waste water treatment plant in hindi essay

दूषित जल उपचार संयंत्र (Waste Water-Treatment plant in Hindi)

1. प्राथमिक उपचार :-

2. द्वितीय उपचार

1. आॅक्सी उपचार

2. अनाॅक्सी उपचार, 3. तृतीयक उपचार.

• Civil Engineering
• Construction
• Laboratory test of cement
• Irrigation Enggineering

वॉटर ट्रीटमेंट प्लांट कैसे काम करता है | Water Treatment Process

• November 17, 2021 November 17, 2021
• by Sanjay Singh

आज के इस आर्टिकल में हम वॉटर ट्रीटमेंट से जुड़ी हुई बातों को जानेंगे की गंदे पानी को किस तरह water treatment plant के द्वारा साफ किया जाता है वाटर ट्रीटमेंट के सभी घटकों का क्या काम होता है। और भी बहुत कुछ तो कृपया इस आर्टिकल को पूरा पढ़ें और अच्छा लगे तो कमेंट करके फीडबैक जरूर दें।

वाटर ट्रीटमेंट प्लांट की कार्यप्रणाली को जानने से पहले हम यह समझते हैं कि पानी की ट्रीटमेंट करने की जरूरत क्यों पड़ती है क्यों नदियों तालाब में रहा हुआ पानी पीने लायक नहीं रहा तो चलिए शुरू करते हैं।

Table of Contents

पानी उपचार के हेतु | Objects of Water Treatment

कुदरत की तरफ से मिल रहा पानी जैसे कि जमीन में रहा पानी, नदी में बह रहा पानी, तालाब, झील वगेरे में रहे पानी को रो वाटर (raw water) कहते हैं।

इस पानी में विभिन्न प्रकार की अशुद्धियां होती है जैसे कि सस्पेंडेड मैटर, colloidal impurities (कलिल पदार्थ) अथवा तो डिसोल्वेड इम्प्यूरिटी रहती है।

इस प्रकार के अशुद्धियों को दूर करके पानी को योग्य गुणवत्ता प्राप्त करने की रीत को वॉटर ट्रीटमेंट कहते हैं।

पानी को शुद्ध करने का अथवा तो वॉटर ट्रीटमेंट प्लांट के मुख्य उद्देश्यों को हमने नीचे योग्य लिस्ट में बताए हैं।

• पानी में तैर रहे कचरे वगैरह को दूर करना।
• पानी में रहे हानिकारक पदार्थों तथा जहरीले पदार्थों वगैरह को दूर करना।
• पानी में से गंध तथा खराब स्वाद को दूर करना।
• पानी में से खुली हुई हानिकारक गैस को दूर करना।
• पानी में से बैक्टीरिया, जीवाणु, वायरस वगैरह को दूर करना।
• पानी को घर तथा इंडस्ट्रीज में उपयोग किया जा सके ऐसा बनाना।

चलिए जानते हैं वाटर ट्रीटमेंट प्लांट के विभिन्न भागों के बारे में।

Also Read: टाइल्स स्टीकर्स क्या होता है। कैसे लगाते हैं। फायदे और नुकसान।

वॉटर ट्रीटमेंट प्लांट के भाग | Components of Water treatment plant

वॉटर ट्रीटमेंट प्लांट के विभिन्न प्रकार के भागों को नीचे बताया गया है।

• Screening (स्क्रीनिंग)
• Plain Sedimentation (प्लेन सेडीमेंटेशन)
• Aeration (एरेशन)
• Sedimentation with Coagulation (सेडीमेंटेशन विथ कोएगुलेशन)
• Filtration (फिल्ट्रेशन)
• Disinfection (डिसिनफेक्शन)
• Softening (सॉफ्टनिंग)

1. Screening (स्क्रीनिंग)

नदी, तालाब, झील वगैरा के पानी को सबसे पहले स्क्रीनिंग किया जाता है जिसमें पानी में तैर रहे पदार्थ जैसे कि प्लास्टिक बोतल, पेड़ पौधे के भाग, जानवरों के मृत्युदेह, मछलियां वगैरह को दूर किया जाता है।

स्क्रीनिंग यह वॉटर ट्रीटमेंट प्लांट की सबसे पहली प्रक्रिया है जिसमें दो प्रकार की स्क्रीनिंग होती है।

सबसे पहले बार स्क्रीनिंग होती है जिसमें स्टील के पाइप को वर्टिकली 2.5cm के अंतर पर फिट किया होता है। और एक जाली बनाई जाती है जिसमें नदी अथवा तो ताला वगैरह के पानी में बह रहे बड़े-बड़े कचरे फर्स्ट फस जाते हैं। इसे साफ करने के लिए मैकेनिकल क्लीनिंग डिवाइस का उपयोग किया जाता है जो इसी में फिट रहता है कंटीन्यूअसली कचरो को साफ करके साइड के drain में डाल देता है।

पानी को बाहर स्क्रीनिंग में से गुजरने के बाद फाइल स्क्रीनिंग में से गुजारा जाता है जिसमें 6mm साइज की जाली होती है इसमें पानी में रहे सूक्ष्म पदार्थ को दूर किया जात है।

Also Read: घर के सुंदर exterior view के लिए सही पेंट कलर कैसे पसंद करें?

