Elaboration of an algae‐to‐energy system and recovery of water and nutrients from municipal sewage

Increasing pressure is being exerted on the peri‐urban space that has elevated the demand for electricity, affects the global water resource, and impacts the potential to produce food, fiber, and commodity products. Algae‐based technologies and in particular algae‐based sewage treatment provides an opportunity for recovery of water for recycle and re‐use, sequestration of greenhouse gases, and generation of biomass. Successful coupling of municipal sewage treatment to an algae‐to‐energy facility depends largely on location, solar irradiance, and temperature to achieve meaningful value recovery. In this paper, an algae‐to‐energy sewage treatment system for implementation in southern Africa is elaborated. Using results from the continued operation of an integrated algal pond system (IAPS), it is shown that this 500‐person equivalent system generates 75 kL per day water for recycle and re‐use and, ∼9 kg per day biomass that can be converted to methane with a net energy yield of ∼150 MJ per day, and ∼0.5 kL per day of high nitrogen‐containing liquid effluent (>1 g/L) with potential for use as organic fertilizer. It is this opportunity that IAPS‐based algae‐to‐energy sewage treatment provides for meaningful energy and co‐product recovery within the peri‐urban space and, which can alleviate pressure on an already strained water–energy–food nexus.