The performance of co-immobilized strains isolated from activated sludge combined with Scenedesmus quadricauda to remove nutrients and organics in black odorous water

[Display omitted] •Three heterotrophic nitrification-aerobic denitrification strains were isolated.•The immobilization was constructed in combination with Scenedesmus quadricauda.•The optimum conditions of black odorous water treatment were obtained by RSM.•The immobilized microalgae-bacteria greatly removed pollutants.•The immobilized microalgae-bacteria had excellent stability and reusability. In this study, three bacteria were isolated from activated sludge (Pseudomonas aeruginosa, Bacillus subtilis, and Dietzia maris). After that, isolated strains and Scenedesmus quadricauda that could degrade refractory organics, as co-immobilization species, were prepared gel beads to treat black odorous water. Under the optimized conditions, the removal rate of chemical oxygen demand (COD), ammonia nitrogen (NH3-N), total nitrogen (TN) and total phosphorus (TP) reached 94.36%, 95.7%, 91.22% and 95.27%, respectively, and organics (including aromatic proteins and microbial-by-product-like compounds) were also significantly removed. Microbial analysis reveals that the community structure had a significant difference before and after treatment, and the main dominant at the genus level was transformed from Nitrospirillum (approximately 18.03%) to Flavobacterium (approximately 17.64%). This study also found that the immobilized gel beads have excellent stability and reusability, which provided a feasible and robust bioremediation strategy for the treatment of actual black-odor water.