Performance of a Sequencing Batch Reactor (SBR) in the treatment of domestic sewage

It was studied the biological removal of organic matter and nutrients from domestic wastewater using a Sequential Biological Reactor (SBR) at pilot scale. The study was divided into four phases in which the organic load and the duration of anaerobic, aerobic and anoxic cycle were modified, considering sludge ages of 10 and 7,5 days. During Phases I and II the system was operated with low mass load values: 0,364 and 0,220 kg.COD/kg.VSS.day, while during Phases III and IV were used heavier loads: 0,665 and 0,737 kg.COD/Kg.VSS.day respectively. The results obtained show that the removal efficiencies of organic matter in terms of BOD were achieved during Phase III (91%) and IV (82%) with phosphorus removal exceeding 40%. As for the nitrification process during Phases I and II showed rates of 0,032 and 0,024 kg.N-NH3/kg.VSS. day, this due to lower organic matter content and low BOD/TKN, while during phases III and IV these were lower: 0,015 kg.N-NH3/kg.VSS.day during Phase III and 0,020 kg.N-NH3/kg.VSS.day in Phase IV, however, was in these phases which reached the highest levels of denitrification during the anoxic phase, favored by a C/N appropriate next of 4 kg.BOD/kg.N