## 5 Conclusions  
The study of the lab-scale plant of the biological pre-treatment of the PSW coupled with the DEGBR was successfully employed. At the pre-treatment stage, the FOG, COD and TSS removal efficiencies that were obtained were 80 \(\pm\) 6.3%, 38 \(\pm\) 8.4%, and 56 \(\pm\) 7.2%, respectively. Similarly, the DEGBR achieved average FOG, COD and TSS removal efficiencies of 89 \(\pm\) 2.8%, 87 \(\pm\) 9.5% COD and 94 \(\pm\) 3.7%, even at high OLR of up to 8.3538 g COD/L day with an HRT of 106 h. Moreover, the overall performance of the conjoint systems achieved a FOG, COD and TSS efficiency of 97 \(\pm\) 0.8%, 92 \(\pm\) 6.3% and 97 \(\pm\) 1.2%, respectively. The DEGBR system was operating under stabilized conditions since the pH was within the optimal range of 6.6-8 and the VFA/alkalinity ratio was consistently around 0.2, albeit slightly lower than the recommended 0.3 throughout the experimental period. The average methane gas production reported during the start-up period was 0.3 L CH\({}_{4}\)/g. COD, which reduced as the operation ensued. This was attributed to the application of EcolflushTM containing pre-treated wastewater feed to the DEGBR. A full-scale application of the DEGBR to treat similar high-strength wastewater treatment would provide benefits to \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **CCT* by-Law Limits** & **EHS* & **DEGBR Product** \\ \hline COD & 5000 mg/L & 250 mg/L & 669 mg/L \\ \hline TSS & 1000 mg/L & 50 mg/L & 185 mg/L \\ \hline FOG & 400 mg/L & 10 mg/L & 28 mg/L \\ \hline pH & 5.5-12 & 6–9 & 7.3 \\ \hline Temperature & 0–40 \({}^{\circ}\)C & \textless{3} \({}^{\text{a}}\) & 37.5 \({}^{\circ}\)C \\ \hline VFA & - & - & 157.97 mg/L \\ \hline Alkalinity & - & - & 888.12 mg/L \\ \hline \hline \end{tabular}  
* CCT*–City of Cape Town: Wastewater and industrial effluent by-law, 2013. EHS*—environmental, health, and safety guidelines poultry production, world bank group, 2007. \({}^{\text{a}}\) At the edge of a scientifically established mixing zone which takes into account ambient water quality, receiving water use, potential receptors and assimilative capacity.  
\end{table} 
Table 4: DEGBR’s product in comparison to City of Cape Town’s specifications and others. Figure 18: A comparison of raw PSW effluent and DEGBR product sample. the slaughterhouse wastewater treatment plants, due to its simple design and operational advantages over conventional high rate anaerobic systems. Lastly, the designed lab-scale plant can be used in small and large poultry processing industries. [PERSON] is the author of the draft manuscript and was responsible for sample analysis, and initial data interpretation. [PERSON] checked the collated data, reanalyzed, reinterpreted the data and assisted in data presentation. [PERSON] and [PERSON] conceptualized the study, revised the manuscript and analyzed the data. E.K. designed and built the lab-scale plant under Malutsa Pty Ltd., Western Cape, Wellington Industrial Park, SA. All authors have read and agreed to the published version of the manuscript. This study was funded by National Research Foundation of South Africa, Thuthuka Funding, R017. Furthermore, the Cape Peninsula University of technology (URF, cost centre: R641 and the Bioresource Engineering Research Group, BioERG)) contributed additional funding for the study. The data will be hosted on Digital Knowledge (CPUT repository) for compliance with the National Research Foundation (Funder) Statement on research data. The CPUT data storage is accessible at [[https://esango.cput.ac.za/articles/dataset/Pre-treatment_and_DEGBR_data_for_poultry_slaughterhouse_wastewater/14910072/1](https://esango.cput.ac.za/articles/dataset/Pre-treatment_and_DEGBR_data_for_poultry_slaughterhouse_wastewater/14910072/1)]([https://esango.cput.ac.za/articles/dataset/Pre-treatment_and_DEGBR_data_for_poultry_slaughterhouse_wastewater/14910072/1](https://esango.cput.ac.za/articles/dataset/Pre-treatment_and_DEGBR_data_for_poultry_slaughterhouse_wastewater/14910072/1)).