Opportunities for circular bionutrient economy in Kenya: Sanitation and waste stream characterization

Abstract

The majority of people in low-and middle-income countries, such as Kenya, lack effective sanitation and waste management systems. Circular bionutrient economy (CBE) is emerging as a framework to safely reuse organic wastes in agriculture. This study aimed to characterize waste and sanitation systems in Kisumu City, Kenya, with a view to exploring opportunities for CBE in the Lake Victoria basin. Sanitation was characterized through a case study approach in a populous informal settlement, and waste was quantified in two markets in the city. The main toilet facility was pit latrine, although there were also some urine-diverting dry toilets (UDDTs). One toilet served about 36 people. Over a 1-mo period, the UDDTs yielded approximately 64,400 L of urine, whereas about 67,500 L of fecal sludge was emptied from the pit latrines, out of which only about 33,000 L (48.9%) was properly disposed of. About 3 t of waste was generated daily from the markets, 95% of which was organic, and was disposed of at an open dumpsite. Organic waste, including human excreta, contains large amounts of organic matter and plant nutrients, and can be processed for agricultural nutrient cycles. Additionally, black soldierly larvae can effectively convert organic waste into nutrient-rich fertilizer and high protein biomass for animal feeds. These results suggest an opportunity for a CBE system in the region for sustainable organic waste management and urban sanitation, and with opportunity to improve livelihoods and equity.