No abstract

Due to the increasing use of antibiotics, tetracycline was frequently detected in wastewater. As a novel technology, algal‐bacterial granular sludge process is expected to be widely used in wastewater treatment. However, the degradation effect of tetracycline by algal‐bacterial granular sludge process and its degradation path is still unknown. In this study, mature and stable algal‐bacterial granular sludge was cultured and the degradation of tetracycline by it was investigated. The results showed that the removal amount of 1–25 mg/L tetracycline by algal‐bacterial granular sludge was 0.09–1.45 mg/g volatile suspended solids (VSS), in which the adsorption amount was 0.06–0.17 mg/g VSS and the degradation amount was 0.03–1.27 mg/g VSS. Tetracycline biosorption was dominant at its concentration of 1–3 mg/L, while biodegradation was predominant at 5–25 mg/L of tetracycline. At tetracycline concentration of 3–5 mg/L, the contribution of biosorption and biodegradation to tetracycline removal by algal‐bacterial granular sludge process was almost equal. Algal‐bacterial granular sludge could effectively degrade tetracycline through demethylation, dehydrogenation, deacylation, and deamination or their combination. In addition, the degradation products were nontoxic and hardly pose a threat to environmental health. The research results of this paper provide a solid theoretical basis for tetracycline removal by algal‐bacterial granular sludge and a reference for the development of algal‐bacterial granular sludge process for wastewater treatment in the presence of tetracycline. Practitioner points Mature and stable algal‐bacterial granular sludge was cultured. Tetracycline was removed by algal‐bacterial granular sludge through biosorption and biodegradation. Algal‐bacterial granular sludge could degrade tetracycline through demethylation, dehydrogenation, deacylation, and deamination or their combination. The degradation products were nontoxic.