|| Home || Site Directory || Feedback || Send This Story To Friends ||  Support GNI ||


Regenerating water from organic waste.

Dr Jha of Sulabh has devised a neat way to recycle water used in toilets.

When the results of the first experiment were shown to Dr. Jha, he was unhappy. What he had set out to achieve was something amazing. The theoretical possibility was there, but the technology to regenerate water from organic waste was lacking. But he knew that if he persisted, the experiment would eventually show positive results. This technology when developed would save parched Delhi-ites, a minimum of two and a half crore litres a day. That's what the latest technology known as Sulabh Effluent Treatment Technology [SETT] would imply. The volumes are mind boggling.

The problem:

In Delhi alone by the end of the current financial year in March 2002, when the 1150 public toilet complexes get ready it will save around one and a half crore litres of water. Extend this technology to the existing 1000 complexes the figure that is derived is more than two and a half crore litres of water saved. What is more important is that this water that eventually joins the Yamuna is cent percent treated water that will not pollute the river already on its brink. Not just this! The technology can also be modified to generate biogas. More than 100 biogas plants constructed by Sulabh around the country are being utilised in lighting and as cooking fuel.

It has been a simple idea that worked for the Sulabh International Social Service Organisation known better for its Sulabh Public Toilet Complexes. Says Dr. P. K. Jha, Technical Advisor and the man behind the technology, "At the back of my mind, I was for long toying with the idea. I knew that with such a vast organic waste at our disposal, we could do it. But challenges lay elsewhere. It was in making the effluent free of disease carrying bacteria, odourless and colourless while at the same time retaining its value as a plant nutrient."

What gave it immediacy was the fact that Sulabh complexes in water scarce cities like Chennai and in parts of Andhra Pradesh were buying water for their needs. Something had to be done fast. Dr. Jha says aptly that as in other cases here too necessity was the mother of invention. Human waste is an organic compound. A major constituent of it is water. In addition, as people also take baths and wash clothes in Sulabh complexes, the water is deposited in safety tanks at the back. From here through the natural process of filtration water is discharged into the ground and for all practical purposes, wasted. The theoretical possibility of regenerating water existed but technology that was cheap and suitable for such a large scale was lacking.

Failure and then success:

Dr. Jha started working on a technology to generate water from human excreta last year. The first experiment involved heating waste at 65 - 70 degrees-C for a few minutes with biogas generated from its own complex. Though this process completely eliminated pathogens [disease causing bacteria] and the water was also odourless, it led to the loss of nitrogen which rendered the it useless for cultivation as well as pisciculture. The colour had also become dark. That apart it gave a pungent smell at the time of heating. The experiment was a failure.

It was then that the idea of using ultra violet [UV] rays struck him. Dr. Jha who did his PhD in Microbial Biochemistry from Patna University had studied the properties of UV rays while preparing his thesis. The exposure of a thin layer water to UV rays for a certain time completely eliminated the bacteria. To render it clear he used charcoal. When the organic materials were absorbed whatever colouration they caused also vanished. He finally succeeded in April, 2001. The treated water that now came out from the outlet pipe looked like any clean water. It was also free from odour.

Size of the promise:

Sulabh complexes now use this water for the purpose of cleaning floors. "As this water is not 100% pathogens free it is not recommended for drinking. Well, with certain modifications even this handicap can be overcome. but the mental barrier against this prohibits it," Dr.Jha says. "At least for the time being," he adds. It is a technique suitable for all kinds of organic wastes. However, its industrial application is limited to slaughter houses, meat washing plants, large dairy farms and poultry. Such industries can adapt this technology as it lessens their dependence on external water supply to the extent of 60%. It does not work in the case of chemical effluents.

This technology is something our country as a whole must adopt. Arriving at an all-India estimate is difficult. But let's try. Our calculations go something like this: There are about 4,500 Sulabh toilet complexes in the country; add to that at least the same number of other complexes. Now add at least 1000 more complexes at bus stands, railway stations, hospitals, housing colonies in small towns that do not have castly sewage systems, but instead use safety tanks. The total number comes to more than 10,000. According to Dr.Jha on an average each complex uses about 15,000 to 20,000 litres of water per day. If we keep the recovery of water to 60% only, the saving per day comes to 12,000 litres from a single complex. Multiply this by the total number [ 12,000 x 10,000 ], the volume we arrive at is 120,000,000 litres per day.

In this age when wars of the future are visualised to be fought over water, our country could well do its share keep itself out of it. All this at a price tag of Rs. 2 lakhs per complex. If you want to, you can even claim a subsidy of 75% offered by the government.


Director General,

Sulabh International Institute of Technical Research and Training

Sulabh Bhawan, Mahavir Enclave,

New Delhi-110 045, (India)

eMail: sulabh1@nde.vsnl.net.in

Phones: 5032617, 5032631, 5032654

Fax : (091-11) 5036122, 5034014


This article by Anand Jha appeared in the January, 2002 issue of 'Grassroots', by whose kind courtesy it is reproduced here.

The details of SETT described in this article do not as yet appear at the Sulabh web site. There is however, information on other related technologies developed by them at this address.