Performance of an expanded granular sludge bed (EGSB) reactor coupled with anoxic and aerobic bioreactors for treating poultry slaughterhouse wastewater

Generally, slaughterhouses have the largest consumption of fresh water and thus generate large quantities of high strength wastewater, which can be treated successfully using low cost biological treatment processes. In this study, the feasibility of using an expanded granular sludge bed (EGSB) anaerobic reactor coupled with anoxic and aerobic bioreactors for the treatment of poultry slaughterhouse wastewater was investigated. The poultry slaughterhouse was characterized by high chemical oxygen demand (COD), 2 to 6 g/L, with average biological oxygen demand of 2.4 g/L and average fats, oil and grease (FOG) being 0.55 g/L. A continuous EGSB anaerobic reactor was operated for 26 days at different hydraulic retention times (HRT), i.e. 7, 4, 3 days, and organic loading rates (OLR) of 0.5, 0.7 and 1.0 g COD/L.day, respectively, to assess the bioremediation of the poultry slaughterhouse wastewater. The average COD removal from the EGSB was 40%, 57% and 55% at the different OLR and HRT assessed. At high OLR of 1.0 g COD/L.day, the overall COD removal from the system (EGSB-anoxic/aerobic) averaged 65%. The system experienced periodical sludge washout during high FOG and suspended solids loading. It was concluded that the EGSB system requires a dissolved air flotation system, for FOG/suspended solid reduction, as the performance of the overall system was observed to deteriorate over time due to the presence of a high quantity of FOG including suspended solids.