Poultry slaughterhouse wastewater treatment using a static granular bed reactor (Sgbr) coupled with a hybrid sidestream membrane bioreactor

Abstract

An increase in the demand for poultry products coupled with the potable water shortages currently experienced in South Africa (SA), attributed to climate change among other factors, makes it crucial for SA to develop water conservation strategies to minimize potable water consumption by water-intensive industries, such as the poultry industry. The development of innovative wastewater treatment processes is therefore paramount in attempting to counteract the large quantity of wastewater generated as well as to manage the environmental health concerns arising from poultry slaughterhouse wastewater (PSW) discharge into the environment. Moreover, increasing wastewater treatment costs and the implementation of increasingly stringent government legislation to mitigate environmental pollution whilst minimizing fresh water source contamination, requires that wastewater such as PSW, be adequately treated prior to discharge. This study, investigated the feasibility of treating PSW from a poultry slaughterhouse to: 1) a water quality standard compliant with industrial wastewater discharge standards and 2) for possible re-use purposes. The performance of a lab-scale PSW treatment system consisting of an anaerobic static granular bed reactor (SGBR) followed by single stage nitrificationdenitrification (SSND) bioreactor and sidestream ultrafiltration membrane module (ufMM) post-treatment systems, were evaluated, with the objective being to: assess the treatment efficiency of the individual treatment systems namely; the SGBR, SSND bioreactor, and ufMM, under varying operational conditions, as well as to determine the performance of the overall designed PSW treatment system. The down-flow SGBR (2 L) was used to reduce the organic matter (COD, BOD5, and FOG) and total suspended solids (TSS) in the PSW. Anaerobic granules from a full-scale mesophilic anaerobic reactor treating brewery wastewater were used to inoculate the SGBR, and the PSW used as feed was obtained from a local poultry slaughterhouse (Western Cape, South Africa). The SGBR was operated continuously at mesophilic temperature (35-37 °C) without pH modification and under varying HRTs (24, 36, 48, 55, and 96 h) and OLRs (0.73 to 12.49 g COD/Lday), for a period of 138 days. The optimization of the SGBR, with regard to a suitable HRT and OLR, was determined using response surface methodology (RSM) and Design Expert® 10.0.3 statistical software. Periodic backwashing of the SGBR system was performed using stored effluent, i.e. treated PSW.