Abstract
An increase in water demand due to population growth increases the quantity of wastewater generated. If left untreated, wastewater contains harmful compounds and pathogens that threaten human health and the environment. Assessing a wastewater treatment plant’s performance and effective removal of pollutants is critical in informing operational decision-making and plant optimisation. This study aimed to investigate the reliability of pollutant removal in Gqeberha’s wastewater treatment plant using secondary effluent data from 2018 to 2022. The pollutant determinants considered included chemical oxygen demand (COD), suspended solids (SS), nitrate or nitrite as nitrogen, ammonia as nitrogen, and orthophosphate as phosphorus.
The probability-based approach is adopted in the reliability evaluation, ensuring that the factors affecting variation in wastewater are considered. Optimisation measures that can be employed to improve the wastewater treatment plant’s performance are also recommended. The results indicated a considerable variability in wastewater. Moreover, the results indicated that the case study wastewater treatment plant had a low to moderate performance in removing COD and SS. The removal of nitrate or nitrite as nitrogen and orthophosphate as phosphorus was satisfactory. However, the plant performed poorly in removing ammonia as nitrogen. The aeration tanks and secondary clarifiers must be assessed and optimised to improve secondary treatment performance and ensure that high-quality effluent is achieved.