Lakes of fire

The froth spewing from them in Bengaluru is a symptom of a pervasive urban problem — the discharge of untreated sewage into water bodies.

Written by Isher Judge Ahluwalia , Almitra Patel | Published:August 30, 2017 12:52 am
Water pollution, Bellandur lake, Bengaluru lake, Bengaluru lake pollution, bangalore lake According to the CPCB, 75 per cent of the measured pollution in our rivers from point sources is from municipal sewage and 25 per cent is from industrial effluents. (Illustration: C R Sasikumar)

Bellandur lake in Bengaluru has been much in the news in recent months for the surge of foam and froth from the polluted lake, and the rise of smoke and flames from the area surrounding it. Barely two weeks ago, in the midst of the city’s heaviest rains in a century, the stinking froth and foam (a mix of chemicals and untreated sewage) rose as high as 10 to 12 feet from Bellandur and spread onto the streets, endangering traffic and entering shops and homes across the road, causing huge inconvenience to those living in the area. Only a few months earlier, in February, the area was engulfed in smoke as garbage strewn around the lake was set ablaze.

In May 2015, the Bellandur lake itself was on fire, creating enormous fear and anxiety in the minds of the people living in the area. The Central Pollution Control Board (CPCB) submitted a report to the Union Ministry of Environment, Forests and Climate Change, highlighting the sustained inflow of untreated sewage and industrial effluents as the principal forces behind the phenomena of froth and fire. Subsequently, an expert committee set up by the state government submitted its report on rejuvenation of the lake in October 2016.

How long would it take to get down to action? It is hard to believe that this is happening to the largest lake in the Silicon Valley of India, which has been known for its hundreds of lakes originally built in the 16th century by damming the natural valley systems. The National Green Tribunal turned its attention to the problems of the Bellandur lake in February, and expressed extreme dissatisfaction on the unhealthy condition of the lake in its successive hearings. The tribunal has issued a number of directions emphasising the need for removal of silt from the lake, treatment of municipal sewage which is going into the water body, closure of polluting industries, ban on dumping of municipal solid waste around the lake, penalty on apartment buildings in the area which are sending untreated sewage to the lake and an environmental fine of Rs 5 lakh on anyone found dumping waste in and around the lake. Most recently, the NGT has asked all departments of the government to work together to prepare an Action Plan by September 7 for cleaning up the lake.

Bellandur is only one example, although a major one, of what we are doing to most of our lakes, streams and rivers in urban India. Out of 480 million litres per day (MLD) of wastewater discharged to the lake, only 308 MLD is treated. According to the CPCB, 75 per cent of the measured pollution in our rivers from point sources is from municipal sewage and 25 per cent is from industrial effluents.

Indian cities and towns have abused their surface water bodies. Sewerage networks are supposed to ensure that sewage or wastewater is conveyed to a sewage treatment plant, treated and then discharged into water bodies. Bengaluru has 6,800 km of sewerage line and 14 sewage treatment plants. The capacity for sewage treatment in Bengaluru in 2015-16 was 51 per cent but actual sewage treatment was only 37 per cent of the sewage generated. This is still higher than the 30 per cent average for all Indian cities and towns.

Since the “unofficial” groundwater that is used by city residents from private bore-wells is not included in the definition of water consumed by the city, wastewater or sewage (estimated as 80 per cent of the water consumed in the city) is typically under-estimated. The situation with respect to sewage treatment is therefore worse than it appears for all cities.

As the untreated wastewater or sewage finds its way to local waterbodies, it feeds the growth of water-weeds, which blankets surface water. Aquatic vegetation is an orphan waste, not yet covered by the rules under the Environment Protection Act 1986. Apparently, the huge roots of water hyacinth absorb impurities and can lock up pollutants in the water. But when this profuse aquatic vegetation dies, it sinks to the bottom and decays. The microbes feeding on the rotting organic matter consume all the oxygen in the water, disturbing the ecology for the survival of fish life. When such organic matter naturally breaks down, it releases fatty acids that float to the surface. These act as natural surfactants, which allow minute bubbles to form which often persist for a long time. This is how foam is formed and turns into froth.

Surfactants are clearly a cause of foam formation. That is why detergent companies deliberately use surfactants to create foams that lift off dirt and have a feel-good factor for detergent users. The problem arises when these surfactants are not biodegradable and do not break down after their purpose is served.

In the late 1950s and the 1960s in the United States, lakes, rivers, and sewage treatment plants experienced foam formation, caused by synthetic laundry detergents that were highly resistant to chemical breakdown. Now, by law, the lathering agent of all detergents on the market must be biodegradable. They therefore quickly lose their ability to cause foaming and are unable to produce long-lasting foam. We need similar regulations in India, that is, the surfactants in detergents must be biodegradable.

It is the phosphorus in detergents entering wastewater which hugely promotes the growth of water plants. Phosphorus is useful for agriculture, but it is directly responsible for choking our surface waters with aquatic vegetation. It is also indirectly responsible for forming huge rafts of foam which get stabilised by rotting vegetation on the lake bottom.

The problem was first identified when Lake Erie, on the US-Canada border, turned green and its aquatic life began dying for want of oxygen, as dying plants sank to the bottom and rotted, consuming dissolved oxygen from the water. This is called eutrophication. Both countries rapidly responded with an international treaty in 1970 which, has since 1973, limited the phosphorus content in their detergents to a maximum of 2.2 per cent. The European Union followed suit.

India has no mandatory rules limiting phosphorus content in detergents and laundry bars, even as demand for detergents has grown at the rate of 10-11 per cent per annum between 2005 and 2010, and is likely to have been faster in the subsequent years because of rapid urbanisation. The phosphorus content in the detergents in India is much higher than 2.2 per cent. It is extremely important that a lower limit closer to the global norm is placed on phosphorus content and its labelling becomes mandatory for all detergents in the Indian market so that caring citizens can make eco-friendly purchasing choices.

In the recent crisis on the frothing and flaring in and around the Bellandur lake, far too much of press attention was placed on fire-fighting with bio-culture and/or water sprinklers and not enough on the factors that have brought us to this pass. There are no short-cuts to protecting our catchments for freshwater. Waste management is critical — solid waste (garbage), liquid waste (sewage), and acquatic waste. Additional challenges are posed by encroachment, which diminishes catchments for freshwater. Urban planning in India must ensure that wetlands which are natural recharge zones are typically not disturbed. Also, natural drains which provide a safe exit to storm-water including flood-water and also recharge ground water, should be protected from encroachment.

Ahluwalia is chairperson, ICRIER, Delhi, and former chairperson of the high-powered expert committee on urban infrastructure and services. Patel is member, Supreme Court committee on solid waste management

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