Exploring the reuse of high-fat abattoir wastewater through sequential biological treatment in South Africa

This study investigated the performance of a multi-integrated system (MIS) combining advanced biological processes for the treatment of abattoir wastewater (AWW), with a focus on optimizing nutrient removal and mitigating the inhibitory effects of fats, oils, and greases (FOGs). AWW is characterized by high levels of chemical oxygen demand (COD), biochemical oxygen demand (BOD), ammonia, and FOGs, presenting significant environmental challenges when inadequately treated. The research evaluated the treatment efficiency, cost-effectiveness, and potential for on-site water reuse of an MIS, compared to conventional waste management options such as municipal discharge or offsite waste removal. The MIS comprised enzymatic pre-treatment to degrade FOGs, followed by anaerobic digestion (AD) for organic matter removal and methane generation, and a membrane bioreactor (MBR) integrated with activated sludge (AS) for nutrient management. The system employed the Modified Ludzack-Ettinger (MLE) process to enhance nitrogen removal. The treatment achieved removal efficiencies of 98 % for FOGs, 98 % for total suspended solids (TSS), 90 % for COD, 80–90 % for ammonia, and 73 % for E. coli . The AD system utilized a downflow expanded granular bed reactor (DEGBR), operating over 120 days with a hydraulic retention time (HRT) of 3.6 hours and an organic loading rate (OLR) of 12.3 gCOD/L. The findings highlight the potential of the MIS for producing high-quality effluent suitable for on-site reuse while aligning with municipal discharge standards. The study underscores the environmental and economic benefits of integrated biological processes for AWW treatment, resource recovery, and sustainable water reuse, providing a pathway for reducing the environmental footprint of abattoir operations. Future research into nutrient recovery and waste management optimization could further enhance the sustainability of wastewater practices in the abattoir industry.