Performance analysis of three pilot‐scale multi‐compartment anaerobic baffled reactors treating domestic wastewater at psychrophilic temperatures in Colorado

A transition from inefficient aerobic wastewater treatment methods to sustainable approaches is needed. Anaerobic bioreactors are a viable solution as they consume less energy, reduce biosolid production, and provide a source of renewable methane‐rich biogas. A barrier to widespread implementation of anaerobic technologies is the lack of design guidance, especially in colder climates. This study bridges this knowledge gap by deriving design principles from three long‐running pilot‐scale anaerobic baffled reactors (ABRs) operating under psychrophilic conditions. The ABRs removed an average of 56% and 80% chemical oxygen demand (COD) and suspended solids, respectively, with a methane yield of 0.21 L CH4/g CODrem. Methane production may be improved with increased influent sCOD concentrations and decreased sulfate concentrations. Results suggest that ABRs can treat a range of wastewater strengths accompanied by useable methane production. Despite sharing location, temperature, and HRT, the ABRs displayed distinct performances, highlighting the significance of influent wastewater characteristics. Practitioner Points ABRs achieved 56% and 80% removal efficiencies for COD and suspended solids. Average biogas was 63% methane, and methane yield was 0.21 L CH4/g CODrem. Volumetric methane production was positively correlated with the influent sCOD/sulfate ratio and negatively correlated with influent sulfate loading. Three pilot‐scale anaerobic baffled reactors treating domestic wastewater at psychrophilic temperatures in Colorado average 56% chemical oxygen demand (COD) and 80% suspended solids removal efficiencies while generating 0.21 L CH4/g CODrem. This performance is enhanced with higher soluble COD and lower sulfate concentrations.