Water

All that crap: How can faecal sludge be reused

If more people in India’s rural areas are building septic tanks, there must be effective ways of managing faecal sludge. Here are some ways to utilise it

 
By Sushmita Sengupta
Last Updated: Wednesday 17 April 2019
Photo: Getty Images
Photo: Getty Images Photo: Getty Images

The latest data on rural sanitation from the Union Ministry of Drinking Water and Sanitation (MDWS) has said that more than 99 per cent of India’s rural households have been covered by toilets.

The National Annual Rural Sanitation Survey of 2018-19 points out that around 38 per cent of the toilets are attached to some kind of septic tank. Officials from MDWS say the septic tank is the most popular option for people, who have a tendency to move towards it as an option for on-site sanitation.

This raises a concern — what will happen to the huge of amount of faecal sludge sucked out of these tanks?

Subhash Kirpal, a resident of Linga gram panchayat of Nagpur district in Maharashtra says communities that are well-off prefer septic tanks. In Uttar Pradesh’s Kannauj district, the toilets in the Umrada block constructed under the Swachh Bharat Mission are attached to box-like containment structures wrongly termed as “septic tanks”.

Kirpal explains that faecal sludge in the septic tank (or the box in some cases) is emptied by honey suckers and dumped in agricultural fields. The villagers struggle with the raw faecal sludge in the fields. There have been studies to show that that dry faecal sludge can be mixed with organic wastes and used for crop production successfully. Countries like India and Bangladesh have implemented some of these projects.

According to Olufunke Cofie, International Water Management Institute, Africa Regional Office, Ghana, inorganic fertiliser is not sufficient to add nutrients to the soil for crop production. Cofie says that excreta contains valuable nutrients like nitrogen, phosphorous, potassium and organic matter. Municipal solid wastes (MSW), which are also dumped without planning, contain phosphorous, nitrogen, phosphorous, potassium and carbon. Co-composting of faecal sludge and MSW complement each other and provide missing components to each other as per Cofie. The microbial population in the final product is reduced enormously says a 2009 study by Cofie. The study says that the final product complies with the 2006 standards of the World Health Organization for the safe reuse of faecal sludge. 

A study published in 2017 in the International Journal of Recycling of Organcic Waste in Agriculture shows that de-watered faecal sludge mixed with agricultural wastes like oil palm, empty fruit bunches or cocoa pod husks is a good fertilisers. An experiment had been carried out at the University of Ghana at the Forest and Horticultural Crops Research Centre. 

The researchers point out that Ghana produces around 3.5 million tonnes of human excreta based on the average production of 400 grams per capita per day. Similarly, the country also produces 3,135,000 tonnes of empty fruit bunches and 550,750 tonnes of dry cocoa husks. This leaves a lot of human and agricultural wastes in the environment, which are dumped in landfills. According to the authors, co-composting of dried faecal sludge and agricultural wastes can be used as an alternative option for managing these wastes and to produce a suitable soil amendment.

The Rural Development Organisation Trust, a Tamil Nadu-based non-profit that has been working in the Nilgiris since 1980, has put up three faecal sludge treatment plants (FSTP). The compost from here is blended with kitchen waste compost. About two tonnes of co-compost is produced every day, says Raj Kumar, the Chief Executive Officer of the plant.

Kumar explains the Ketty Town Panchayat in the Nilgiris has developed a FSTP a year-and-a-half ago. There are 68 villages here, with 40 to 50 households in each village. The toilets are either connected to leach pits or septic tanks. The tanks are emptied by honey suckers and brought to the plant.

The Town Panchayat has a resource recovery park and the FSTP has been developed as a part of this. The manure is tested at a laboratory in Chennai every month before being distributed to farmers at a subsidised price of Rs 5 per kilogram. The revenue is collected by the Town Panchayat. According to Kumar, the cost of the FSTP comes to Rs 50,000 per kilolitres per day. 

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