Enhanced degradation of enrofloxacin in mariculture wastewater based on marine bacteria and microbial carrier

This study aimed to isolate marine bacteria to investigate their stress response, inhibition mechanisms, and degradation processes under high-load conditions of salinity and enrofloxacin (ENR). The results demonstrated that marine bacteria exhibited efficient pollutant removal efficiency even under high ENR stress (up to 10 mg/L), with chemical oxygen demand (COD), total phosphorus (TP), total nitrogen (TN) and ENR removal efficiencies reaching approximately 88%, 83%, 61%, and 73%, respectively. The predominant families of marine bacteria were Bacillaceae (50.46%), Alcanivoracaceae (32.30%), and Rhodobacteraceae (13.36%). They responded to ENR removal by altering cell membrane properties, stimulating the activity of xenobiotic-metabolizing enzymes and antioxidant systems, and mitigating ENR stress through the secretion of extracellular polymeric substance (EPS). The marine bacteria exhibited robust adaptability to environmental factors and effective detoxification of ENR, simultaneously removing carbon, nitrogen, phosphorus, and antibiotics from the wastewater. The attapulgite carrier enhanced the bacteria's resistance to the environment. When treating actual mariculture wastewater, the removal efficiencies of COD and TN exceeded 80%, TP removal efficiency exceeded 90%, and ENR removal efficiency approached 100%, significantly higher than reported values in similar salinity reactors. Combining the constructed physical and mathematical models of tolerant bacterial, this study will promote the practical implementation of marine bacterial-based biotechnologies in high-loading saline wastewater treatment.