Technology

Water is life, essential for daily sustenance and healthy living. With plummeting groundwater levels, contamination of water sources and increasing consumption, challenges in the water sector have increased manifold. Safe, sustainable and affordable water in the face of growing water needs is a severe challenge. With fresh water supplies already hard pressed to meet growing demand, technology plays an important role in managing and using the limited available water in a cost effective and critical manner.

Water contamination occurs both due to human activities and natural processes. Depending upon the purpose for which the water is needed--municipal, industrial or agriculture--treatment is carried out. The technology used will depend upon the current water quality, future standards required and economics of the treatment method. Water treatment removes contaminants that may be biological, physical or chemical in nature. 

Various water treatment technologies are present that purify polluted water by removing undesirable chemicals or biological contaminants and making it fit for human consumption. Use based classification of surface waters in India has been laid down by the Central Pollution Control Board (CPCB). The details of the permissible and desirable limits of various parameters in drinking water as per Bureau of Indian Standards (BIS) standard specifications for potable water are also detailed in the IS 10500:1991

Water treatment plants use technologies to produce water that is safe both chemically and biologically, and that is appealing in terms of colour, odour and taste. The control point for water quality determination must be the consumer's tap and not the treatment facility, which means that the water quality must not be impaired during transmission, storage and distribution to the user. The treatment methods at the plant include aeration, coagulation and flocculation, sedimentation, filtration and disinfection.  Some of the prevalent water purification & treatment technologies are listed below.

  • Capacitive Deionization (CDI) is a technology where ions are removed from water by passing it through a spacer channel with porous electrodes on each side
  • Ozonation is a chemical water treatment technique based on the infusion of ozone into water
  • Ultraviolet technology uses Ultraviolet light, just like sunlight, to kill micro-organisms present in the water
  • Reverse Osmosis (RO) is a technology that removes a large majority of contaminants by pushing the water under pressure through a semi-permeable membrane
  • TERAFIL is a burnt red clay porous media used for filtration & treatment of raw water into clean drinking water, developed Council of Scientific & Industrial Research (CSIR), Bhubaneshwar 
  • OS- Community scale Arsenic Filter is an organic arsenic filter, developed by IIT Kharagpur
  • Filtration methods that may include rapid/ slow sand filters remove dirt, rust, silt, dust and other particulate matter from water
  • Solar water purification systems 

Water treatment technologies for safe, potable water in rural areas that includes Capacitive Deionization Technology (CDI) using carbon aerogel, solar operated groundwater treatment plants and electro chlorination are described in a booklet ‘Compendium of innovative technologies on rural drinking water & sanitation’ by the Ministry of Drinking Water and Sanitation. 

Domestic drinking water filtration methods vary depending upon the method of purification used, the degree of ‘purity’ required, and the type of contaminants in the water. No one technology will fulfil all criteria--there is no ‘silver bullet’ solution. Some of the more popular methods for Household Water Treatment & Safe Storage (HWTS) options includes boiling, SODIS (Solar disinfection), Chlorine Tablets, Liquid Chlorine (online, Biosand filters, Flocculent treatment, Ceramic candle, Filter combinations, Pureit filters, Ultra Violet (UV) filters, Reverse Osmosis (RO) and Ion Exchange (IEX).

For more on water purification systems, click here.

Domestic Greywater Recycling Water filtration technologies

Any used water, other than sewage from toilet basins that exit a house or apartment complex, is referred to as sullage or greywater. This is mostly made up of water used in bathrooms and kitchens, constituting the bulk--nearly 60%-70%--of the total volume of water used in a day. 

Before underground sewerage was introduced in most cities, water followed a cyclical route. Water was drawn from dug wells within the premises. Refuse water from the bathrooms and kitchen was let out into the garden while water from the closets reached septic tanks. The soil treated the greywater and sent it back into the ground, thereby closing the household water consumption-reuse loop.

Contrary to popular belief, greywater is largely free from pathogens. As it is mostly made up of easily degradable organic waste and chemicals from cleaning products, it can be purified and reused in-situ with minimal effort. In many homes and apartment complexes, sending this perfectly reusable resource out of the plot along with sewage common-sight. Greywater can be brought back into the water cycle by employing simple biological and mechanical filtration techniques.

