Integration of Biological Biogas Scrubbing System for Treatment of High Sulfate Wastewater Using AnMBR Technology: From Piloting to Full-Scale System

Pilot and full-scale anaerobic membrane bioreactor (AnMBR) wastewater treatment systems were installed and operated at a biodiesel refining plant in Missouri. The biodiesel production wastewater contains high concentrations of chemical oxygen demand (COD, average value of 49,400 mg/l), biochemical oxygen demand (BOD), fats, oils, and greases (FOG, average value of 2,200 mg/l), and sulfate (average value of 4,600 mg/l). The pilot study was used to evaluate the feasibility of anaerobically treating the high-strength industrial wastewater. Sulfide toxicity on the anaerobic bacteria, posed by the high influent sulfate concentration, was prevented in the pilot-scale system by integrating a biogas scrubbing system into the biogas recirculation system. This concept was applied to the full-scale system and the full-scale system has been able to effectively treat the wastewater, maintaining average COD, FOG, and total suspended solids (TSS) removal efficiencies greater than 96%. The full-scale system features an 8,100 m3 (2.15 MG) bolted steel tank with floating geomembrane cover system, two concrete, sealed membrane tanks, a sulfur oxidation (SO) tank, and a biological biogas scrubbing system. The membrane modules are Kubota flat-sheet membranes composed of chlorinated polyethylene with a nominal pore size of 0.2 μm.