Construction of a co-culture system of Bacillus aryabhattai and Desmodesmus sp. and its performance in treating simulated wastewater with high nitrogen and phosphorus

Abstract

The algae-bacteria co-culture system has emerged as a promising approach for biological wastewater treatment. In this symbiotic system, microalgae supply oxygen through photosynthesis, while bacteria reciprocate by providing inorganic and organic nutrients via metabolic processes, enabling synergistic pollutant removal. However, existing studies remain limited in scope, primarily focusing on specific microbial species. In this study, a novel algae-bacteria co-culture system was established using tolerant and dominant algae and bacteria species isolated from a wastewater treatment plant. The growth characteristics and pollutant removal performance of this system were evaluated in simulated wastewater with high nitrogen and phosphorus levels. The results indicated that Bacillus aryabhattai-Desmodesmus sp. (Ba-Ds) co-culture system achieved optimal removal efficiencies for NH₄⁺-N, total phosphorus (TP), and chemical oxygen demand (COD) under conditions of an algae-bacteria inoculate ratio of 5:1, N/P ratio of 6, and pH of 7. The removal rates reached 30.60 %, 49.30 %, and 93.73 %, respectively. These findings highlight the system's enhanced pollutant removal capacity and demonstrate scalable potential for industrial wastewater treatment applications.