There are two basic requirements apart from the necessary plumbing arrangements for treating domestic wastewater:

  1. Open soil space
  2. Water loving plants

Water from bathrooms and kitchens can be diverted through a dedicated pipeline into the plant bed set aside for the treatment process. Here, the nutrients present in the waste water are absorbed by water loving plants such as Canna or Cyperus while the soil bacteria polish off the organic waste from the water. 

  • Constructed wetlands – These wetlands are created to replicate the process of bio-filtration that occurs in a natural setting. Here, the water is purified using two media, the planted surface and the gravel bed underneath. 
  • Reed bed treatment plants – A smaller version of the constructed wetlands, reed beds are perfect for individual houses and smaller complexes.
  • Mechanical filtration – Mechanical systems such as sand filters and pebble flow systems can be used to help filter out waste from the water by separating the discernable solids from the liquid component. 
  • Lava filters – These pebble filters are a combination of both biological and mechanical systems where the stones act as support structures for microorganisms that help break down the waste. 

For more on the basics of rainwater harvesting and greywater recycling, refer Self reliance in water: A book by Indukanth Ragade.  

Sewage treatment--Municipal and Industrial

Waste water flowing out of urinals and toilet closets are referred to as ‘blackwater’ or sewage. Blackwater cannot be treated in the same way as greywater as the former contains a heavy pathogen load from the fecal matter suspended in it. Sewage from towns and cities flowing directly into water bodies is one of the major reasons for water pollution.

Municipal wastewater treatment plant, Yelahanka, Bangalore

While City Corporations are in charge of laying underground sewerage pipes to collect, channel and treat sewage, localities outside city limits have a greater responsibility of managing their own waste. Apartment complexes and townships mostly rely on small scale sewage treatment plants (STP) to treat their waste.

Wastewater can be treated either in the presence or absence of oxygen. While aerobic digestion involves the breakdown of waste by microorganisms in the presence of oxygen, anaerobic systems work in its absence. Various types of processes are used to treat both domestic and industrial waste water such as:

  • Activated Sludge Process where biological agents such as bacteria are used in the presence of air to oxidise the nutrients present in the sewage 
  • Sequencing Batch Reactors help equalize, aerate and sediment waste water in timed batches by mixing it with activated sludge and oxygen to reduce the organic load 
  • Membrane Bio Reactors provide a higher degree of organic and solid removal by combining the principles of both mechanical filtration and biological digestion to treat municipal waste 
  • Moving Bed Bioreactors are mainly used for aerating and treating high-strength wastewater where several floating polyethylene bio-films move in suspension provide surface area for the nutrient-digesting bacteria to grow 
  • Trickling filters are low-cost, aerobic systems made up of a fixed bed of gravel, rocks and moss over through sewage is passed to remove the nutrient material in the suspension 
  • Facultative aerated lagoons are shallow ponds where the sewage is allowed to with the atmospheric oxygen in the upper layers while the sludge settles down at the bottom 
  • Waste stabilisation ponds, categorized into three broad types – anaerobic, facultative and aeobic depending on the oxygen use intensity – help in reducing nutrient content and polishing waste water to re-use quality 
  • Up-flow anaerobic sludge blanket digestion treats wastewater in the absence of oxygen where the feed enters the tank through the bottom and flows upward as the bacteria present in the sludge digest organic the matter 

The CPCB publication on the status of sewage treatment in India throws light on the performance of sewage treatment plants across the country and the technologies currently being used in them. The status of waste water generation and treatment across the country is also available on the ENVIS Centre on hygiene, sanitation, sewage treatment systems and technology. 

