy studying!

Water Recycling Essay

To find inspiration for your paper and overcome writer’s block
As a source of information (ensure proper referencing)
As a template for you assignment

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).

Binnie, C, Kimber, M & Water, A 2009, Basic water treatment , 4th edn, Thomas Telford, London. Web.

Birks, R & Hills, S 2007, ‘Characterisation of indicator organisms and pathogens in domestic greywater for recycling’, Environmental monitoring and assessment , vol. 129, no. 3, pp. 61-69. Web.

Brown, R, Farrelly, M & Keath, N 2009, ‘Practitioner perceptions of social and institutional barriers to advancing a diverse water source approach in Australia’, Water Resources Development , vol. 25, no. 1, pp. 15-28. Web.

Burton, F, Leverenz, H, Tsuchihashi, R & Tchobanoglous, G 2007, Water reuse: issues, technologies, and applications , McGraw-Hill, New York. Web.

Dolnicar, S & Hurlimann, A 2011, ‘Water alternatives—who and what influences public acceptance?’, Journal of Public Affairs , vol. 11, no. 1, pp. 49-59. Web.

Friedler, E & Hadari, M 2006, ‘Economic feasibility of on-site greywater reuse in multi-storey buildings’, Desalination , vol. 190 no. 1, pp. 221-234. Web.

Hurlimann, A 2011, ‘Household use of and satisfaction with alternative water sources in Victoria Australia’, Journal of environmental management , vol. 92 no. 10, pp. 2691-2697. Web.

Hurlimann, A & McKay, J 2007, ‘Urban Australians using recycled water for domestic non-potable use—An evaluation of the attributes price, saltiness, colour and odour using conjoint analysis’, Journal of Environmental Management , vol. 83 no. 1, pp. 93-104. Web.

Jarwal, S 2006, Using recycled water in horticulture: a grower’s guide , Dept of Primary Industries, Melbourne. Web.

Kemp, B, Randle, M, Hurlimann, A & Dolnicar, S 2012, ‘Community acceptance of recycled water: can we inoculate the public against scare campaigns?’, Journal of Public Affairs , vol. 12, no.4, pp. 337-346. Web.

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.

Pelusey, M & Pelusey, J 2006, Recycled Water , Macmillan Education AU, South Yarra, Victoria. Web.

Upadhyaya, J. K & Moore, G 2012, ‘Sustainability indicators for wastewater reuse systems and their application to two small systems in rural Victoria, Australia’, Canadian Journal of Civil Engineering , vol. 39, no. 6, pp. 674-688. Web.

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Wastewater challenges - and opportunities

Wastewater is a resource that is too valuable to throw away, especially in an increasingly water-scarce world.

Wastewater from large cities is often pumped directly into rivers or seas without treatment, leading to pollution and posing a threat to the health of ecosystems and people.

But under the right conditions, wastewater can be recycled for agriculture, irrigation or industry, all of which tend to use huge quantities of the stuff.

A new report by The Nature Conservancy, Beyond the Source: The environmental, economic and community benefits of source water protection , says that for one in six of the 4,000 cities analysed, the cost of implementing source water protection activities, such as forest protection, reforestation and the use of cover crops, could be recouped through savings in annual water treatment costs alone.

This year’s World Water Day, on 22 March, looks at the sustainable management of freshwater resources with a special focus on how to deal with wastewater in African cities.

Here are some great examples of what can be done.

Greening the desert in Morocco

In Ouarzazate city in central-southern Morocco, UN Environment is helping to showcase the benefits of using treated wastewater to support reforestation.

The project, which is funded by the Korean Forest Service and the Moroccan Government and supported by UN Environment and local partners, is using municipal wastewater to irrigate degraded land for tree planting and create a greenbelt around Ouarzazate.

This greenbelt will protect the city from strong winds and dust clouds, provide a place for local people to enjoy nature, create agricultural jobs and encourage public participation in the prevention of land degradation and biodiversity loss.

It will also improve local air quality, conserve biodiversity, provide fodder, and boost the livelihoods of urban and fringe communities.

