Demonstration of Anaerobic Digestion of Black Water for Methane Capture and Use in an Office Building

Waste source separation including separate treatment of graywater and black water (BW) is gaining popularity as a sustainable integrated water management practice. Along that line, feasibility of anaerobic digestion of BW (toilet water only) from a building occupied with laboratory and office space was investigated using a pilot scale (114 L) upflow anaerobic sludge blanket (UASB) operated at an average temperature of 28^oC. The goal of the reactor was to achieve removal of organics while also generating methane gas for use as a source of energy. Reactor operational OLR varied between 0.21-0.39 kg COD m⁻³ d⁻¹ and HRT varied from 2.6-4.0 days. Substantial removal of COD (72%), TSS and VSS (95%), and indicator organisms (1.4 log E. coli & 1.1 log fecal coliforms) was achieved over the study period. Methane biogas (61% CH₄) produced during digestion provided potential as a source of renewable energy generated through processing the BW.