Excreta Matters: Monthly newsletter on Remedies start in small doses

Editorial: Remedies start in small doses

Last month, I suggested drastic surgery – open up the Yamuna River’s floodplains into one gigantic wetland, as in Kolkata, to improve water quality. It found little resonance with the government, maybe because there isn’t enough engineering (a person who had studied at IIT Delhi assured me it had) but it was too radical. But doesn’t a humungous problem call for drastic solutions? OK, so let’s propose something less radical, something that’s happening in dribs and drabs. Something that may even happen at a scale to make a difference.

So the Yamuna's 22 km stretch in Delhi gets sewage from 18 drains. It has no fresh water flows downstream of the wazirabad barrage in the lean months. It is a sewer. If we cannot operate on the main stem, we must on the feeder streams. Some have tinkered with the idea of using drains for sewage treatment and there are a couple of small projects to ‘try out’ the concept. It is time we moved ahead more aggressively to convert all drains into treatment zones. A few prerequisites, though, are in order.

First, small-scale units that electroplate or reprocess batteries and engine oil, dump their waste in drains. These eventually join one of the trunk drains that join the river. This is unacceptable and has to stop. One way is to move them to an industrial cluster fitted with a common effluent treatment plant. They will not pay and shutting them down is next to impossible. These units that employ a lot of people should be given a safer, better environment to operate. They do not pay taxes, operating under the government’s radar. While providing them a better place, the government should not ask questions, just stipulate their waste must be treated in a central location. If necessary, the government should operate the cluster and charge the units for power and water. If this is done sensibly, it can remove toxic waste from the equation.

Second, uncover the drains that were entombed in cement during an ill-conceived project of the Common Wealth Games. This was to hide the ugliness and eliminate the stench, but the end result is even higher levels of toxicity in the drains and the danger of concentrations of toxic gases trapped underneath that may build up dangerously. In their natural state, the drains provided a modicum of pollution abatement; covering them has deprived them of this.

Third, pick a large stretch, or the entire drain for treatment. Bits and pieces will not do since fresh pollution enters the drain downstream of the treated section, negating its benefits. We can use a mix of non-conventional treatment options for optimum results depending on the volume of water, rate of flow, aeration, composition of waste water, the area available for treatment, etc. The mix can change with the season, depending on what works best in summer or winter.

The treatment options include bio-remediation with enzymes or bacteria, soil biotechnology, constructed wetlands and green bridges. Each has its own advantages and disadvantages, science and costs. Each drain has unique characteristics that will need to be evaluated before picking a particular approach. These are, in the view of the government, experimental technologies that have been used in different circumstances. True, but they have been mostly effective in these circumstances and therefore, merit larger trials.

One problem is tendering for these technologies, a problem that crops up any time there is a new way to do something. It is easy to circumvent this by stating these are experimental and need to be tried to develop usage protocols from which tendering can evolve. There are large field trials running for each of these approaches that have been studied, and can inform the tendering process. There a constructed wetland and a soil biotechnology plant, each with a capacity to treated two million litres a day; a green bridge has been installed in Udaipur and bio-remediation has been used at several locations. An analysis of these will help decide a suitable mix of non-conventional approaches for in-situ treatment of sewage in drains.

There are many advantages of this approach. The drains will be cleaner and not stink or be eyesores. The water that seeps into aquifers from these drains will be cleaner and help reduce groundwater contamination from sewage. The drains can also become transport channels with paths for non-motorised transport as some architects and agencies have suggested, contributing to improving the quality of urban life. Finally, by improving the water quality in these drains, this work will ultimately help bring the Yamuna River back to life.