"This project has created jobs for us and opportunities to use our knowledge and experience,” says Lhoussine Chetma, an inhabitant of Ouarzazate and employee of the project.

A side-benefit of the project is that less untreated wastewater is pumped into the Monsour Eddahbi reservoir, which feeds water to the nearby NOOR solar power station. One of the biggest in the world, this power station is set to provide electricity to 2 million households.

Wastewater problems in Dar es Salaam

In the Tanzanian capital, Dar es Salaam, UN Environment, UN-Habitat, BORDA-Africa and other partners have recently started a project to show how decentralized wastewater projects can work in city areas with no sewerage facilities.

Less than 10 per cent of Dar es Salaam is connected to the “centralized” sewer network. As a result, some 90 per cent of the population use pit latrines or practice open defecation.

This threatens the marine environment around Dar es Salaam, which provides important benefits for local communities through small-scale, artisanal fisheries and tourism.

By reducing the discharge of domestic wastewater into marine ecosystems – including mangroves, sea-grass meadows, and coral reefs – everyone stands to benefit from this project.

How do decentralized treatment plants work?

Biogas Plants: Built into the ground using bricks, their function is to separate incoming wastewater in liquid and solid form and biologically digest organic solids, under anaerobic conditions. This system generates biogas useful for cooking, lighting and heating.

Anaerobic Baffled Reactors: These consist of a series of chambers in which the wastewater flows up-stream. Here, the suspended and dissolved solids in the pre-settled wastewater undergo anaerobic degradation. The activated sludge settles at the bottom of each chamber and the inflowing wastewater is forced through this sludge blanket where anaerobic bacteria make use of the pollutants for their metabolism. Progressive decomposition occurs in the successive chambers.

Planted Gravel Filters: These are a constructed wetland suitable for wastewater with a low percentage of suspended solids that have already been removed by pre-treatment. The main removal or treatment mechanisms are biological conversion, physical filtration and chemical absorption. The filters are made of planted filter bodies consisting of graded gravel.

For further information, please contact, Birguy Lamizana: birguy.lamizana [at] unep.org

Media enquiries, please contact the UN Environment Newsdesk: unepnewsdesk [at] unep.org

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Home — Essay Samples — Environment — Water Pollution — Water Pollution: A Global Imperative for Health and Environment

Water Pollution: a Global Imperative for Health and Environment

Categories: Pollution Water Pollution

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Published: Mar 6, 2024

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Waste Water Story

What is Waste Water?

It is a type of water which is contaminated by human use like washing of clothes, industrial discharge, commercial as well as agricultural activities. As all these contaminating sources disturb the quality of water which leads to contamination of water. Contamination also depends on various sources or products such as domestic wastewater, municipal wastewater i.e sewage and industrial waste of chimanies. Wastewater mainly contains physical, chemical and biological pollutants. We can purify this contaminated water by various methods, there are so many power plants which do purification processes.

Effects of Contaminant on Quality of Water:

There are various harmful result noticed due to contamination of water, some of them are listed below:

Loss of Aquatic Organisms: Aquatic organisms are harmed due to contaminated water. As discharges and runoff of harmful contaminants like pesticides into waterways can be lethal to aquatic life, causing death of fishes, prawns, etc.

Loss of Local Invertebrate Species: As these small invertebrates are food for fishes and other aquatic organisms. Death of these invertebrates lead to starvation for those aquatic organisms who are dependent on them for food and they start migrating to other water bodies exposing them to greater risk and stress.

Decrease in Biochemical Oxygen Demand(BOD): Due to waste or harmful contaminants they use up natural oxygen present in the water body. Excess nutrients can also lead to algal blooms and oxygen is used up when the algae die and decompose. Decrease in available oxygen causes difficulty in breathing to aquatic organisms.

Contaminant increases turbidity and decreases water clarity of water thus making water murky. So this aquatic organism is not able to find their prey and detect predators.

Contaminated water causes internal damage to aquatic organisms as they reduce the reproductive ability of aquatic organisms, decrease in immunity, causes disorder in the central nervous system, etc.

Types of Water Pollution Depending on Different Source:

Surface Water Pollution: This type of pollution includes pollution in rivers, lakes and oceans. Here water sources are contaminated by various means like industrial waste, release of sewage waste, etc.

