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Odorless Self-flushing Public Toilet for Slum Sanitation

Current Challenges

  • Higher use of drinking quality water.
  • Untreated sewage becomes a problem.
  • Conventional sewage treatment methods not suitable for slums in developing countries.
  • Production of sludge and greenhouse gases
  • Treated sewage is not fit for recycling.
  • Use of toxic chemicals to control odor, pathogens and pests


Eco-Logical Approach

  • Plants provide us with all of our necessities.
  • Plants flourish on human/animal wastes.
  • Hence toilet should have plant ecology.
  • Odor, pathogens and pests come only when we neglect this wisdom.



  • Natural granular bio-catalyst developed by BERI, Pune.
  • Goes to the root cause of pollution.
  • Converts pollution into resources, using time-tested natural biochemical reactions.
  • Small investment, no recurring charges.
  • No need of any machinery, electricity, skilled manpower, repairs and maintenance.


Odorless Self-flushing Toilet

  • Compact planted filter because of use of BIOSANITIZER
  • Produces water fit for recycling(flushing)
  • This water also has properties to control odor-pathogens-and pests.
  • Also acts as a plant tonic.
  • Value of about Rs 300/- per liter, because of above properties.


Odorless Self-flushing Public Toilet for Slum Sanitation

- Vag Shantharam Shenai*,
Green Cross Society,
Mumbai - 400 053 - Dr. Toravi, Jitendra R., M.Tech, Ph.D.,
I.I.T. Bombay, Asst. Engineer,
Sewerage Operation (Planning and Construction),
Municipal Corporation of Greater MumbaiAuthor for Correspondence, E-mail :

Use of drinking quality of water for flushing and taking the sewage away is just a NIMBY(Not In My Back Yard) approach. This has failed to achieve effective sanitation. It is also ruled out where water is in short supply and proper sewerage system is lacking. This is why slums that house about 50% of urban population, are without any proper sanitation facilities. As a result people have to resort to "open air conference" defecation along the roads. Municipal workers that sweep the roads have to carry out the inhuman act of collecting human excreta along with garbage. An odorless self-flushing public toilet was constructed by the Green Cross Society in the premises of Versova Municipal Sewage Pumping Station, in Andheri(W), Mumbai 400 053. Here there is no water connection inside the toilets. People carry 1-2 liters of water for defecation, the thick sewage slurry gets treated in 2 horizontal shallow reactors using the BIOSANITIZER and planted filter. Clean water produced is pumped to the overhead tank that feeds the continuous flushing system. This public toilet has been serving a slum community of about 100 people over the past 8 months. It is a good demonstration of using natural methods of sewage treatment, aimed at producing flushing water in the process. There is no use of electricity for treatment, no production of sludge and CO2. There is no manpower requirement for operation, repairs or maintenance. Operation is without any odor, in fact the toilet has fresh smell of forest air. The toilet pan remains clean due to cleaning properties of the treated sewage. This water also has shown pest-repellent properties. This, effectively, is pest control without using poisons and the resource liquid is produced from human excreta and urine that otherwise can get wasted and pollute the environment.

About half of urban population stays in slums in India and other developing countries. Our toilet system that wastes drinking quality water to flush away human waste, is highly unsuitable for the slums, it is also against the ecological principles of waste minimization and resource recycling. Green Cross Society has been running an official waste management facility for MCGM over the past 10 years. To serve the toilet needs of the operating crew and small slum-like community nearby, a low water use toilet was set up 10 years ago. The accumulated slurry of thick sewage was removed every 2 months by a vacuum truck and sent for disposal. About a year ago, BIOSANITIZER catalyst was added to the system. This reduced the odor immediately, plants of canna were able to flourish in the open horizontal trough that stored sewage slurry. Another section of horizontal planted filter was added for further reefing the water quality and the treated water was collected in a sump and pumped to the overhead water tank that fed the continuous flushing system. The system has been in operation for the past 8 months now and has demonstrated how man and plant ecology can co-exist without producing any worry of odor-pathogens-and-pests. All this is achieved without any water connection to the toilet and there is no sewage flow away from the toilet. In fact, sewage is treated to produce water for flushing. There are no recurring expenses on treatment. There is no use of machinery and electricity, for sewage treatment. There is also no production of sludge and greenhouse gases such as methane or carbon dioxide. In fact, the treated sewage is a resource for ecosanitation. It acts as a plant tonic and its spray also is able to control odor, pathogens and pests. This is an ecological alternative to use of toxic chemicals in the field of agriculture and sanitation. We have to discontinue the use of toxic chemicals because they end up poisoning the whole biosphere. Increasing incidence of cancer in man is linked to widespread use of these carcinogens.

