An evaluation of single- and separated-phase anaerobic industrial wastewater treatment in fluidized bed reactors

Four fluidized bed reactors were used to evaluate single-and separated-phase anaerobic treatments of a high strength wastewater. Two reactors were fed with a synthetic wastewater, containing glucose as the primary carbon source, with a COD of 1.2 x 10(4) mg/L while the remaining pair were fed with a wastewater with a COD of 6000 mg/L. AT each influent strength, one fluidized bed reactor was operated as a single-phase system while the other was operated as a methanogenic reactor which was preceded by an acidification reactor in a separatedphase system. The reactors were operated under steady-state and variable process conditions. The separated-phase system consistently gave a better quality effluent with lower effluent suspended solids and total COD, and the methane yield was also improved. Under variable process conditions, the separated-phase system was inherently more stable and recovered more rapidly following a shock loading. Propionate and acetate degradation studies indicated that the biomass in the methanogenic fluidized beds of the two-phase systems was more adapted to volatile acid degradation than the biomass in the single-phase fluidized beds.