Biodegradation of cresyl diphenyl phosphate in anaerobic activated sludge: Degradation characteristics, microbial community succession, and toxicity assessment

Cresyl diphenyl phosphate (CDP), an emerging aryl organophosphate ester (OPE), exhibits potential toxic effects and is frequently found in diverse environmental media, thereby raising concerns about environmental pollution. Biodegradation demonstrates substantial potential for CDP removal from the environment. This study investigated the biodegradation mechanisms of CDP using anaerobic activated sludge (AnAS). The biodegradation of 1-mg/L CDP followed a first-order kinetic model with a degradation kinetic constant of 0.943 d⁻¹, and the addition of different electron acceptors affected the degradation rate. High-resolution mass spectrometry identified seven transformation products (TPs) of CDP. The pathways of CDP degradation in anaerobic conditions were proposed, with carboxylation products being the most dominant intermediate products. The structure of the anaerobic microbial community at different degradation time points in CDP-amended microcosms was examined. The linear discriminant analysis (LDA) of effect size (LEfSe) potentially underscored the pivotal role of Methyloversatilis in CDP biodegradation. Zebrafish embryotoxicity experiments revealed both lethal and morphogenetic impacts of CDP on zebrafish embryos. The survival rate, hatching rate, and body length indicators of zebrafish embryos underscored the detoxification of CDP and its resultant intermediates by AnAS. This study offers new insights into the fate and biodegradation mechanisms of CDP in wastewater treatment plants.