Differentiation and Quantification of Linear Alkylbenzenesulfonates Removal by Microalgae and Bacteria in the Symbiotic Culture: Kinetics and Mechanisms

While the microalgal–bacteria synergistic system enabled efficient linear alkylbenzenesulfonate (LAS) mineralization during greywater treatment, the individual contribution of microalgae and bacteria in LAS removal remains undefined. This work explored LAS removal kinetics and mechanisms by quantitative differentiation of adsorptive and biodegradative processes mediated by microalgae and bacteria in the mixed culture. During the initial stage (0–2 h), soluble LAS was rapidly adsorbed onto both microalgae and bacteria. Microalgae exhibited higher LAS uptake capacity, attributed to abundant binding sites from –COOH, –SH, –CONH2, and phosphorus-containing groups, whereas bacteria displayed a higher LAS uptake constant and shorter adsorption equilibrium time owing to their smaller cell size and greater surface area. Bacterial driven LAS biodegradation sustained efficient mineralization, with living microalgae enhancing bacterial LAS mineralization capacity through oxygen supply and CO2 utilization. In the symbiotic system, microalgal and bacterial adsorption accounted for 42.4% and 39.5% of LAS removal, respectively, while bacterial biodegradation contributed 18.1% after 2 h. These findings offer novel mechanistic insights into microalgae–bacteria synergism for recalcitrant pollutants removal, establishing a robust theoretical basis for optimizing microalgal–bacteria biofilm in greywater treatment.