2. Plain Sedimentation (प्लेन सेडीमेंटेशन)

पानी को स्क्रीनिंग करने के बाद पानी को प्लेन सेडिमेंटेशन टैंक में लाया जाता है जिसमें उसे काफी समय तक स्थिर रहने दे जाता है।

प्लेन सेडिमेंटेशन प्रक्रिया में पानी को टैंक में स्थिर होने दिया जाता है जिससे पानी में रहे ज्यादा घंटा वाले पदार्थ ताकि के तल पर बैठ जाते हैं और पानी साफ दिखने लगता है।

3 . Aeration (एरेशन)

अरेशन यह एक प्रकार से पानी को नेचुरल साफ होने वाली प्रक्रिया जैसे ही है।

नदी में बह रहा पानी खुले मैदान में बहने के कारण हवा में रही ऑक्सीजन को एक जॉब करता है तथा खुद में रही बिलिंग गैस जैसे कि कार्बन डाई ऑक्साइड, सल्फर ऑक्साइड वगैरह रिलीज करता है इस प्रक्रिया को सेल्फ क्लीनिंग ऑफ वाटर कहते हैं।

अरेशन भी एक प्रकार से यही प्रक्रिया है जिसमें पानी को खुली हवा में ग्रेविटी अरेटर ( सीढ़ी की तरह बनाया गया स्ट्रक्चर) के ऊपर बहाकर हवा में रहे ऑक्सीजन को शोषित किया जाता है जिससे पानी में रहे अन्य गैसेस दूर हो जाते हैं।

4. Sedimentation with Coagulation (सेडीमेंटेशन विथ कोएगुलेशन)

प्लेन सेडिमेंटेशन में पानी में रही विलीन अशुद्धिया, कलिल अशुद्धियां, सूक्ष्म कण वगैरह दूर नहीं होते हैं।

एक रिसर्च से ऐसा पता चलता है कि सूक्ष्म कण जैसे कि 0.06mm साइज के कांप के कण को एक ही हाइट की टंकी के तल में बैठने में जितना समय लगता है उससे 10 गुना ज्यादा समय 0.02mm साइज के कांप के कण को लगता है टंकी के तल में नीचे बैठने में।

इससे यह पता चलता है कि पानी में रही सूक्ष्म अशुद्धियां को दूर करने में बहुत समय की जरूरत पड़ती है साथ ही साथ ज्यादा पानी को संग्रह करने के लिए ज्यादा जगह की भी जरूरत पड़ती है जो कि ज्यादातर संभव नहीं रहती है।

इसलिए पानी में रही सुक्ष्म कण तथा अन्य अशुद्धियों को दूर करने के लिए पानी में रसायन (chemical) डालने में आता है। फिर उसे पानी के साथ बराबर मिलाया जाता है जिससे पानी में रही सूक्ष्म कण रसायन के कणों के साथ इकट्ठे हो जाते हैं मतलब जुड़कर बड़े कण में रूपांतर हो जाते हैं। साथ ही साथ एकत्रित होते समय अन्य अशुद्धियां जैसे कि कालिल अशुद्धियां को भी अपने साथ ले लेते हैं फिर बाद में यह अशुद्धिया धीरे-धीरे टंकी के तल पर बैठ जाती है जिससे पानी जल्द साफ हो जाता है।

इस प्रक्रिया को coagulati प्रक्रिया कहते हैं तथा जो chemical उपयोग किए जाते हैं उसे कोएगुलेंट कहते हैं।

Also Read: ईंट कैसी होनी चाहिए।

5. Filtration (फिल्ट्रेशन)

फिल्ट्रेशन प्रक्रिया में पानी में बच गई सुक्ष्म कण, वायरस, बैक्टीरिया, स्वाद, गंध वगैरह को दूर किया जाता है।

6. Disinfection (डिसइनफेक्शन)

डिसइन्फेक्शन में पानी में रही हुई पथोजेनिक बैक्टीरिया, जर्म्स, माइक्रो ऑर्गेनिजमस, वगैरह को दूर करने में आता है इस प्रक्रिया में पानी में क्लोरीन ऐड किया जाता है जो पानी को लंबे समय तक फ्रेश बनाए रखता है और उसे पीने लायक भी बनाता है।

7. Softening (सॉफ्टनिंग)

पानी में कैल्शियम तथा मैग्नीशियम कार्बोनेट, क्लोराइड्स, सल्फेट वगैरह खुलने के कारण पानी कठोर हो जाता है। पानी के कठोर हो जाने के कारण रसोई स्वादहीन बनती है, कपड़े धोने में साबुन का ज्यादा खर्च होता है, पाइप फिटिंग्स, वाल्व, नल वगैरे पर सफेद पाउडर की परत जम जाने के कारण वह सभी ब्लॉक हो जाते हैं तथा पानी की कठोरता के कारण धातु पर जंग लगता है।

softening प्रोसेस में पानी की कठोरता को दूर किया जाता है।

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Use technology, recycle water! (Hindi)

This poster depicts the problem of improper wastewater management, including water pollution and waterlogging. It proposes the solution of water conservation and wastewater treatment and reuse.

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Status of water treatment plants in India - A report on their operational status by the Central Pollution Control Board

This document   by the Central Pollution and Control Board (CPCB) describes the findings of a study that evaluated water treatment plants located across the country, for prevailing raw water quality, water treatment technologies, operational practices, chemical consumption and rejects management.

