Background Treating latex rubber sheet wastewater often leads to the generation of a rotten-egg odor from toxic H2S. To increase the treatment efficiency and eliminate H2S, purple nonsulfur bacteria (PNSB), prepared by supplementing non-sterile rubber sheet wastewater (RAW) with fermented pineapple extract (FPE), were used to treat this wastewater under microaerobic light conditions. The following 3 independent variables: chemical oxygen demand (COD), initial pH and FPE dose were investigated using the Box-Behnken design to find optimal conditions for stimulating the growth of indigenous PNSB (PNSBsi). Results The addition of 2.0% FPE into RAW, which had a COD of 2000 mg L- 1 and an initial pH of 7.0, significantly decreased oxidation reduction potential... |