Operational performance of an anaerobic-anoxic-aerobic treatment system

Abstract

An anaerobic (UASB) - hybrid aerobic (suspended and attached growth activated sludge) wastewater treatment system was evaluated on the removal of organic matter, solids and nitrogen following its pre-operational phase. Analysis were made weekly based on composite sample, prepared by grab samples taken every four hours, during 24-hour cycle, weighted by flow rate, on each monitoring point (raw, sewage, UASB, anoxic chamber, aerobic reactors, return sludge form secondary decanters and final effluent). The plant presented an average flow rate of 908 m3/h with peaks from 10 to 14 h. BOD was removed by 86% (310 to 41 mg/L) being the highest parcel accounted by UASB reactors (70%) and removal of total suspended solids reached 63% (190 to 94 mg/L). Means removals of TKN (71%) and Ammonium (77%) were above the value predicted by design and, probably the nitrification-denitrification process was not the dominant route.