The report is subdivided into the following chapters:

• Introduction
• Water quality and its consumption
• Water treatment technologies
• Effects of fluoride and arsenic and removal techniques
• Operation and maintainance of water treatment plants
• Water quality control and assessment
• Results and discussion

The aims of this project were as follows:

• To study the water treatment plants for their operational status
• To explore the best feasible mechanism to ensure proper drinking water production with least possible rejects and its management.

The methodology consisted of three phases: 

• Questionnaire survey covering 202 class 1 towns
• Field studies (dry and wet studies)in 52 water treatment plants throughout the country including sample collection and analyses in 30 plants, and 
• Compilation of information

The study found that:

• Surface water is the predominant source of raw water for all water treatment plants
• Conventional treatment is provided having a sequence of alum addition, coagulation, flocculation, sedimentation, filtration and disinfection by chlorination
• The study revealed that there is no uniform or set pattern of operation and maintenance of water treatment plants
• Alum was being added as coagulant in almost all the water treatment plants
• Alum dosing equipments were found to be not working in many water treatment plants. 
• Algae growth was not significant in case of rapid sand filters. However, in case of open filters having direct sunlight, frequent cleaning of filter bed walls to remove algae is required
• Study reveals that filter backwash water and clarifier sludge of water treatment plants need to be treated before discharge
• Central Pollution Control Board developed technology for recovery and reuse of the alum used for clarification, which is under execution for viability of pilot scale.

The study suggested that:

• Sludge and filter back wash water needed to be treated and properly disposed
• Almost all the water treatment plants were using liquid chlorine for pre & post chlorination, except few, which were using bleaching powder. Use of pre chlorination could be avoided due to possibility of formation of Tri halo methane. Use of ozone, copper sulphate, potassium permanganate etc. could be explored thorough R & D activity wherever algae problem was faced or contamination of water source was suspected
• In many cases, chlorination was not found functioning at the time of visit resulting in excessive use of chlorine. This caused chlorine leakage and corrosion of water treatment plant equipment and structure, therefore, a mechanism, similar to that of the boiler inspectors was to be established to ensure proper functioning of chlorinators
• Water treatment plant operators needed regular training. Proper database of operation & maintenance of water treatment plant neede to be prepared and efficient Management Information Systems (MIS) had to be developed to cater to all the activities of water treatment plants.

A copy of the report can be downloaded from below:

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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:

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.

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:  

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• Open access
• Published: 30 April 2020

Contributions of recycled wastewater to clean water and sanitation Sustainable Development Goals

• Cecilia Tortajada 1  

npj Clean Water volume  3 , Article number:  22 ( 2020 ) Cite this article

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• Social policy
• Water resources

Water resources are essential for every development activity, not only in terms of available quantity but also in terms of quality. Population growth and urbanisation are increasing the number of users and uses of water, making water resources scarcer and more polluted. Changes in rainfall patterns threaten to worsen these effects in many areas. Water scarcity, due to physical lack or pollution, has become one of the most pressing issues globally, a matter of human, economic and environmental insecurity. Wastewater, whose value had not been appreciated until recently, is increasingly recognised as a potential ‘new’ source of clean water for potable and non-potable uses, resulting in social, environmental and economic benefits. This paper discusses the potential of recycled wastewater (also known as reused water) to become a significant source of safe water for drinking purposes and improved sanitation in support of the Sustainable Development Goals.

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Introduction

The Sustainable Development Goals (SDGs) are the most recent attempt by the international community to mobilise government, private and non-governmental actors at national, regional and local levels to improve the quality of life of billions of people in the developed and developing worlds. The goals are an ambitious, challenging and much-needed action plan for “people, planet and prosperity” until the year 2030 1 .

Of the 17 SDGs, the sixth goal is to “ensure availability and sustainable management of water and sanitation for all”. The achievement of this goal, even if partially, would greatly benefit humankind, given the importance of clean water for overall socio-economic development and quality of life, including health and environmental protection.

In 2000, the Millennium Development Goals (MDGs) aimed at reducing by half the proportion of the population without sustainable access to safe drinking water and sanitation by 2015. This objective, however, did not take into consideration water quality or wastewater management aspects, which represented a main limitation for its achievement 2 . This omission has been rectified in the Sustainable Development Goals (SDGs), where one of the goals (SDG 6) calls for clean water and sanitation for all people by ensuring “availability and sustainable management of water and sanitation for all”. Among other aspects, it considers improvement of water quality by reducing by half the amount of wastewater that is not treated, and increasing recycling and safe reuse globally. This will result in the availability of more clean water for all uses, and on an enormous progress on sanitation and wastewater management. This target unequivocally indicates the close interrelation between clean water, sanitation and wastewater management, giving these two last aspects the importance they deserve. No government of any human settlement irrespective of its size, be it a megacity, mid-size city or large or small town, can provide clean water without concurrently considering sanitation and wastewater management. Clean water is not, and will never be possible, if wastewater is not collected, treated and disposed properly for the intended uses.

