Effect of Operational Parameters on Anaerobic Digestion of Municipal and Sugar Industry Wastewater

Received: 26 May 2023. Revised: 16 June 2023. Accepted: 10 August 2023. Available online: 25 September 2023.Anaerobic digestion (AD) is a versatile process that entails low energy consumption and has low capital costs. Unfortunately, this process is not widely commercialized due to instabilities. The instability in the system is due to variations in the feedstock, operating, and environmental conditions. Therefore, this study aimed to determine the effect of organic loading rate (OLR), temperature, and pH on the AD system. An online pH and temperature monitoring sensor calibration were also studied to adjust AD parameters. The water quality parameters that were monitored were turbidity, chemical oxygen demand (COD), and colour. Wastewater with a low and high organic loading had a 90% and 36% COD reduction respectively after 5 days. Without pH adjustment, the pH of the system was 4.1 to 4.4 and the maximum COD reduction was 56.2%. When the pH was increased to 6.8, the maximum COD reduction was 66.5%. For the unadjusted temperature (room temperature), a maximum COD reduction of 56% was achieved. When the temperature was increased to 40℃, the maximum COD reduction was 66%. The increase in pH and temperature resulted in a 10% increase in COD reduction in the AD system. From the study, online pH, and temperature sensor calibrations errors were found to be 0.5 and 0.05 respectively as compared with the manual analytical technique. One of the limitations of this study was obtaining the apparatus to control temperature and pH at the same time. Future research will involve the automation of the AD system will the determined optimum conditions. This suggests smart monitoring and control sensors of AD operational parameters can repurpose its reliability for commercial activity.The authors wish to thank the Durban University of Technology, the Green Engineering Research Group, and the South African Water Research Commission (WRC Project: C2021/2022-00958)