Marine Pollution: one of the common ways by which contaminants enter the sea are rivers. Here directly discharging sewage and industrial waste into the ocean causes pollution into oceans. Plastic debris can absorb toxic chemicals from ocean pollution, potentially poisoning any creature that eats it.

Groundwater Pollution: Use of pesticides and insecticides causes contamination of groundwater. Groundwater pollution is directly connected to soil pollution.

Wastewater Management:

Wastewater treatment is a several step process and by going through these process we purify contaminant water:

Steps performed during purification of contaminated water:

Wastewater Collection

Primary Treatment

Secondary Treatment

Final Treatment

Wastewater Collection:

Very first step in the purification process is collection of water in a storing tank which further goes through various filtration steps.

This is the very first step of water treatment. In this process large objects are removed from wastewater and then moved into the grit and sand removal tank, where they are further treated.

Primary Treatment:

After going through screening water is taken to primary treatment where all organic waste present in water is removed and this process is done by pouring the wastewater into a big tank where solid matthew style down at the base.

The settled solids, after primary treatment, are called the sludge. This sludge is decomposed by bacteria and the gas emitted by this decomposition is known as biogas, which can be used as a fuel or can be used to generate electricity.

Secondary Treatment:

After primary treatment water is passed to an aeration tank where air is tapped into water to increase the growth of aerobic bacteria in the water. These bacteria break down small particles of sludge that are not broken during primary treatment. These broken slugs are known as activated sludge. These activated sludge contain air in them.

Final Treatment:

This activated sludge is passed through a bed of sand drying machine where the sludge is dried up and from the water is filtered out. This water is filtered and then released into the river.

How to Control Water Pollution:

There are several way to prevent water pollution, some of them are below:

Industrial Wastewater Treatment:

As industrial waste is discharged into water bodies which causes contamination of water.

So by using pre-treatment plants for reducing harmful chemicals present in industrial waste, this process will decrease contamination of water.

Agriculture Wastewater Treatment:

By reducing use of pesticides and weedicides we can reduce underground water pollution. As these chemicals contaminantes water which causes various health related issues.

Municipal Wastewater Treatment:

Instead of discharging sewage waste directly into water bodies treat it in separate sewage treatment plants to reduce water pollution.

FAQs on Waste Water Story

1. Discuss Harmful Effects of Contaminants on Quality of Water?

Ans: These harmful contaminants reduce quality of water in various ways:

2. Explain Various Steps Should be Taken for Treatment of Polluted Water.

Ans: Some major steps towards treatment of wastewater are:

As industrial waste is discharged into water bodies which causes contamination of water.

Agriculture Wastewater Treatment:

5 Ways We Waste Water

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 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 on Water Pollution for Students and Children

500+ words essay on water pollution.

Water is the most important resource for survival on a planet. It is the essence of life on our planet – Earth. Yet if you ever see a river or lake around your city, it would be evident to you that we are facing a very serious problem of Water pollution. Let us educate ourselves about water and water pollution . Two-thirds of the Earth’s surface is covered by water , seventy-six perfect of your body is made up of water.

Water and Water Cycle

As you already know water is everywhere and all around. However, we have a fixed amount of water on earth. It just changes its states and goes through a cyclic order, known as the Water Cycle. The water cycle is a natural process that is continuous in nature. It is the pattern in which the water from oceans, seas, lakes, etc gets evaporated and turns to vapor. After which it goes through the process of condensation, and finally precipitation when it falls back to earth as rain or snow.

What is Water Pollution?

Water pollution is the contamination of water bodies (like oceans, seas, lakes, rivers, aquifers, and groundwater) usually caused due to human activities. Water pollution is any change, minor or major in the physical, chemical or biological properties of water that eventually leads to a detrimental consequence of any living organism . Drinking water, called Potable Water, is considered safe enough for human and animal consumption.

