Abstract
Microalgae-based technology is an environmentally friendly and cost-effective method for wastewater treatment. This study investigated the microalgal biofilm formation and nutrient removal in a revolving algal biofilm (RAB) system for treating raw aquaculture wastewater. Comparative analysis demonstrated that a novel constructed co-culture of Chlorella vulgaris and a newly isolated Synechocystis sp. in RAB outperformed both the monocultures and the native microalgae-bacteria consortium. Under a continuous operational mode at 3-day of hydraulic retention time (HRT) without prior pretreatment, the co-culture biofilm achieved the highest biomass production (3.58 g/m2), EPS content (165.8 mg/g) and near-complete removal of total nitrogen (99.0%) and phosphorus (98.7%) from the raw aquaculture wastewater. Microbial community analysis indicated the significant synergistic interactions between the microalgae (C. vulgaris and Synechocystis sp.) and bacteria (primarily Proteobacteria), which facilitated the formation and stabilization of algal biofilm and nutrient removal. This study provides critical insights into the mechanism of biofilm formation within RAB systems and their potential for treating raw aquaculture wastewater.