  • Ahead of UNCCD COP14 in Delhi this week, India pledges to restore 5 million hectares of degraded land by 2030 For the first time, India is hosting the 14th Conference of Parties (COP 14) of the United Nations Convention to Combat Desertification (UNCCD) from September 2nd to the 13th in New Delhi.&...
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  • Centre to provide 43-55 litre/day water per person to rural households by 2024 Under the Jal Jeevan Mission, the Centre plans to provide 43 to 55 litres of water per person per day to every rural Indian household by 2024, and to set up a dedicated fund called Rashtriya Jal Jeevan Kosh f...
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  • How to use STP treated water for agriculture? What are the permissible parameters ?
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  • India is reeling from a severe water crisis. Large parts of the country are experiencing water-stress worsened by the ever increasing demand for water due to population growth, rapid urbanisation, changing lifestyles and consumption patterns, inefficient use of water and climate change. While curr...
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  • A pig snorts after emerging from the open drain that passes through a slum in the Digha area of south Patna. Small children crawl on the road nearby with slime dribbling from their nose. Children can be seen picking through garbage at the local dump and for ghongha (snails) at the local talaab ...
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  • Drinking water programs in India treat urban and rural areas separately, generally neglecting the special characteristics of settlements referred to as peri-urban – those on the outskirts or peripheries of urban areas, or “rurban” settlements i.e. rural areas with urban facilities. A study - ...
    Amita Bhaduriposted 4 months 2 weeks agoread more
  • We had dug a borewell in February and it yielded water. But we did not use the borewell for 6 months and now the bore well has dried up ( even after the rains of July). Is there a possibility to revive the borewell?
    Anonymous (not verified)posted 4 months 3 weeks agoread more
  • I am having unused borewell of depth 350 feet and 8inches dia. We left the borewell unused for more than 10 years for less water & drought. And surrounding water table gone up to 500 feet, 600 feet, 700 feet deep. Suddenly we checked the borewell, we came to know that the borewell has water at 2...
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  • Is there a device that I can buy to measure the noise level? I need help measuring the STP noise as the STP is below my house and the Association is not willing to rectify it as they say its below the recommended db levels.
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  • Since the 25th of July, there have been four consecutive weeks of surplus rainfall which have compensated for the delayed onset of monsoon and the deficient rains recorded in June and early July.  July had ended with a countrywide deficit of 9%, but vigorous Monsoon conditions took the rains to...
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  • A study published in the Journal of Remote Sensing and Space Sciences, analyzing the cooling effect of the city of Ahmedabad’s water bodies, has thrown up some interesting findings. The east bank of the Sabarmati river, which flows through Ahmedabad, was found to be significantly cooler than the w...
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  • We are constructing a residential building project  in Burdwan, West Bengal. So, we want to install a rainwater harvesting system and recharge pit. To whom shall we contact regarding this.  
    Anonymous (not verified)posted 4 months 3 weeks agoread more
  • I am planning to buy a land in Chennai. The developer says each plot owner have to build septic tank for sewage and also borewell for drinking water. Will the grey water from the septic tank leak and pollute the borewell. There are multiple plots. I want to know how to protect borewell water, as it ...
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  • Rains wreak havoc in Uttarakhand, Himachal Pradesh and Punjab Following the southern states witnessing heavy rainfall and floods this monsoon, the northern parts of India are now also experiencing incessant rains. At least 28 people are feared dead and 22 missing in Himachal Pradesh, Uttarakhand...
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  • Hi, I have an independent house with three families. My plot size is 30×60 feet. I don't have a borewell. I am looking for water recycling that I can use it for flushing of toilet. Can you suggest some plan for this. I am from Hyderabad.
    Anonymous (not verified)posted 5 months 8 hours agoread more
  • Government to spend Rs 3.5 trillion under Jal Jeevan Mission: PM Modi In his first Independence Day address to the nation after the National Democratic Alliance (NDA) government came back to power, Prime Minister Narendra Modi flagged the growing water crisis in the country and said that around Rs....
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  • Worldwide, the demand for energy has risen significantly and quickly, leading to serious impacts on environmental sustainability and hindering global efforts to mitigate climate change. Hydropower, a leading renewable option has the additional benefits of water storage for agriculture and other uses...
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  • Besides showcasing the architectural expertise and aesthetics of their time, temple tanks also play an extremely important role as water storage systems in Chennai. Chennai has 39 temple tanks (excluding the suburban area) according to a study conducted in 2008.  As the rains arrived, a few tem...
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  • The videos were all over the Internet and social media. Expectedly so, because you don’t often see crocodiles swimming in flooded urban streets, sneaking up on strays. But that’s precisely what happened shortly after news of ‘urban floods’ in Vadodara hit headlines in early August. The city ...
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  • Hello, My three year old borewell with 450 depth is now getting black and yellow colour, smelly water. Kindly guide me how we can fix this? I have no other source for water. Will bore cleaning help? Pls guide me (the neighbouring house 500 meter away from me is selling water but they never faced th...
    Anonymous (not verified)posted 5 months 1 day agoread more

