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. 

  • Floods are an annual phenomenon in Assam. They are as integral to the state as the Brahmaputra River is, and each monsoon, we are reminded that Assam exists (or is drowning). As I write this piece, Assam is slowly recovering from the first wave of flood this monsoon. For several weeks, the entire st...
    priyadposted 1 day 14 hours agoread more
  • Agricultural extension and advisory services facilitate the transfer of knowledge, information, improved technologies and practices to farmers, farmer organizations and market actors. Research has shown positive effects of extension access when it came to knowledge, adoption, productivity, and econo...
    Amita Bhaduriposted 1 day 15 hours agoread more
  • Southwest monsoon claims 227 lives At least 227 people across the country have been reported dead in floods, lightning and landslides occurring due to the southwest monsoon. With 80 casualties, Kerala is the worst affected state in the south. Several parts of Gujarat, including Saurashtra and ...
    swatiposted 6 days 14 hours agoread more
  • Government rolls out plan to revive springs across the country The Jal Shakti Ministry has proposed a pilot project for spring inventory and rejuvenation in the Tehri Garhwal district of Uttarakhand, and has suggested that similar projects of springs management be taken up in rest of the country wi...
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  • P Sainath has been documenting stories from rural India for over three decades now. He is the founder-editor of People's Archive of Rural India (PARI), a digital archive dedicated to people whose voices and stories don't always find space in mainstream media. Sainath previously covered the rural bea...
    priyadposted 1 week 15 hours agoread more
  •  The East Kolkata Wetlands (EKW) are a truly unique ecosystem, presenting a very different sight from the normal urban landscape in India. What is so unique and different about them, and how have they survived the aggressive growth of Kolkata city? The credit goes to Dr. Dhrubajyoti Ghosh, a...
    aarti kelkar kh...posted 1 week 5 days agoread more
  •  Over 3.5 lakh water conservation measures taken up in a single month as nationwide Jal Shakti Abhiyan hits ground In a countrywide effort to enhance water security, especially in water stressed districts, the Centre initiated Jal Shakti Abhiyan (JSA) has reported over 3.5 lakh water conservat...
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  • Government to 3D map aquifers in all villages Union Jal Shakti Minister Gajendra Singh Shekawat said that the Centre is carrying out 3D aquifer mapping of every village in India, to help target water conservation measures at a micro level across the country. Such an exercise will help the governmen...
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  • Chennai had a severely deficient monsoon in 2018 with 40% less rain than normal. Since then, the city has been bracing itself for a water crisis. But clearly not enough had been done and the severe water scarcity this summer has been a wake-up call for people, highlighting the urgency of finding way...
    priyadposted 1 week 6 days agoread more
  • Vishwanath Srikantaiah, popularly known as the 'Rainman', has been in the news recently for his ambitious project to build one million recharge wells in Bengaluru. Given the dire situation we find ourselves in vis-à-vis water, the initiative could not have come at a better time. While Vishwanath h...
    priyadposted 1 week 6 days agoread more
  • Alia, 15, cannot move or talk. “She is totally dependent on me,” said her father Mohammad Asad, an electrician. “Her mother passed away almost nine years back. I have to remain with her most of the time”. Even 35 years after the world’s worst industrial disaster that claimed 3787 lives in...
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  • Lok Sabha passes Inter-State River Water Disputes (Amendment) Bill, 2019   The Lok Sabha has passed the Inter-State River Water Disputes (Amendment) Bill, 2019, which seeks to amend the Inter-State River Water Disputes Act of 1956. The bill proposes to set up a central tribunal to help...
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  • Centre for Science and Environment (CSE), a New Delhi based non-profit has rated the country’s fertilizer sector on several parameters, in a first of its kind study. The rating, done over an 18-month-long process, covered 28 of the 32 functional fertilizer units in the country. The findings of thi...
    Amita Bhaduriposted 2 weeks 13 hours agoread more
  • Maharashtra is reeling under drought this year too, with the situation in Marathwada particularly bad. As high as twenty four out of thirty six districts in the state are facing deficient monsoons and about 4,920 villages and 10,506 hamlets are now completely dependent on water tankers for drinking ...
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  • Regionally and globally, soil erosion is a major contributor to total land degradation. Its impact is more pronounced in rainfed areas and it is a major threat to agriculture in India, with a significant economic cost amounting to about 0.35% of GDP in 2014-15 as per estimates by TERI (2018). Con...
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  • Himalayan states demand green bonus and separate ministry from Centre At the recent Conclave of Himalayan States, a separate ministry was demanded to deal with problems endemic to the mountain states, as well as a green bonus in recognition of their contribution to environmental conservation. ...
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  • There are studies and field reports that have analysed the Swachh Bharat Mission (SBM) in terms of coverage and use of toilets in rural India. The official government survey, the NARSS 2018-19, shows that 93 percent of rural households have access to a toilet and 96 percent of those having a toilet ...
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  • Diviner mentioned water table 250- 300 ft. Borewell depth = 500 feet. Dia. 6.5 inch. Strata weathered rock. During drilling no water seen. 1 day, water column height was 112 ft, 3 days: 156.5 ft, 4 days:192 ft, and 5 days: 220 ft. We would be happy to get 750 liters per shift x 2...
    Anonymous (not verified)posted 3 weeks 2 days agoread more
  • If the water pump is not used for a long time, will it stop working? If so how often should I use the pump?
    Anonymous (not verified)posted 3 weeks 3 days agoread more
  • I am planning to build a house in a 30 X 40 site in Bangalore. I would like to incorporate a cost effective grey water recycling and rainwater harvesting system. Kindly let me know how do I go about it since I am at the design stage of the project. Thanks
    Anonymous (not verified)posted 3 weeks 3 days agoread more