Sources of Water Pollution

Domestic Waste
Industrial effluents
Insecticides and pesticides
Detergents and Fertilizers

Some of the water pollutions are caused by direct Sources, such as factories, waste management facilities, refineries, etc, that directly releases waste and dangerous by-products into the nearest water source without treating them. Indirect sources include pollutants that infuse in the water bodies via groundwater or soil or via the atmosphere through acidic rain.

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

Effects of Pollution of Water

The effects of Water Pollution are:

Diseases: In humans, drinking or consuming polluted water in any way has many disastrous effects on our health. It causes typhoid, cholera, hepatitis and various other diseases.

Eradication of Ecosystem: Ecosystem is extremely dynamic and responds to even small changes in the environment. Increasing water pollution can cause an entire ecosystem to collapse if left unchecked.

Eutrophication: Chemicals accumulation and infusion in a water body, encourages the growth of algae. The algae form a layer on top of the pond or lake. Bacteria feed on this algae and this event decreases the amount of oxygen in the water body, severely affecting the aquatic life there

Effects of the food chain: Turmoil in food chain happens when the aquatic animals (fish, prawns, seahorse, etc) consume the toxins and pollutants in the water, and then the humans consume them.

Prevention of Water Pollution

The best way to prevent large-scale water pollution is to try and reduce its harmful effects. There are numerous small changes we can make to protect ourselves from a future where water is scarce.

Conserve Water: Conserving water should be our first aim. Water wastage is a major problem globally and we are only now waking up to the issue. Simple small changes made domestically will make a huge difference.

Treatment of sewage: Treating waste products before disposing of it in water bodies helps reduce water pollution on a large scale. Agriculture or other industries can reuse this wastewater by reducing its toxic contents.

Use of environment-friendly products: By using soluble products that do not go on to become pollutants, we can reduce the amount of water pollution caused by a household.

Life is ultimately about choices and so is water pollution. We cannot live with sewage-strewn beaches, contaminated rivers , and fish that are poisonous to drink and eat. To avoid these scenarios, we can work together to keep the environment clean so the water bodies, plants, animals, and people who depend on it remain healthy. We can take individual or teamed action to help reduce water pollution. As an example, by using environmentally friendly detergents, not pouring oil down the drains, reducing the usage of pesticides, and so on. We can take community action too to keep our rivers and seas cleaner. And we can take action as countries and continents to pass laws against water pollution. Working together, we can make water pollution less of a problem—and the world a better place.

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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.

An overview of the environmental pollution and health effects associated with waste landfilling and open dumping

Municipal solid waste management and landfilling technologies: a review

Drinking water contamination and treatment techniques.

Avoid common mistakes on your manuscript.

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 .

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 .

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.

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.

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 )

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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Acknowledgements

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

Pradeep Kumar

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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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Sampling and analysis of microplastics in the coastal environments of sri lanka: estuaries of the kelani river to mahaoya.

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Click here to enlarge figure

Study Area	Matrix	Abundance (Values Refer to the Same Units)	Abundance (Original Values)	Reference
western coastline of Sri Lanka; estuaries of the Kelani River to Mahaoya	Water	-	2.0 ± 0.6 items/L to 161.0 ± 15.7 items/L	Present study
	Sediment	-	3.0 ± 0.3 items/m to 656.0 ± 34.5 items/m	Present study
22 beaches along the coastline of Sri Lanka	Sediment	-	4.1 large (>25 mm) and 158 small (5–25 mm) MPs/m	[ ]
southern coastal region of Sri Lanka	Water	0.0175 ± 0.0034 items/L	17.5 ± 3.4 items/m	[ ]
coral reef ecosystems in the eastern coastal region of Sri Lanka	Water	0.0119 ± 0.002 items/L	11.9 ± 2.0 items/m	[ ]
	Sediment	NA	42.2 ± 5.9 items/kg	[ ]
Bay of Bengal coastal stretch of Tamil Nadu, South India	Water	0.06–0.82 items/L	60–820 items/m	[ ]
Bay of Bengal coastal stretch of Tamil Nadu, South India	Sediment	NA	60–1620 items/kg	[ ]
Tanzanian coastline in East Africa	Sediment	NA	2972 ± 238 particles/kg dry sediment	[ ]
Chukchi Sea, the Bering Sea, and the Northwest Pacific	Water	1.3 × 10 ± 0.00011 items/L	0.13 ± 0.11 items/m	[ ]
Mid-west Pacific Ocean	Sediment	0.03 ± 0.03 items/m	34,039 ± 25,101 pieces/km	[ ]
Northwestern Pacific Ocean	Sediment	0.01 items/m	1.0 × 10 items/km	[ ]
South China Sea	Water	0.42 × 10 ± 0.000025 items/L	4.2 ± 2.5 items/100 m	[ ]
East Indian Ocean	Water	4.0 × 10 ± 0.000006 items/L	0.4 ± 0.6 items/100 m	[ ]