Understanding Sanitation
The chemistry of sanitation was developed during the PhD program of Dr Uday Bhawalkar at the chemical engineering department of IIT Bombay, during 1987-1996(Bhawalkar, 1997). The root cause of all the sanitation challenges such as odor, pathogens and pests happens to be the nitrates (and other inorganics that can become nitrates, such as urea, ammonia, nitrites, waste proteins, etc.). This is easy to see by carrying out a few simple experiments. If we take substrates like milk, honey and cheese and vary the substrate to nitrate ratio by putting variable quantity of calcium nitrate solution, we see that odor-pathogens-and-pests come according to different nitrate levels. Visible pests are attracted at low nitrates, then comes the odor band. At highest nitrate level one gets into the pathogen band.

Plants need nitrates for their nutrition. Human wastes are plant food(fertilizer). This is obvious from the fact that farmers use urea and we excrete urea/uric acid and carbohydrates along with waste proteins and nitrates. If human wastes are used for plant growth, we are completing the cycle of nature. This is called ecosanitation (Bhawalkar, 2005).

BIOSANITIZER granules convert polluted water into clean water, which also becomes a resource for ecosanitation. This action can be summarized as follows (Bhawalkar, 1997):

Sanitation problems arise due to nitrates, hence nitrate management is crucial. Conventional nitrate management techniques consume organic food and oxygen, to produce CO 2 and waste heat. Nature prefers another reaction, i.e., combining nitrates, CO 2 and waste heat to produce organics and oxygen. This is a resource-generating mechanism, while conventional denitrification is a wasteful reaction. BIOSANITIZER is a natural catalyst; 1 gram of this product has the capacity of 1 acre of rich forest, in terms of its nitrate control, CO2 trapping and oxygen production.

By adding BIOSANITIZER in a stream of polluted water, we get not only clean water, but the treated water also becomes a resource for ecosanitation.

BIOSANITIZER has been used successfully in several field-scale projects involving cleaning of ponds, lakes, flowing sewage nallas, polluted rivers and even the polluted groundwater. BIOSANITIZER is used at the source of pollution. The granules have a long life because they work without getting depleted. They operate on diverse aspects of water pollution, such as, odor, pathogens, pests, chemical toxicity and also the inorganic toxicity. The pollution is not separated and thrown elsewhere, this would be a NIMBY affair. Instead, the pollution is converted into resources using the time-tested principles of nature.

Details of the Public Toilet
For serving a community of 100 people, there are 2 toilets with standard superstructure. There is no water connection, but the flush operates all the time the pump is run. A 1/4 HP pump is used to pump the treated sewage to the 500 liters size overhead water tank, this feeds the self-flushing system that keeps the toilet clean and odor-free without a water connection. People take only 1-2 liters of water for defecation. The sewage treatment is in two stages. First tank is open, has canna plantation without any filter medium. The second stage is horizontal flow planted filter on gravel medium. BIOSANITIZER is added through the toilet when the system is started. One can see natural sewage treatment without any odor-pathogens-pests fear. In fact, one only sees a healthy garden behind the toilet.

Resource Production
BIOSANITIZER converts polluted water into safe, hygienic oxygen-rich water. This has been found to be a resource for ecosanitation. Its spray (or soil application) boosts the plant growth because of its enzymes that regulate the nitrates to the plants' need. The spray also has been found effective against odor, pathogens and pests. This, too, is achieved through the nitrate-regulating enzymes produced through the BIOSANITIZER action. Resource value of the treated sewage, thus, is about Rs 300/- per liter. This is the price at which other similar biotech-products are available in the market. There is a need to evaluate all such non-toxic options of achieving ecosanitation. Conclusion
Ecosanitation using BIOSANITIZER is more than just cleaning pollution; it turns pollution into resources. It conserves the good components of waste streams, converts harmful ones into useful ones, and produced a resource using the nature's principles that have evolved on this earth over millennia. The author strongly recommends discontinuing the use of resource-guzzling treatment technologies of the past and use ecosanitation techniques that convert all negatives into positives. BIOSANITIZER is one such solution.

1. Bhawalkar, U.S.(1997)Vermiculture Bioconversion of Organic Residues, PhD thesis, Chemical Engineering Department, IIT Bombay, Mumbai.
2. Bhawalkar, U.S. and Bhawalkar, S. U.(2005)BIOSANITIZER: A Resource for Ecosanitation, 9 th International Ecosan Conference, 25-26 November, 2005, Mumbai








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