Constraints for the provision of clean water and sanitation for all are complex, and depend on decisions of actors at all levels of government, private sector, non-governmental organisations and the public. They are also determined by broad development policies that may or may not prioritise provision of these services over the long-term, national and local action plans that, even when properly formulated, are often not adequately implemented due to short-term planning, lack of managerial, financial and/or man-power capacity and water needs of other sectors such as the energy or agriculture sectors on which the water sector has limited say or control. The most damaging limitation is often political will that is not sustained and that depends on political interests and electoral cycles. These aspects as well as many others that hampered the progress of the MDGs and represent serious constraints for the SDGs include discrepancy between global goals and national and local limitations, lack of continuity in decisions, policies and investments from one administration to the other, poor or inexistent data that inform decision-making or disadvantaged populations that do not have access to appropriate water and sanitation services 3 .

In most developing countries, provision of clean water and, to a certain degree, also sanitation services, are prioritised over other services. Nevertheless, this prioritisation is not always accompanied by sustained support, resources, or interest. Regarding wastewater management, this is simply left behind. There does not seem to be appreciation of the numerous negative impacts wastewater and related pollution have for provision of clean water, and how much they adversely affect human health and the environment.

It is a fact that water resources globally are under pressure from economic development, population growth, urbanisation, and more recently, climate variability and change; however, it is also pollution to a large extent what is restricting the availability of water for all people for all uses in quantity and quality. It is difficult to find a solution because, as discussed earlier, this depends on numerous technical and non-technical decisions that are taken without analysing their implications on water availability. The situations are further exacerbated by legal and regulatory frameworks that are not implementable, absence of long-term planning, inadequate management and governance, government capability, neglect of demand-side practices (pricing and non-pricing measures), disregard of awareness building including attitudes and behaviour, and poor intersectoral collaboration. Adequate consideration of these aspects depends on economic, social, environmental, cultural and political contexts and institutional capabilities of the places where they are implemented. Properly pursuing SDGs in general, and SDG 6 in particular, have the potential to improve not only access to water and sanitation and quality of life of billions of people, but also contributing towards better capacities of national and local governments.

SDGs main targets of reducing by half the amount of wastewater that is not treated, and increasing recycling and safe reuse present the distinct possibility of producing ‘new’ sources of clean water for all uses that would not be available otherwise. It would further mean that wastewater discharged to water bodies would be cleaner and safer than what it is at present, and that source water for communities downstream would be of much better quality. It would further contribute to improvements in aquatic environments.

Potable water reuse is not new. However, what has made it more relevant at local and also at national levels such as in Singapore, and now potentially in United States, is growing water scarcity and pollution that is reducing water resources available for larger populations and more uses.

The rest of the paper presents the poor status of water quality globally, and discusses the distinct potential wastewater treatment and reuse have to produce new sources of clean water, as well as to improve sanitation and wastewater management, supporting the UN’s development goal of clean water and sanitation for all. This would also contribute, at least partially, to the progress of several others non-water related SDGs such as poverty alleviation, good health and well-being, and improved education and gender equality. Examples of projects that produce reused water for potable purposes are presented including their benefits, as well as the views of the local populations. Finally, challenges to implement potable water reuse more extensively are discussed.

Results and Discussion

Water pollution and impacts on human health and environment.

Worsening water pollution affects both developed and developing countries. In developing countries, it is mostly due to rapid population growth and urbanisation, increased industrial and other economic activities, and intensification and expansion of agriculture, coupled with lack of local and national legal and institutional capacities (managerial, technical, financial, enforcement, etc.) and political and public apathy to improve and maintain water and wastewater management processes in the long-term. Much attention is given to sanitation, specially to construction of toilets and wastewater treatment plants, but their construction alone will not improve water quality over medium- and long-terms unless commensurate attention is given to significantly improving institutional capacity for planning, management, and implementation 4 .

Water pollution has increased significantly in most rivers in Africa, Asia and Latin America since 1990. Pathogenic and organic pollution has worsened in more than half of river stretches, severely limiting their use. These findings are based on measurements of parameters that indicate pathogen pollution (faecal coliform bacteria), organic pollution (biochemical oxygen demand), and salinity (total dissolved solids) 5 . Although sanitation coverage and wastewater treatment have improved in some countries, they have not been enough to reduce the faecal coliform pollution reaching surface waters 6 . This does not include contamination due to industrial and agricultural wastewater which discharges contain hazardous chemicals, heavy metals, and other inorganic pollutants. Consequently, an estimated 2 billion people use drinking water sources that are contaminated, making millions sick.

According to the Global Burden of Disease studies 7 , between 1990 and 2017, the worst deterioration of water quality was in Southeast Asia, East Asia, and Oceania (86% increase in the parameters measured), North Africa and the Middle East (58% increase), and South Asia (56% increase). Parameters used to estimate unsafe water sources include proportion of individuals globally with access to different water sources (unimproved, improved except for piped supply, or piped water supply), and who have reported use of household water treatment methods such as boiling, filtering, chlorinating or solar filtering (or none of these). For unsafe sanitation, the parameters used are the proportion of individuals with access to different sanitation facilities (unimproved, improved except sewer, or sewer connection).

In developed countries, people’s access to safe sources of water and to sanitation and wastewater services has improved. However, these services still lag behind for people in poor urban, peri-urban, and rural areas, showing inequality among and within communities and regions, with the poorest people generally being in the most difficult situations 8 . Water quality has also improved in general, but pollutants have multiplied and diversified, putting pressure on governments and utilities to improve treatment processes for both drinking water and wastewater 9 .

