Performance of a biological pre-treatment system coupled with down-flow expanded granular bed reactor (DEGBR) for poultry slaughterhouse wastewater treatment

Abstract

In South Africa, the poultry industry has been identified among the highest producers of wastewater. Generally, Africa and South Africa in particular, has recently faced challenges associated with the availability and access to clean, potable water, with available water sources being contaminated by anthropogenic activities which also has a negative impact on the environment. Therefore, there is a need to invent and design suitable wastewater treatment plants which can be used in the treatment of contaminants found in wastewater. Since poultry slaughterhouse wastewater (PSW) is a one of the major contributors of wastewater generated in South Africa, it is possible that the wastewater produced may pose a threat to aquatic life and it may also lead to water borne diseases if discharged untreated to minimum required standards. Therefore, this creates a need to design efficient and effective PSW treatment processes since the PSW contains a high concentration of chemical oxygen demand (COD), total suspended solids (TSSs), fats, oil and grease (FOG), proteins and carbohydrates. It is important that the wastewater is treated to acceptable environmental discharge standards. This study, evaluated the performance of a biological pre-treatment system coupled with an anaerobic down-flow granular bed reactor (DEGBR) maintained at 37˚C for PSW treatment. The biological pre-treatment system utilizes Eco-flushTM as a FOG hydrolysing agent. The results showed that the biological pre-treatment was observed to be highly effective for removal of FOG, COD and TSS with a removal efficiency of 80±6.3%, 38±8.4% and 56±7.2%, respectively. Similarly, the DEGBR showed a stable performance in terms FOG, COD and TSS removal, with average removal efficiencies of 89±2.8%, 87±9.5%, and 94±3.7%, respectively. The overall removal performance of the integrated system in terms of FOG, COD and TSS, was 97±0.8%, 92±6.3% and 97±1.2%. Furthermore, the average volatile fatty acid/alkalinity (VFA/Alkalinity) ratio of 0.2 was observed, which indicated that the DEGBR was stable throughout the operation. Overall, the biological pre-treatment system coupled with the DEGBR performed satisfactorily with regard to the removal efficiencies of FOG, COD and TSS as compared to other similar systems, i.e. UASB and EGSB.