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A large amount of waste residue can be generated in the process of sand and stone production, and a lot of wastewater which casued serious pollution to the river water body can be produced. So what should be done to resolve this problem?

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Study identifies 5,000 illegal e-waste units in Delhi operating without health and environmental safeguards.

A study by Toxics Link, a Delhi-based environmental research and advocacy non-profit identified 15 e-waste processing hotspots in Delhi operating with impunity without safeguards. These hotspots house over 5,000 illegal e-waste processing units directly and indirectly employing over 50,000 people. The sheer scale of the violation of environmental norms highlights the failure of the system, especially of the E-waste (Management) Rules 2016.

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Groundwater use has doubled in Pune. Comprehensive mapping of groundwater resources and better management and governance is the need of the hour.

Pune continues to face a water crisis every summer despite having sufficient water, thanks to its geographical location and plentiful natural water assets. While enough of its water needs are taken care of by water supply from the Khadakwasla dam, the use of groundwater to meet the needs of the population continues to increase.

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While ice stupas have been hailed as sustainable solutions to the water problems of Ladakh’s villages, the locals think otherwise.

Ladakh, the arid Himalayan desert, is a high elevation borderland located close to the Union Territory (UT) of Jammu and Kashmir, in India. Water here originates from glaciers in the high altitude mountains that tower over Ladakh’s villages. Simple earthwork irrigation channels tap meltwater from streams that originate from these glaciers. The glaciers are extremely sensitive to seasonal variations and serious concerns have been raised in recent years on the impact of climate change on glacier recession and the subsequent sustainability of water resources in the region.

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An intern with Watershed Organisation Trust narrates his field experience from the villages of Madhya Pradesh, where farmers are using farm ponds to conserve water.

Madhya Pradesh, promoted as 'The Heart of India' by the state's tourism board is aptly named so because of its central location. The campaign made me keen to visit the state, for the last many years.

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News this week

Soon a national framework for e-flows in all major rivers

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A forum discusses the need to stop illegal land transfers and land alienation of the poor.

Land-related conflicts in India are on the rise despite some of the most progressive legislations to protect people’s rights over land and forest. Land and forest rights experts and activists from 13 Asian countries including India attended the annual Asia Land Forum, organised by the International Land Coalition Asia. The forum is organised every year, this year’s theme being ‘Land reform for peace and justice in Asia’.

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About the conference:

The thirteenth annual Global Water Alliance Conference is organized jointly with Rural Development Forum, The Institution Of Engineers (India) in partnership with Indian Institute Of Engineering Science And Technology, Shibpur on the theme of “Achieving Water, Sanitation And Hygiene (Wash) Sustainability Goals For Developing Countries” on January 4-7, 2020, Kolkata, India. 

Conference theme:

January 4, 2020 9:00AM - January 7, 2020 6:00PM

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In this interview, Joy talks about his work as an activist working in rural Maharashtra, and how he came to work on water conflicts in India.

To many in the water sector, K. J. Joy needs no introduction. An activist at heart, Joy is known for his untiring rights based work in mobilising communities in rural Maharashtra, and for his research work on water and water related conflicts including inter-state riparian water conflicts.

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A study using remote sensing techniques assesses significant changes in land use in Loktak lake.

Loktak, the largest freshwater lake in North East India is also known as the ‘floating lake’ for the numerous phumdis or masses of vegetation it supports. The phumdis float around on the lake’s surface due to decay from the bottom. Some are so large that the indigenous fishing folk Meiteis have constructed makeshift floating huts locally known as phumsangs on them.

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