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Mitul Baruah from Ashoka University narrates personal experiences of people affected by floods in Majuli, Assam.

Floods are an annual phenomenon in Assam. They are as integral to the state as the Brahmaputra River is, and each monsoon, we are reminded that Assam exists (or is drowning). As I write this piece, Assam is slowly recovering from the first wave of flood this monsoon.

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Mobile agri-advisory services provide timely and relevant advice to farmers. But do they translate to practice in the field?

Agricultural extension and advisory services facilitate the transfer of knowledge, information, improved technologies and practices to farmers, farmer organizations and market actors. Research has shown positive effects of extension access when it came to knowledge, adoption, productivity, and economic returns for farmers. The high cost associated with face-to-face extension constrains effective service delivery to farmers, who are often widely distributed spatially.

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News this week

Southwest monsoon claims 227 lives

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Policy matters this week

Government rolls out plan to revive springs across the country

The Jal Shakti Ministry has proposed a pilot project for spring inventory and rejuvenation in the Tehri Garhwal district of Uttarakhand, and has suggested that similar projects of springs management be taken up in rest of the country with the active involvement of several other ministries.

Topics

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Magsaysay award winner & founder-editor of PARI, P Sainath analyses India's water scarcity, the agrarian crisis & farmer suicides, before asking: what can we do about it?

P Sainath has been documenting stories from rural India for over three decades now. He is the founder-editor of People's Archive of Rural India (PARI), a digital archive dedicated to people whose voices and stories don't always find space in mainstream media. Sainath previously covered the rural beat at The Hindu, and his on ground reportage has drawn significant attention to the country’s farmers and the challenges they face.

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A real estate boom is tightening its grip on the East Kolkata Wetlands, a unique waste processing ecosystem. Cooperation and coproduction, not conflict are needed to save them.

 The East Kolkata Wetlands (EKW) are a truly unique ecosystem, presenting a very different sight from the normal urban landscape in India.

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Regions

News this week

Topics

Sub-Categories

Regions

Policy matters this week

Government to 3D map aquifers in all villages

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Regions

Chennai residents take matters into their hands in a novel initiative

Chennai had a severely deficient monsoon in 2018 with 40% less rain than normal. Since then, the city has been bracing itself for a water crisis. But clearly not enough had been done and the severe water scarcity this summer has been a wake-up call for people, highlighting the urgency of finding ways to use their water resources better.

Topics

Sub-Categories

Regions

A million recharge wells for Bangalore

Vishwanath Srikantaiah, popularly known as the 'Rainman', has been in the news recently for his ambitious project to build one million recharge wells in Bengaluru. Given the dire situation we find ourselves in vis-à-vis water, the initiative could not have come at a better time.

Topics

Sub-Categories

Regions

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