Optimizing performance efficiency of algal-bacterial-based wastewater treatment system using response surface methodology

Developing wastewater treatment technologies is crucial for enhancing treatment efficiency and promoting the reuse of treated water. In this article, the Algal-Bacterial integrated system (ABIS) is employed to treat municipal wastewater collected from the Zenin wastewater treatment plant in Giza governorate, Egypt. This system relies on the synergy between heterotrophic bacteria and microalgae to form a biofilm capable of absorbing contaminants from the wastewater. The main objective of this study is to optimize the factors influencing the treatment efficiency using response surface methodology derived from the experimental design software of Design Expert 6.0.8. The optimal results revealed that using an absorber amount of 0.18 g/L for a hydraulic retention time of 1.4 d provides removal efficiency of BOD, COD, TSS, and turbidity are 88.57%, 82.7 %, 94.90%, and 95.91%, respectively. These findings were experimentally and statistically verified with an accuracy exceeding a 95% confidence interval and 95% prediction interval. The physicochemical characteristics, algal community structure, as well as the density of total coliform, fecal coliform, and Escherichia coli (E. coli), were determined for the treated wastewater and compared to the Egyptian code of practice for the use of treated municipal wastewater for agricultural purposes to assess its suitability for unrestricted irrigation.