Productive sanitation - the honey suckers of Bengaluru
The dumping of untreated faecal sludge in urban areas has been described as an ecological time bomb. In African cities, typically less than 15 percent of residents are served by centralised sewage systems, and figures for Asian countries are not much better. Yet there is a growing number of examples where re-use of urban faecal waste as fertiliser is linking city households and peri-urban farmers in a chain that provides both affordable sanitation and soil fertility. A recent study* of sanitation services provided in Bengaluru (Bangalore), in southern India, suggests such approaches deserve to be legalised and scaled up within an appropriate legal framework to ensure the safety of farm workers and consumers.
Over 60 per cent of Bengaluru's 8.5 million inhabitants are not connected to a sewage system and rely on other means to deal with their wastewater or faecal sludge. For those that can afford it, this usually means a holding tank or soak pit, often constructed beside the public road, which will be periodically emptied for a fee by a privately operated tanker, known as a honey-sucker. In Bengaluru these generally operate 'extra-legally', not least because the dumping of untreated sludge is prohibited under environmental laws. However, residents certainly value the service and the sanitation entrepreneurs who run it.
While sites for legal disposal of sludge are available, these levy a charge, leading most tanker drivers to dump their cargo elsewhere. Use of human waste as fertiliser is culturally unacceptable for most Indians, but in recent years, tanker drivers have found willing recipients for their sludge among nearby farms. In one instance, researchers even found a tanker driver being paid for the waste. Thus a system of productive waste management has developed in Bengaluru without any form of financial or technical assistance, and numerous small companies have emerged to provide services within this chain.
Productive waste demands safe practices
Typically the sludge is emptied into a large pit, where over a period of around three months it dries. The dried material is then applied to crops, such as coconut palms. Wet sludge is also deposited in trenches, for example between rows of bananas, or applied directly to fallow fields that will be cropped later in the season. Crops produced in these fields include rice, beans, tomatoes and vegetables, the bulk of which are sold to wholesalers. Faecal sludge is typically rich in nitrogen, phosphorous and potassium as well as many micro-nutrients essential to plant health; farmers interviewed for the Bengaluru study reported they earned similar prices to crops fertilised with farmyard manure, while reducing their costs significantly.
None of the farmers interviewed were aware of legal frameworks governing the use of sludge, but some had observed that farm labourers suffered boils on their feet when sludge was applied raw on fields. But for both farmers and consumers, use of untreated sludge on crops poses significant health risks from infectious disease, especially diarrhoeal diseases and intestinal worms. The World Health Organisation recommends a multi-barrier approach for safe use of excreta and household wastewater in agriculture, beginning with separation of solid and liquid wastes and undisturbed storage for at least a year. This is effective in substantially reducing pathogen levels.
At the level of field application, properly stored faecal sludge should be applied close to the ground and incorporated immediately into the soil, avoiding cross-contamination between tools used for treated and untreated material. The WHO recommendations also include hygiene and use of protective equipment by field staff. Crop restrictions include that vegetables eaten raw should not be fertilised even with treated faecal material; a minimum of one month should elapse between application of the material and harvest of crops. A third set of barriers is recommended for consumers, involving food handling and cooking and wider promotion of health and hygiene measures.
Legal frameworks and enforcement
Introducing treatment processes and other health protection systems raises numerous challenges, and would inevitably raise costs for both households using the sanitation service and the farmers. Strong enforcement of appropriate legislation would therefore be important, if safe practices are to be adhered to. However, as the example of Bengaluru illustrates, local authorities lack the resources to enforce existing standards, and to achieve proper regulation in the sector would pose much greater demands. Ideally, a system of certification, with permits for professionals working in the sanitation chain and quality control of the services and products, should be introduced.
For Elisabeth Kvarnström, one of the research team, recognition of the services provided by the honey suckers by the Bengaluru Water Supply and Sewerage Board (BWSSB) is the first priority. Such recognition could lead to funds that might otherwise be invested in extending sewerage networks, being redirected to improving the on-site services provided by tankers and to formalising their business model. Such investment would, Kvarnström suggests, be much more cost effective than sewerage extension. But beyond such funding issues, building trust in the system, including high consumer confidence in the quality and safety of the crops produced, would demand considerable awareness-raising, advocacy and changes in attitude at all levels, both urban and rural.
* The business of the honey suckers in Bengaluru (India): The potentials and limitations of commercial feacal sludge recycling by Verhagen, Kvarnstrom, Nilsson, Sankrathai and Singh
Date published: July 2012
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