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Weerasekara, P.G.Y.W.; De Silva, D.S.M.; De Silva, R.C.L.; Amarathunga, A.A.D.; Bakir, A.; McGoran, A.R.; Sivyer, D.B.; Reeve, C. Sampling and Analysis of Microplastics in the Coastal Environments of Sri Lanka: Estuaries of the Kelani River to Mahaoya. Water 2024 , 16 , 1932. https://doi.org/10.3390/w16131932

Weerasekara PGYW, De Silva DSM, De Silva RCL, Amarathunga AAD, Bakir A, McGoran AR, Sivyer DB, Reeve C. Sampling and Analysis of Microplastics in the Coastal Environments of Sri Lanka: Estuaries of the Kelani River to Mahaoya. Water . 2024; 16(13):1932. https://doi.org/10.3390/w16131932

Weerasekara, P. G. Y. W., D. S. M. De Silva, R. C. L. De Silva, A. A. D. Amarathunga, A. Bakir, A. R. McGoran, D. B. Sivyer, and C. Reeve. 2024. "Sampling and Analysis of Microplastics in the Coastal Environments of Sri Lanka: Estuaries of the Kelani River to Mahaoya" Water 16, no. 13: 1932. https://doi.org/10.3390/w16131932

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Is Xenophobia on Chinese Social Media Teaching Real-World Hate?

Violent attacks on foreigners have prompted a debate about extreme nationalism online in a country that heavily censors information the government bans.

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July 4, 2024

The video posted last year on Chinese social media showed more than 100 Japanese children, supposedly at an elementary school in Shanghai, gathered in their schoolyard. Chinese subtitles quoted two students leading the group as screaming: “Shanghai is ours. Soon the whole China will be ours, too.”

The messages were alarming and infuriating in China, which Japan invaded during World War II. Except that the scene actually took place at an elementary school in Japan. And the students were not stoking hatred of China; they were swearing an oath to play fair at what looked like a sporting event.

The video wasn’t taken down until after it had been viewed more than 10 million times.

Xenophobic online content like the schoolyard video is the subject of debate in China right now. Last week, a Chinese man stabbed a Japanese mother and her son in eastern China. Two weeks earlier, four visiting instructors from a college in Iowa were stabbed in northeastern China. Some Chinese are questioning the role that online speech plays in inciting real-world violence.

China has the world’s most sophisticated system to censor the internet when it wants to. The government sets strict rules about what can and cannot be said about politics, economics, society and the country’s leadership. Internet companies deploy an army of censors. Private citizens censor themselves, knowing that what they post can get their social media accounts deleted or, worse, land them in jail.

Yet the Chinese internet is laden with hate speech toward Japanese, Americans, Jews and Africans, as well as Chinese who are critical of the government. False information about Japan and the United States regularly tops lists of popular searches and receives a ton of reposts and likes.

What is happening online is influenced by the rising nationalism that has been promoted in China under the leadership of President Xi Jinping. Mr. Xi has adopted a China-versus-the-rest-of-the-world mentality. One of China’s responses to worsening tensions with its rivals was “wolf warrior” diplomacy, a term used to describe an ultranationalistic and often hostile approach to geopolitics.

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News Wrap: Thousands in northern Ukraine lose power after Russian drone attack

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In our news wrap Saturday, Iran has a new president-elect after a runoff vote, Russian drone attacks hit a vital energy facility in northern Ukraine, Hamas dropped a key demand in cease-fire negotiations with Israel, Trump is distancing himself from Project 2025, and coronavirus cases in the U.S. are ticking back up after a springtime lull.

