Influence of agitation rate on the performance of a stirred anaerobic sequencing batch reactor containing immobilized biomass

The present work reports on the influence of the mechanical agitation rates on the performance of a stirred anaerobic sequencing batch reactor contain ing immobilized biomass on polyurethane foam, as inert support, treating sy nthetic domestic wastewater. The reactor was operated at 30 degreesC and an 8-hour cycle was used to treat approximately 0.5 L of the synthetic substr ate with a COD concentration of nearly 500 mg/L. The studied agitation rate s ranged from no agitation to 750 rpm. The system attained non-filtered sub strate removal efficiency greater than 83% when agitation was employed. A v ery short start-up period and good solid retention could be observed. The u se of agitation increased the efficiency of the reactor and enabled reducti on of the total cycle time. An empirical equation and a first-order kinetic model are proposed to analyze the influence of agitation rates on the reac tor's performance.