United States, for example, acknowledges new and long-standing problems. These include a combination of point sources of pollution (such as toxic substances discharged from factories or wastewater treatment plants) and non-point sources (such as runoff from city streets and agricultural sources like farms and ranches). Another problem has been insufficient financial support for municipal wastewater treatment plants 10 . In 2009, according to data reported by the EPA (2009) 11 and the states, 44% of river and stream miles assessed, and 64% of lake acres assessed, did not meet applicable water quality standards and were not apt for one or more intended uses. In 2019, an assessment of lakes at the national level found that ~20% of them had high levels of phosphorus and nitrogen 12 . Although more work is necessary, the United States has the advantage of robust legal and institutional frameworks that have fostered progress in improving quality in drinking water and bodies of water.

Europe is not without problems. According to the European Environment Agency 13 , good chemical status has been achieved for only 38% of surface waters and 74% of groundwater in the EU member states. Surface water bodies are affected mostly by hydromorphological pressures (40%), non-point sources of pollution (38%, mostly agricultural), atmospheric deposition (38%, mainly mercury), point sources of pollution (18%) and water abstraction (7%). In England, only 14% of rivers meet the minimum good status standard; France, Germany, and Greece have been fined by the European Court of Justice for violating regulatory limits on nitrates, with almost a third of monitoring stations in Germany showing levels of nitrates exceeding EU limits.

Risks posed by emerging contaminants such as pharmaceuticals and microplastics are still poorly understood, and thus cannot be adequately incorporated in planning and management of potable water supply. Current and future research on emerging contaminants and their impacts is necessary to fully understand the best management and treatment processes.

Safe reuse for additional sources of safe water

Safe reuse of water resources (using them more than once) is a radical contribution to the old paradigm of water resources management, which seldom considered the value of recycled wastewater and its reuse for potable uses. Larger populations that require more water and produce more wastewater that is not always treated properly, current and projected water scarcity and degradation and water-related health and environmental concerns have led a growing number of cities to treat municipal wastewater to higher quality, and either reusing it for potable and non-potable purposes or discharging it (now cleaner) to the environment. Appropriate regulations, improved technology, more reliable monitoring and control systems, and considerations of public views have made it a feasible alternative to increase the amount of clean water available for potable purposes 14 .

Augmentation of water resources for potable purposes with reused water can be done either directly or indirectly. Terminology varies, but generally, in indirect potable reuse (IPR), reused water is introduced into an environmental buffer (reservoir, river, lake or aquifer) and then treated again as part of the standard supply process. In direct potable reuse (DPR), reused water is sent to a drinking water treatment plant for direct distribution without going through an environmental buffer.

Potable water reuse projects have been implemented in cities in the United States, Namibia, Australia, Belgium, United Kingdom and South Africa, as well as in Singapore 15 . The common denomination in all cases for project development has been water scarcity. All projects have prioritised public health and the environment and risk management. Because water reuse diversifies the water resources available, its value has become more evident during droughts, when surface and groundwater are more limited for all uses.

Local experiences considered successful

This section refers to potable water reuse in several cities, with emphasis on United States because of its current progress in this area.

United States has developed the largest number of water reuse projects of any country, supported by policies and regulations that promote safe reuse of water from recycled wastewater (in 2017, 14 states had policies to address indirect potable reuse and three to address direct potable reuse, compared with eight and none, respectively, in 2012). Measures have been taken to improve use and management of freshwater resources, developing water management tools and drought preparedness plans, conservation actions, addressing dependence on expensive inter-basin water transfers, assessing climate change, and revising water reuse from the knowledge, management, technological, financial, and public-opinion viewpoints.

In US, there are no specific federal regulations for potable water reuse; however, all potable water should meet federal and state water quality regulations, such as the Safe Drinking Water Act and the Clean Water Act. In parallel to these Acts, several states have developed their own regulations or guidelines governing indirect potable reuse, while direct potable reuse facilities are currently considered on a case-by-case basis. In Big Spring and Wichita Falls, Texas, direct potable reuse has been implemented as the most effective, or the only feasible way to provide clean water 16 .

California is the most progressive state regarding indirect potable water reuse, with the most developed regulatory frameworks. For more than 50 years, several cities have implemented planned replenishment of groundwater basins with reused water. Regulations were adopted in 1978 and revised in 2014. In 2018, indirect potable reuse regulations of surface water augmentation were adopted. They allow reused water to be added to surface water reservoirs that are used as sources of drinking water 17 . No project has been implemented yet but the first two (in San Diego County) are expected to be completed by 2022.

The state does not have regulations for direct potable reuse at present. However, the State Water Board is working on a Proposed Framework for Regulating Direct Potable Reuse to develop uniform water recycling criteria that will protect public health, and avoid “discontinuities” in the risk assessment/risk management approach as progressively more difficult conditions are addressed 18 .

The best-known potable reuse project in California, in the country, and internationally, is the Orange Country Groundwater Replenishment System. Indirect potable reuse has been the long-term response of the district (as has been for the state) to provide clean water for growing human and environmental needs. The system supplies potable reused water for ~850,000 people. Reused water is for recharging the groundwater basin to protect it from seawater intrusion. A final expansion project will increase the system’s treatment capacity, enabling the district to continue protecting the groundwater basin and providing clean water to its growing population 19 . The project is considered a precursor and benchmark for subsequent water reuse projects in El Paso, Texas, the West Basin Water Recycling Plant in California and the Scottsdale Water Campus in Arizona.

