Treatment of poultry slaughterhouse wastewater using a pretreatment stage, an expanded granular sludge bed reactor coupled with a membrane bioreactor

Abstract

This study presents the biological treatment of poultry slaughterhouse wastewater (PSW) using a combination of a biological pre-treatment stage, an expanded granular sludge bed reactor (EGSB) and a membrane bioreactor (MBR) to treat PSW. This PSW treatment was geared towards reducing the concentration of contaminants present in the wastewater to meet the City of Cape Town (CoCT) discharge standards and evaluating an alternative means of treating medium to high strength wastewater at low cost. The EGSB used in this study was operated under mesophilic conditions and an organic loading rate (OLR) varying between 69 to 456 mgCOD/L.hr. The pre-treatment stage of this pilot plant played a big role in the processing of PSW, with removal percentages varying between 20 to 50% for the total suspended solids (TSS), 20 to 70% for the chemical oxygen demand (COD), and 50 to 83% for the fats oil & grease (FOG). The EGSB further reduced the concentration of these contaminants with removal percentages varying between 25 to 90% for the TSS, 20 to 80% for the COD, and 20 to >95% for the FOG. The last stage of this process, the MBR, contributed to a further decrease of the concentration of these contaminants with a peak performance of >95% for the TSS and COD removal percentages, and 80% for the FOG. Overall, the system (pretreatment-EGSB-MBR) exceeded the performance of 97% removal for the TSS and COD and a peak performance of 97.5% for the FOG removal. The results culminated in an effluent meeting the City of Cape Town municipal discharge standards.