Several geographic regions have been exposed by the new study as major hotspots for unsafe wastewater reuse in agriculture, raising a red flag for public health in these places. In India, for example, 8.9 mega hectares of land are irrigated downstream of cities with a high likelihood of untreated wastewater - this account for about 15 percent of India’s irrigated land. Research shows more than 80 percent of the pathogenic pollution of surface water in India has been attributed to the approximately 100 million septic tanks and 60 million latrines in urban areas, which are poorly maintained, and lack treatment facilities for the captured excreta. This results in human waste continuously finding its way into water bodies and potentially the food system.
It is clear we must step up our response to this problem, in order to reduce the risks, particularly for the poor. We recommend a dual line of response.
Reducing the risks of wastewater use for farmers and consumers in the short term requires a ‘multi-barrier’ approach, as recommended by the World Health Organization (WHO) - especially for situations where we cannot yet rely on comprehensive wastewater collection and treatment. This approach consists of a series of actions that fight contamination along the entire food chain. These include wastewater treatment (if available), but focus strongly on safe irrigation, as well as hygienic food handling and preparation. These on-farm and post-harvest actions can jointly reduce the disease burden by 70 percent, if only three out of four farmers, traders and households adopt the recommended practices.
Sadly, behaviour change needs time. This is due to a number of reasons - from lack of consumer awareness about the health threat to farmers’ limited (financial) incentives to change their practices, as well as low institutional capacities to support regulations.
Yet there also exists an opportunity to turn the entire wastewater challenge on its head - and to see this abundant resource as an asset instead of a threat. This involves focusing on the vast number of septic tanks and pit latrines which capture around 90 percent of wastewater in many low- and middle-income countries. With the right investments, the collected faecal sludge can provide us with valuable by-products, from fertiliser to power. It is estimated that the global wastewater supply could generate enough energy to provide electricity from biogas for about 130 million households. And where biogas technology faces challenges, the sludge can be easily dried and pressed into briquettes, a practice increasingly seen in East Africa. If businesses can tap into this opportunity, then overflowing septic tanks will become history and the costs of excreta treatment could be recovered through the sale of valuable products. This will provide the necessary incentives to catalyse sustainable wastewater management beyond the provision of toilets.
In Ghana, this step change is taking shape. A recently launched co-composting plant in Greater Accra will produce and market 500 tonnes of a new organic fertiliser named, Fortifer, annually, by treating 12,500 cubic metres of human waste, and 700 tonnes of other organic waste. It is a safe, odourless, nutrient-rich compost, which the plant will sell in powder and pellet forms to improve the yields of common grains, like maize and rice, as well as any other crops. Fortifer received governmental approval and will not only bring incentives into the sanitation service chain, but also combat poor soil health which remains a major barrier to farm productivity and food security in Africa.
This article has been excerpted from the article: ‘Is your food
watered by waste?’