Aerobic treatment of piggery wastewater with the sequencing batch reactor

Abstract

Laboratory-scale 8-dm3 aerobic sequencing batch reactors (SBR) were used to treat diluted or anaerobically digested piggery wastewaters. Pumps and solenoid air-values were controlled with microprocessor controllers. BOD removals from the two wastewaters were better than 80%. Suspended Solids removal in the SBR treating diluted wastewater was poor. This resulted from the generation of excess biomass in the SBR and the absence of a sludge wasting program. Contrary to this, Suspended Solids removal by the SBR treating anaerobically digested wastewater averaged above 70%. This was contributed to by the characteristics of the MLSS. The dissolved COD of this feed, however, proved difficult to reduce. This was, in part, due to the accumulation of NO2 --N. Although NH4-N removal through nitrification was significant, conversion of NO2 --N to NO3 --N appeared to have been inhibited. Denitrification during 'IDLE' resulted in a decrease in NO3 --N concentrations and an upward correction of mixed liquor pH. © 1987.