How large is the problem of urban sanitation in the world today?
Sanitation in urban areas of the world has reached a crisis point. Current predictions indicate that in 20-30 years' time, a majority of the world's population would reside in urban squatter colonies. These people are often not acknowledged by the municipal authorities, and the latter do not provide them with any services.

Water shortage too would definitely be a cause for concern in the 21st century. It is already a source of worry. Under such circumstances, it is unfair to flush 15-20 litres of fresh drinking water every time one uses the toilet. Problems related to urban sanitation and water shortage, like many other problems, are directly linked to population and its density.

If this is such a large problem, is not the world of scientific research actively pursuing the issue, looking for solutions to urban sanitation?
Unfortunately, it is not doing as much as it could have. Though I do not have ready figures, the amounts being spent on research would probably be around us $2 million a year. The world seems to have accepted the flushing system as the most effective method of dealing with the problem. ironically, the flushing system used today is an 18th century technology and we are content with seeing different models and colours as 'innovations' to this.

Where according to you does the main problem lie?
As I had said earlier, squatters would be the biggest source of worry in the years to come. The problem has already reached alarming proportions in metropolitan cities, like Delhi. And with these people defaecating in open areas, along roadsides, others should realise that the question of sewage not being properly disposed could have serious health problems for those living nearby.

But the main problem, I think, is our system of sanitation. Nature, in its infinite wisdom, has maintained separate channels of disposing excreta and urine within the human body. We make the basic mistake of mixing the two and adding it to water.

The outlet from individual toilets joins others in larger sewage drains which, after joining yet larger drains, is generally let into water bodies like streams, rivers or lakes, which constitute major sources of drinking water. Very little of the sewage is actually treated.

Nitrogen in the water from human waste, along with the nitrogen in industrial pollutants, increases every day while the size of water bodies and their ability to absorb the nitrogen remains the same.

What could be the immediate solution for such senseless dumping?
There are no easy solutions to this issue. The costs involved in dealing with it properly are prohibitive, and most municipalities and governments have other issues which command higher priority.

Instead of having large treatment plants, which are designed to handle waste from several areas in a city, on-site treatment, which would deal with a limited number of houses, must be encouraged. But even in this, there is a problem. The world's population can be divided into two categories; washers and wipers. While it is easier to deal with the latter category, the former are quite difficult to control, as their work usually has its roots in tradition and taboo. India and many parts of the African continent face this problem.

In India, for example, human waste is considered utterly dirty, even one's own waste. It would be an uphill task to try and convince people to alter the way they deal with it. The same goes for Africa. People's attitudes must change. That has to be the starting point.

From what you have observed, how do people in various parts of the world look upon the problem of human waste?
As I have just mentioned, in countries where taboos are strong, the municipalities and governments have a lot of work ahead. Traditionally, wipers are open to change. This was why we were able to carry out experiments in countries like Mexico and San Salvador, where for the past four years, we have been able to successfully implement a system termed dessication.

In the Far East, especially in China and Japan, human waste has always been considered a resource. In China, where they have been cultivating the same lands for the past 4,000 years, they have used human waste as fertilisers. Farmers who owned lands along roadways used to maintain clean toilets in the hope that travellers would use them. Urine, for example, would be mixed with water and sprinkled in their fields.

This same practise is followed in Sweden today, where urine is stored in separate tanks, and farmers collect this for use in their fields. Also, a system called clivus multrum has been in use. The West has understood waste to be a part of a cycle, which can be used as a resource.

How do the two systems, dessication and clivus multrurn work?
Both involve the breaking down of pathogenic organisms at different temperatures and are different composting techniques. In dessication, solid and liquid wastes are not mixed. The humidity required is about 20-30 per cent. Pathogenic organisms are killed by solar energy and the contents get dried. The unit need not be underground and a dessicating unit can be set up in both luxury and ordinary apartments, on any floor. And the smell is no problem either.

In clivus multrum, household liquid waste and organic wastes are mixed with solid human waste for composting. Here the process of decomposition reduces the heap to less then 10 per cent of the original volume. The collecting pit slopes downward so that it is easy to remove the decomposed material. Humidity needs to be maintained at 60 per cent. In Germany, a system for 800 household units has been developed. Both these are on-site systems.

While these two systems have not replaced existing sewage systems, they have been able to show planners that there exists an alternative that can be implemented. Besides, there is a financial spin-off, because human waste is also a useful product: it is organic manure.

What work are you currently involved in this part of the world?
The World Health Organization has undertaken a study, on the health of rural school children. I am working in rural Rajasthan, where I have to draw up a set of guidelines for primary school children. This is part of an international survey, the draft report of which is to be released in June '96.

Sanitation at the school level is directly related to what we have been talking about. In comparison with certain parts of Africa where I have done similar work, I find very few schools in India with sanitation facilities. After this compilation, there is a study that has to be undertaken in Vietnam, where there are 10 million boat people who live on the country's rivers. The wastes go directly into the rivers and this has been recognised as a potentially dangerous practice.

Gandhiji was an inspiration to us in the West, with the way he tried to humanise the issue in a country where human waste and anything to do with it was considered almost subhuman. For making any headway, it would be necessary to acknowledge sanitation as a problem. Only then would it be possible for any progress to be made on that front.