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Lisa Desjardins:

Iran has a new president elect after a runoff between a reformist candidate and a well-known hardliner. The reform minded Masoud Pezeshkian won by nearly 10 percentage points in an election that saw record low turnout during the first round of voting. Although his win has brought hope to some Iranians. Others remain skeptical of the president elects ability to change underlying problems.

Woman (through translator):

Our life is getting worse every day. It is true the salaries increase a bit but at the same time, living expenses have increased.

Among his promises Pezeshkian bow to reach out to the West and ease restrictions on the country's headscarf mandate for women. We'll discuss what the election means for Iran's future later in the program.

In Northern Ukraine, Russian drone attacks hit a vital energy facility overnight, cutting off thousands of homes from power and water. Crews are working to repair the damage and restore power, according to Ukrainian officials. The drone attacks are part of Russia's strategy to target key infrastructure.

Some new hope for a possible ceasefire in Gaza. The Associated Press reports that Hamas has initially signed off on a U.S. backed ceasefire and has dropped its demand that Israel pledged to end the war. That's been a key sticking point in negotiations.

The announcement comes as the Gaza Health Ministry announced an airstrike killed 16 people and wounded dozens more at a refugee camp. Israel says it found terrorists in the area and tried to avoid civilians.

After a springtime low, Coronavirus cases in the U.S. are taking up. New data from the Centers for Disease Control show COVID is on the rise, especially in the West. Nationwide there's been a 23 percent. jump in ER visits. The CDC says it is able to predict spikes in cases due to wastewater testing.

Still to come on PBS News Weekend, a look at Iran's future as they elect their next president and former astronaut Cady Coleman on the joys and challenges of life in space.

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What it means for the Supreme Court to throw out Chevron decision, undercutting federal regulators

FILE- Gulls follow a commercial fishing boat as crewmen haul in their catch in the Gulf of Maine, in this Jan. 17, 2012 file photo. TExecutive branch agencies will likely have more difficulty regulating the environment, public health, workplace safety and other issues under a far-reaching decision by the Supreme Court. The court’s 6-3 ruling on Friday overturned a 1984 decision colloquially known as Chevron that has instructed lower courts to defer to federal agencies when laws passed by Congress are not crystal clear. (AP Photo/Robert F. Bukaty, File)

The Supreme Court building is seen on Friday, June 28, 2024, in Washington. (AP Photo/Mark Schiefelbein)

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WASHINGTON (AP) — Executive branch agencies will likely have more difficulty regulating the environment, public health, workplace safety and other issues under a far-reaching decision by the Supreme Court .

The court’s 6-3 ruling on Friday overturned a 1984 decision colloquially known as Chevron that has instructed lower courts to defer to federal agencies when laws passed by Congress are not crystal clear.

The 40-year-old decision has been the basis for upholding thousands of regulations by dozens of federal agencies, but has long been a target of conservatives and business groups who argue that it grants too much power to the executive branch, or what some critics call the administrative state.

The Biden administration has defended the law, warning that overturning so-called Chevron deference would be destabilizing and could bring a “convulsive shock” to the nation’s legal system.

Chief Justice John Roberts, writing for the court, said federal judges “must exercise their independent judgment in deciding whether an agency has acted within its statutory authority.”

The ruling does not call into question prior cases that relied on the Chevron doctrine, Roberts wrote.

Here is a look at the court’s decision and the implications for government regulations going forward.

What is the Chevron decision?

Atlantic herring fishermen sued over federal rules requiring them to pay for independent observers to monitor their catch. The fishermen argued that the 1976 Magnuson-Stevens Fishery Conservation and Management Act did not authorize officials to create industry-funded monitoring requirements and that the National Marine Fisheries Service failed to follow proper rulemaking procedure.

In two related cases, the fishermen asked the court to overturn the 40-year-old Chevron doctrine, which stems from a unanimous Supreme Court case involving the energy giant in a dispute over the Clean Air Act. That ruling said judges should defer to the executive branch when laws passed by Congress are ambiguous.

