Performance evaluation of an integrated multi-stage poultry slaughterhouse wastewater treatment system

Abstract

Poultry slaughterhouse wastewater (PSW) with a high fats, oil, and grease (FOG) content in South Africa (SA) is generally discharged into municipal wastewater systems. This is detrimental for municipal treatment plants since there is a limited number of these wastewater treatment works (WWTWs) that are operating optimally. Furthermore, increasingly stringent standards for effluent discharge have placed an urgency on the development of advanced wastewater treatment technologies. This study evaluated the performance of a lab-scale integrated multi-stage PSW treatment system consisting of an aerobic pre-treatment tank, an expanded granular sludge bed (EGSB) bioreactor coupled with a submerged ultrafiltration (UF) membrane. The possibility of treating PSW to a water quality standard compliant with discharge by-laws or the standards of effluent discharge was investigated. The EGSB was operated for 120 days at a hydraulic retention time (HRT) of 5.71 h and an organic loading rate (OLR) ranging from 200 to 700 mg COD/L⋅h, while the submerged membrane unit had OLR fluctuating between 50 and 450 mg COD/L⋅h. The integrated system achieved overall average removal efficiencies (REs) of 98% for chemical oxygen demand (COD), 97% for FOG, and 99% for total suspended solids (TSS); and reducing the pollutant content of the treated PSW to 101 mg/L COD, 8 mg/L FOG and 7 mg/L TSS, i.e. qualities which are comparable to inland surface water, rendering it safe for discharge into the City of Cape Town (CCT) WWTWs.