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Effect of feed characteristics and operational conditions on treatment of dairy farm wastewater in a coupled anoxic-upflow and aerobic system

Shams, Dilawar Farhan, Singhal, Naresh, Elefsiniotis, Panagiotis
Biochemical engineering journal 2018 v.133 pp. 186-195
biomass production, bioreactors, chemical oxygen demand, dairy farming, denitrification, nitrification, nitrogen, organic matter, sludge, wastewater
This study investigated the removal of nitrogen and organic matter from dairy farm wastewater (DFW) in a hybrid anoxic-upflow bioreactor and aerobic (UBR-A) system. Due to variable and complex composition of real DFW, system performance and behaviour was compared with synthetic wastewater (SWW) in two identical pilot-scale UBR-A systems. Both systems were operated for 334 days first under internal recycle ratios (R) of 2, 3 and 4 and then at solids retention times (SRT) of 140–150, 65–75 and 30–40 days at uniform R of 3. Performance with both wastewaters was comparable with higher nitrification efficiencies (> 90%) and COD removal (>80%) under all conditions, and lower denitrification efficiencies at R > 3. DFW exhibited significantly lower nitrification/denitrification rates, biomass yield, VSS/TSS ratio and a higher inert COD fraction showing that kinetics, sludge characteristics and organic matter degradation were not analogous. The optimum internal recycle ratio was found as R of 3 at a total hydraulic retention time (HRT) of 4 days whereas at different SRTs, performance efficiencies were mostly comparable however nitrification and denitrification rates significantly increased at lower SRT of 30–40 days.