A recent initiative of the EPA, the National Water Reuse Action Plan, has the potential to implement water reuse at the national level. This Action Plan, announced in February 2020, has the objective to secure the country’s water future for all uses by improving security, sustainability, and resilience of water resources through water reuse and identify types of collaboration between governmental and nongovernmental organisations to make this possible. The plan also aims to address policy, programmatic issues, and science and technology gaps to better inform related regulations and policies 20 .

Reused water has also been produced in Windhoek and Singapore. Windhoek is the first example of direct potable reuse globally from 1968, as the best, and only alternative to water scarcity, exacerbated by recurrent droughts 21 . Given its importance for water security, potable reuse has been considered for decades as a strategic component of water resources management. During the very severe drought in 2015–2017, surface water (the main water source) fell to 2% of supply from the normal 75%, putting enormous pressure on the water system and on the domestic, commercial and industrial sectors. Most of the water used to replace the surface water was drawn from the local aquifer, and potable reused water increased to 30% of supply 22 . Potable water reuse additional domestic supplies and domestic water rationing was not necessary. From October 2019 and through the writing of this article in early 2020, Windhoek faced another very severe drought during which potable water reuse also represented an essential source of clean water for potable purposes, until it finally rained.

In Singapore, production of NEWater (as reused water is known) started in 2003 as part of a long-term strategy to diversify water resources and reduce Singapore’s dependence on water imported from Johor, Malaysia, with a goal of resilience and self-sufficiency by 2060. Reused water meets ~40% of Singapore’s daily water needs and will cover ~55% by 2060. During dry months, NEWater is added to the reservoirs to blend with raw water before undergoing treatment and being supplied for potable use 23 . While water reuse was not a new concept in 2003, what has been significant in this case is its large-scale implementation and the wide public acceptance of indirect potable and direct non-potable reuse due comprehensive education and communication strategies 24 . These emphasise the water-scarcity reality in the city-state and the importance of water reuse to produce the water that is needed for overall development.

In Europe, the EU recognises the importance of reducing pressures on the water environment due to water scarcity, and encourages efficient resource use. Its policy on water reuse does not include potable uses, leaving this decision to the member states; it refers only to non-potable uses, with focus on irrigation for agriculture 25 .

Within this framework, the only two projects that have been developed in the region so far are the Langford Recycling Scheme in United Kingdom and Torrelle plant in Belgium. Both produce water to be used indirectly for drinking water supplies. The Langford Recycling Scheme operates only when the flow of the River Chelmer is low, supplying up to 70% of the flow during drought periods. The highest production has been during drought periods in 2005–2006 and 2010–2011 26 . In Belgium, Torrelle plant supplies safe drinking water to nearby communities, ~60,000 people in 2012, and is also used for artificial recharge of the dune aquifer of Saint-André preventing seawater intrusion 27 .

Table 1 presents an overview of the projects mentioned above 28 . In the decades over which these projects have supplied drinking water, no negative health effects have been documented.

Local experiences where challenges remain

The most recent potable reuse projects that have been stopped are in Australia. The country has robust legal and regulatory frameworks to support potable reuse 29 , but so far only one project has been successfully implemented, in Perth, Western Australia 30 . Two potable water reuse projects in Queensland have been halted due to health concerns, poor communication and public opposition in one case (Toowoomba 31 ), and on lack of political support in the other case (Western Corridor Recycled Water Project) 32 . In both cases, decisions were taken even when there were concerns on the impacts of climate change in the region and the possibility that rainfall patterns might not be appropriate for future purposes.

Acceptance of potable water reuse requires robust regulations and advanced technology; however, it also requires serious consideration of the soft-aspects such as education, communication and engagement of politicians, decision-makers and the public, and emotional response and trust 33 . Messages should not be limited to the benefits of the projects. They should also discuss aspects such as water quality and safety, water supply alternatives and their feasibility and costs, risk management, and implications for those who will consume the water 34 .

In the developing world, cities in Brazil, Mexico, Kuwait, and India have constructed or are planning projects, for potable water reuse. Their possibilities to succeed are limited as projects would have to be implemented within regulatory, institutional, governance, management, financial and technological frameworks that are robust and promote innovation, and utilities would have to ensure technical, managerial and financial capacities in the long-term. A serious limitation is that water management in general, and collection and conventional treatment of municipal and industrial wastewater in particular, are still challenging; often water quality standards and monitoring are poorly enforced, and risk assessment frameworks are lacking. Irrespective of how important potable water reuse is for clean water and sanitation goals at local, regional and national levels, challenges remain for its extended implementation.

Knowledge gaps and research needs

Protection of human health and the environment is paramount for any source of drinking water, be it reused water or not. To ensure reused water is safe for potable purposes, it is crucial that it meets standards for pathogens and chemicals (federal, state and local), monitoring is robust, comprehensive and continuous, reporting and independent auditing are performed and knowledge gaps and research needs are addressed 35 .

Overall, types of research needed include further evaluations of common drinking water treatment processes and their inactivation and/or removal efficiency, regulated and unregulated contaminants and their expected presence in reused water, microbial, chemical, radiological and emerging contaminants, monitoring of the influents and effluents of water treatment plants and real-time monitoring of water as it passes through the treatment train. This will facilitate rapid responses, immediately identifying any changes in the water quality due to pathogens or chemical pollutants, detect their types and amounts, and decide on the most appropriate response 36 . General risks can also be reduced through wastewater source control, water source diversification and allocation of risks, so that each party can manage the different risks.

