Take waste out of water

For many years now India has been working, without much success, to ensure that our rivers are not polluted; that the sewage of our cities is treated before it is discharged; and that industries do not pollute.

In these climate-risked times, we need to recognise the urgency of this challenge — water will be scarcer as rainfall becomes more variable and erratic. We need to manage this stress, not only by capturing the rain in millions of waterbodies, but also by making sure that not a single drop of water gets polluted.

The good news is that our policies on rivers are evolving using the lessons from our failures. Today, the National Mission for Clean Ganga recognises that combating river pollution is not possible unless we can provide every Indian with working toilets, connected to systems that safely dispose of human excreta so it does not become another source of pollution and of bad health.

This agenda is, therefore, not just about building toilets but also about building sanitation systems that are affordable to all. Growth can be sustainable only when it is affordable and inclusive. This is our real challenge.

This challenge offers the opportunity to do things differently, and more effectively. Till now, the paradigm for urban sanitation has been costly. But the excreta sums of different cities, or what we call the city’s “shit-flow” diagram, show that the situation is grim. Our cities do not treat or safely dispose of the bulk of the human excreta. This is because we often confuse toilets with sanitation.

The fact is, toilets are mere receptacles to receive waste; when we flush or pour water, the waste flows into a piped drain, which could be either connected — or more likely not — to a sewage treatment plant (STP). This STP could be working, or not.

This means, human excreta (and our household waste) is mostly not disposed of safely. It is just discharged untreated into the nearest river, lake or a drain. This dirty water is responsible for the growing load of pollution, which in turn is leading to increased disease burden.

But, as I said, herein lies the opportunity. Instead of waiting for the underground sewer network to be built — which is expensive, unaffordable and frankly, given the economics of municipalities, unviable — there is another route for the excreta to flow. Today, the bulk of India’s households that have access to sanitation are connected to septic tanks.

These septic tanks, if well constructed, will retain the sludge and discharge the liquid through a soak pit. The faecal sludge can be emptied and conveyed for treatment.

The system would work if the septic tank is built to specification; if the system for collection of human excreta (faecal sludge) is regulated; and if the sludge, so collected, is taken to treatment points so that it can be made safe for reuse.

This sludge is rich in nutrients. The global nitrogen cycle is being disrupted because we dispose of the nutrient-rich human excreta into waterbodies. We can return the human excreta back to land, use it as a fertiliser and reverse the nitrogen cycle.

The faecal sludge, after treatment, can be given to farmers and be used as organic compost. Or, it can be treated and mixed with other organic waste, like kitchen waste, and used for biogas, or for manufacturing fuel pellets or ethanol.

We should learn from ancient Roma (Rome) and Edo (the city out of which grew Tokyo). The Romans used to build huge aqueducts that ran for tens of kilometres to bring water to their settlements. Many experts have praised the Romans for the meticulously planned water supply system.

But, no, these aqueducts represent not the intelligence but the utter environmental mismanagement of the great Romans. Rome was built on the river Tiber.

The city did not need any aqueduct. But as the waste of Rome was discharged directly into the Tiber, the river was polluted and water had to be brought from long distances. Water outlets were few as a result and the elite appropriated these using a system of slaves.

On the contrary, the traditional Japanese society never discharged their waste into the rivers. Instead they composted the waste and then used it in the fields. Using the rivers, Edo had numerous water outlets and a much more egalitarian water supply.

Water and culture go hand in hand. So, water shortage is not about mere failure of rain. It is about the failure of society to protect and share its water endowment.

The bottom line is that we cannot manage our rivers sustainably unless we fix our system of waste management. Our water future depends not only on our water wisdom, but also on our waste wisdom.

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