Enhanced degradation of triphenyl phosphate (TPHP) in bioelectrochemical systems: Kinetics, pathway and degradation mechanisms

Triphenyl phosphate (TPHP) is one of the major organophosphate esters (OPEs) with increasing consumption. Considering its largely distribution and high toxicity in aquatic environment, it is important to explore an efficient treatment for TPHP. This study aimed to investigate the accelerated degradation of TPHP in a three-electrode single chamber bioelectrochemical system (BES). Significant increase of degradation efficiency of TPHP in the BES was observed compared with open circuit and abiotic controls. The one-order degradation rates of TPHP (1.5 mg L−1) were increased with elevating sodium acetate concentrations and showed the highest value (0.054 ± 0.010 h−1) in 1.0 g L−1 of sodium acetate. This result indicated bacterial metabolism of TPHP was enhanced by the application of micro-electrical field and addition acetate as co-substrates. TPHP could be degraded into diphenyl phosphate (DPHP), hydroxyl triphenyl phosphate (OH-TPHP) and three byproducts. DPHP was the most accumulated degradation product in BES, which accounted more than 35.5% of the initial TPHP. The composition of bacterial community in BES electrode was affected by the acclimation by TPHP, with the most dominant bacteria of Azospirillum, Petrimonas, Pseudomonas and Geobacter at the genera level. Moreover, it was found that the acute toxic effect of TPHP to Vibrio fischeri was largely removed after the treatment, which revealed that BES is a promising technology to remove TPHP threaten in aquatic environment. [Display omitted] •A bioelectrochemical system with acclimatized electrode biofilm was applied for rapid degradation of TPHP.•Hydrolysis and hydroxylation were the main biotransformation pathway of TPHP in the BES, where DPHP was the main product.•Significant microbial community shifts in BES electrode biofilm were observed after TPHP acclimatization.•The acute toxic effect of TPHP to Vibrio fischeri was largely removed after the treatment. The TPHP degradation and toxicity removal can be enhanced by bioelectrochemical systems after acclimation, where Azospirillum, Petrimonas, Pseudomonas and Geobacter were dominant bacteria in anode biofilm.