In that case, the court upheld an action by the Environmental Protection Agency under then-President Ronald Reagan.

In the decades following the ruling, Chevron has been a bedrock of modern administrative law, requiring judges to defer to agencies’ reasonable interpretations of congressional statutes.

But the current high court, with a 6-3 conservative majority has been increasingly skeptical of the powers of federal agencies. Justices Brett Kavanaugh, Clarence Thomas, Samuel Alito and Neil Gorsuch have questioned the Chevron decision. Ironically, it was Gorsuch’s mother, former EPA Administrator Anne Gorsuch, who made the decision that the Supreme Court upheld in 1984.

What’s at stake?

With a closely divided Congress, presidential administrations have increasingly turned to federal regulation to implement policy changes. Federal rules impact virtually every aspect of everyday life, from the food we eat and the cars we drive to the air we breathe and homes we live in.

President Joe Biden’s administration, for example, has issued a host of new regulations on the environment and other priorities, including restrictions on emissions from power plants and vehicle tailpipes , and rules on student loan forgiveness , overtime pay and affordable housing.

Those actions and others could be opened up to legal challenges if judges are allowed to discount or disregard the expertise of the executive-branch agencies that put them into place.

With billions of dollars potentially at stake, groups representing the gun industry and other businesses such as tobacco, agriculture, timber and homebuilding, were among those pressing the justices to overturn the Chevron doctrine and weaken government regulation.

The U.S. Chamber of Commerce filed an amicus brief last year on behalf of business groups arguing that modern application of Chevron has “fostered aggrandizement’’ of the executive branch at the expense of Congress and the courts.

David Doniger, a lawyer and longtime Natural Resources Defense Council official who argued the original Chevron case in 1984, said he feared that a ruling to overturn the doctrine could “free judges to be radical activists” who could “effectively rewrite our laws and block the protections they are supposed to provide.”

“The net effect will be to weaken our government’s ability to meet the real problems the world is throwing at us — big things like COVID and climate change,″ Doniger said.

More than just fish

“This case was never just about fish,’' said Meredith Moore of the environmental group Ocean Conservancy. Instead, businesses and other interest groups used the herring fishery “to attack the foundations of the public agencies that serve the American public and conserve our natural resources,’' she said.

The court ruling will likely open the floodgates to litigation that could erode critical protections for people and the environment, Moore and other advocates said.

“For more than 30 years, fishery observers have successfully helped ensure that our oceans are responsibly managed so that fishing can continue in the future,’' said Dustin Cranor of Oceana, another conservation group.

He called the case “just the latest example of the far right trying to undermine the federal government’s ability to protect our oceans, waters, public lands, clean air and health.’'

West Virginia Attorney General Patrick Morrisey called the decision a fitting follow-up to a 2022 decision — in a case he brought — that limits the EPA’s ability to control greenhouse gas emissions from power plants. The court held that Congress must speak with specificity when it wants to give an agency authority to regulate on an issue of major national significance.

Morrisey, now the GOP nominee for governor, called Chevron “a misguided doctrine under which courts defer to legally dubious interpretations of statutes put out by federal administrative agencies.”

A shift toward judicial power

The Supreme Court ruling will almost certainly shift power away from the executive branch and Congress and toward courts, said Craig Green, a professor at Temple University’s Beasley School of Law.

“Federal judges will now have the first and final word about what statutes mean,″ he said. “That’s a big shift in power.″

In what some observers see as a historic irony, many conservatives who now attack Chevron once celebrated it. The late Supreme Court Justice Antonin Scalia was among those who hailed the original ruling as a way to rein in liberal laws.

“Conservatives believed in this rule until they didn’t,’' Green said in an interview.

In recent years, conservatives have focused on “deconstruction of the administrative state,’' even if the result lessens the ability of a conservative president to impose his beliefs on government agencies.

“If you weaken the federal government, you get less government,’' Green said — an outcome that many conservatives, including those who back former President Donald Trump, welcome.

The ruling will likely “gum up the works for federal agencies and make it even harder for them to address big problems. Which is precisely what the critics of Chevron want,” said Jody Freeman, director of the environmental and energy law program at Harvard Law School.

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