A growing area of concern is the presence of commonly used chemicals and emerging contaminants, their mixture even at low doses, and their effect in human health and ecosystems. This is particularly important if they are detected more often in advanced treated water as they can cause acute or chronic diseases. Better regulations, and improved treatment and monitoring have been identified as key to address the above issues and comply with potable water quality parameters 37 . Web-based data analytics and a system for population water reporting are also important as they will enhance data collection, and increase information accessibility.

To further understand risks of emerging contaminants, major research efforts based on toxicological and epidemiological studies have been carried out. At present, however, health and environmental protection relies in the measurement of chemical and microbiological parameters and the application of formal processes of risk assessment. The objective is that identification, quantification and use of risk information informs decision-making on social and environmental impacts and benefits, as well as on financial costs 38 . Effects on vulnerable groups like infants, elderly, pregnant women, and persons who are already ill, are less understood and thus require additional research.

In direct potable reuse, the absence of an environmental buffer means shorter failure response times, which may affect the ability of plant operators to stop operations if off-specification water is detected. In these cases, supplementary treatment, monitoring, and engineered buffers are expected to provide equivalent protection of public health and response time if water quality specifications are not met 39 .

Table 2 lists benefits and challenges related to potable water reuse. It does not intend to be exhaustive, but to indicate the most relevant issues in both cases.

Potable water reuse schemes are subject to stringent regulations. They follow risk assessment and drinking water safety plans, which include pilot studies, process control considerations, standards, monitoring and auditing of water quality, consideration of stakeholders and public perceptions and risk minimisation, among other factors. Treatment technologies used are advanced and require membrane filtration and ultraviolet disinfection to remove or destroy viruses, bacteria, chemicals, and other constituents of concern as part of the process of converting wastewater into a clean, safe source of municipal drinking water. Reused water is thus cleaner, and safer, than river flows in many cities, especially in the developing world, where improperly treated (or, more commonly, untreated) wastewater is normally discharged.

Potable water reuse and the SDG for water and sanitation

Proper treatment of wastewater and safe reuse are prerequisites if the main targets of Goal 6 are to be reached by 2030. Failure to achieve this goal will mean that health and living conditions of billions of people will suffer, as they have suffered until now, or even more, as populations are growing and water resources are scarcer and more polluted.

Wastewater that is treated and safely reused for potable purposes becomes a new source of water that can be supplied to growing populations. Examples mentioned earlier show that there are thousands of people with access to clean water due to potable water reuse. This is water that would not be available otherwise. Potable water reuse has become more relevant during drought periods when populations with access to reused water have not suffered of water rationing, while people elsewhere without this alternative have not had the same opportunity.

Potable water reuse represents a reliable alternative way to produce safe water, improve the quality of water in receiving water bodies, and mitigate water scarcity for all uses, contributing to the SDG on clean water and sanitation. More broadly, to improve overall quality of life. However, such projects alone cannot enable the achievement of SDG 6, and produce all the safe water the world is running short of at present and will need in the future. As argued earlier, water reuse is part of comprehensive water planning and management strategies.

Water scarcity needs to be approached holistically. At present and looking towards the future, when demands for safe water will be more pressing and water resources will be less available than now, all alternatives for water supply must be considered, potable water reuse included.

The study followed a three-method approach. The first was literature review and analysis to understand the range of issues that determine the extent of the contributions of water reuse towards the realisation of clean water and sanitation Sustainable Development Goals in specific, and to the progress of several other non-water related SDGs positively influencing quality of life. Following the review and analysis, the second approach was the discussion of water reuse projects that have been operational for decades and that have rendered numerous benefits to the population in terms of safe water and sanitation, as well as projects that have been halted due to health concerns and insufficient involvement of the public. Finally, the most recent initiatives to strengthen and diversity the water resources available at the national level, e.g., United States, are presented to emphasise the fundamental role of water reuse towards fulfilment of the SDGs on clean water and sanitation.

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Acknowledgements

This research was funded by the Institute of Water Policy, Lee Kuan Yew School of Public Policy, National University of Singapore. Grant R-603-000-289-490.

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Tortajada, C. Contributions of recycled wastewater to clean water and sanitation Sustainable Development Goals. npj Clean Water 3 , 22 (2020). https://doi.org/10.1038/s41545-020-0069-3

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Water Policy in Pakistan pp 323–349 Cite as

Wastewater Treatment in Pakistan: Issues, Challenges and Solutions

• Fozia Parveen 7 &
• Sher Jamal Khan 8  
• First Online: 27 September 2023

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1 Citations

Part of the book series: Global Issues in Water Policy ((GLOB,volume 30))

Currently able to treat only 1% of its wastewater, Pakistan is far from its commitment under the sustainable development goals (SDGs) to treat up to 50% of its wastewater. The rapid urbanization of cities without corresponding improvements in infrastructure to collect and treat wastewater leads to poor quality water and sanitation. The organizations responsible for wastewater treatment are also responsible for providing quality drinking water, i.e., WASA (Water and Sanitation Authorities). This has resulted in untreated wastewater being used for irrigation, and heavy contamination of ground and surface drinking water, thus leading to disease. Decentralized wastewater treatment plants and nature based systems need to be introduced to both cities and villages so that water can be reused in a healthy and sustainable way. Industries are now beginning to adhere to compliance standards while cities are becoming aware that open drains are not a long term solution to this problem. In short, Pakistan needs to consider the long-term benefits of wastewater treatment instead of its short-term costs, and make it a priority.

