All the municipal wastewater produced globally each year is enough to irrigate 15 percent of all currently irrigated land, or to power 130 million households through biogas generation, according to a report released by the United Nations last week.
The report, “Sanitation, Wastewater Management and Sustainability: From Waste Disposal to Resource Recovery,” published by the United Nations Environment Programme (UNEP) and the Stockholm Environment Institute (SEI), demonstrates the wide-ranging opportunities for recovery and reuse of the resources found in domestic waste flows.
For example, in Vientiane, the capital city of Laos, enough biogas could be produced from wastewater to allow local buses to travel 10,000 kilometers every day.
A wastewater recycling project in Hölö, Sweden, produces fertilizers and reduces pollution using a combination of infrastructure, patented black water technology, social awareness and certification.
Other innovative ways to reuse wastewater highlighted by the report include using duckweed to clean water in Niger, using sludge as construction filler material in Sweden and a proposal to use the left-over organic waste matter for producing protein feed for livestock through the controlled harvesting of insects.
Municipal wastewater from around the world contains the equivalent of 25 percent of the nitrogen and 15 percent of the phosphorus applied as chemical fertilizers. It can also carry large amounts of iron, chloride, boron, copper and zinc. According to the report, in just one day a city of 10 million people flushes enough nitrogen, phosphorus and potassium to fertilize about 500,000 hectares of agricultural land.
The authors of the report say that a more circular approach to wastewater could bring significant economic and social benefits, while accelerating progress towards the goal of ensuring water and sanitation for all.