Design of an intensified system for treatment of faecal sludge from unplanned settlements in the cities of Malawi

Abstract

A significant proportion of human excreta emptied from onsite sanitation systems - mostly pit latrines - ends up disposed untreated or partially treated in the urban environment of many developing countries. This poses threat to the health of human beings and integrity of the environmental in the general urban setting. The situation is attributed to lack of appropriate treatment infrastructure; traffic congestion, long distances and high transportation costs to existing centralised conventional wastewater treatment facilities. Decentralised faecal sludge treatment systems (DEFASTS) centred around decentralisation (having smaller units spread across the urban areas), simplicity (reliance on natural processes in place of chemical and energy input) and reuse of treatment products presents one option that has potential to address these challenges. However, in urban areas of most developing countries there is limited availability of land to treat the human excreta closer to unplanned settlement where most of the faecal sludge is mostly generated. In addition, there are concerns over the negative public health impacts of having these treatment closer to settlements. In our study we developed a treatment system that reduces the time and land space requirement to treat the human excreta to levels that can be easily handled and pose no public health threat for reuse in agriculture.