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Fozia Parveen

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Parveen, F., Khan, S.J. (2023). Wastewater Treatment in Pakistan: Issues, Challenges and Solutions. In: Ahmad, M. (eds) Water Policy in Pakistan. Global Issues in Water Policy, vol 30. Springer, Cham. https://doi.org/10.1007/978-3-031-36131-9_12

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• CBSE Notes For Class 7
• CBSE Class 7 Science Notes
• Chapter 18: Wastewater Story

Wastewater Story Class 7 Science Notes - Chapter 18

According to the CBSE Syllabus 2023-24, this chapter has been renumbered as Chapter 13.

• Wastewater refers to all effluent from a household, hospitals, commercial organizations and institutions, industries and so on. It is also inclusive of agricultural, horticultural, stormwater and urban runoff, and aquaculture effluent.
• Effluent is used to refer to the liquid waste or sewage that is discharged into water bodies either from treatment plants or direct sources.

Contaminants

A contaminant is something that contaminates a substance, such as water or food.

Organic Impurities

• Organic impurities may include substances that pollute abiotic components like water, soil etc. Organic impurities, which pollute water, are collectively called sewage.
• Organic impurities in sewage include animal waste, urine, oil, vegetable and fruit waste, faeces, pesticides and herbicides.

Inorganic Impurities

Inorganic impurities include phosphates, nitrates and metals. Inorganic impurities generally do not contain any carbon, but there are certain inorganic impurities which contain carbon, like carbon dioxide.

• Bacteria are a type of microorganism, which are tiny forms of life that can only be seen with a microscope.
• Harmful bacteria that cause bacterial infections and disease are called pathogenic bacteria.
• The diseases caused by bacteria are typhoid, cholera, pneumonia etc.

Sewage: Who’s That?

• Sewage is the wastewater released by hospitals, homes or industrial establishments that is carried away in sewers or drains for dumping or conversion into a form that is not toxic.
• Sewage is a liquid waste containing a complex mixture of suspended solids, organic and inorganic impurities, nutrients, saprophytic and disease-causing bacteria, and some other microbes.

To know more about Sewage, visit here .

Saprophytes

Saprophytic bacteria are the kind of bacteria that feed on dead decaying plants and animals, rotten wood, stagnant water and many other decaying substances, which are rich in organic matter.

To know more about Saprophytes, visit here .

Wastewater Management

Wastewater treatment is a process used to remove contaminants and make the water usable.

• Wastewater Collection

Primary Treatment

Secondary treatment.

• Final Treatment
• Screening is one of the first stages in the process of treating wastewater.
• In this process, the larger objects are removed from wastewater and then moved into the grit and sand removal tank.
• Wastewater after screening is taken for primary treatment, where all the organic waste is removed.
• Primary treatment is done by pouring the wastewater into big tanks for the solid matter to settle at the surface of the tanks.

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

• Water after primary treatment is passed through a tank called ‘aeration lane’’ where the air is tapped into the water to increase the growth of aerobic bacteria.
• Bacteria break down small particles of sludge that escape after primary treatment.

Activated sludge

After the secondary treatment, the broken down sludge settles down at the base of the huge tank, known as ‘activated sludge’. It contains air in it.

Final treatment

• The activated sludge is passed through a bed of sand drying machine where the sludge is dried up, and water is filtered out.
• The water is directed to flow over a wall, wherein it gets filtered through a sand bed to eliminate additional particles, if any.
• This water that is filtered is then released into the river.

Sewage Systems

Sewage systems.

Sewage from each house is collected through the drainage, and the network of pipes called sewers take them to the wastewater treatment plants, from which it’s released into water bodies.

Better Housekeeping Practices

• Cooking oil and fats should not be thrown down the drain as the fats clog and block the pipes.
• Used tea leaves, solid food remains, soft toys, cotton, sanitary towels, etc., should not be thrown in drains as they do not allow the free flow of oxygen. This hampers the degradation process.
• Sanitation generally refers to the provision of facilities and services for the safe disposal of human urine and faeces.
• Poor sanitation causes a large number of diseases and health hazards.

Vermi-processing Toilet

• In this process, the waste sewage slurry collected from sewage disposal systems is treated with earthworms, wigglers and tiger worms.
• They decompose the faecal matter, kitchen waste (organic) and other household organic wastes.
• It is a very simple, hygienic and low water-consuming process with no odour or flies problem.

Septic Tanks

The septic tank is a buried, water-tight container usually made of concrete or polyethene, in which sewage is collected and allowed to decompose through bacterial activity before draining by means of a soak-away.

To know more about Sewage Management Methods, visit here .

Frequently Asked Questions on CBSE Class 7 Science Notes Chapter 18 Wastewater Story

What is sewage treatment.

Sewage Treatment refers to the process of removing contaminants, micro-organisms and other types of pollutants from wastewater.

What are the bacteria that cause water contamination?

The presence of coliform bacteria, specifically E. coli (a type of coliform bacteria), in drinking water suggests the water may contain pathogens.

What is vermin-processing?

Vermi refers to small worms such as earthworms. Vermi-processing toilets are those toilets in which human excreta is treated by earthworms.

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