Sewage sludge: a review of business models for resource recovery and reuse

In many low- and middle-income countries, sewage sludge generated from wastewater treatment systems has potential environmental and health hazards. To tackle this challenge, there is a need for innovative options given the increasing concerns and policies restricting sewage sludge dumping in landfills and elsewhere, and a growing awareness about the resource value of sludge within a circular economy. In developed countries, water utilities, municipalities and the private sector are increasingly engaged in utilizing and innovating modern resource recovery technologies to capture biosolids, nutrients or energy from sewage sludge and reducing disposal. This study reviews existing approaches and business models for resource recovery and moves the discussion beyond technical feasibility. Case studies were analyzed in support of four main sets of business models depending on the targeted resource: (i) organic fertilizers, (ii) crop nutrients, (iii) energy, and (iv) organic fertilizers and nutrients along with energy.