Triisobutyl phosphate biodegradation by enriched activated sludge consortia: Degradation mechanism and bioaugmentation potential.

This study investigated the ability of activated sludge (AS) to biodegrade triisobutyl phosphate (TiBP) after acclimation in an AS bioreactor by adding 50 mg/L TiBP. The bioreactor significantly increased the biotransformation rate of TiBP (2.15-12.7 d) over two months of acclimation. Seven transformation products (TPs) of TiBP were identified by high-resolution mass spectrometry, and hydrolysis, hydroxylation and dehydrogenation were the major biodegradation pathways of TiBP. TiBP degradation solutions at 0, 3, 7, and 10 h showed significantly toxic effects on zebrafish embryos, while the toxicity of TiBP degradation solutions at 24 h significantly decreased. Pseudomonas was inferred to be a specific bacterial population in the TiBP metabolic microbial consortium (TMMC) that degrades TiBP (p < 0.001). When TMMC (0.5, 1, and 2 g/L) was introduced into AS, the TiBP biotransformation rates (1.97, 2.05, and 2.26 d at 1.0 mg/L TiBP, and 0.09, 0.11, and 0.83 d at 30.0 mg/L TiBP) were significantly enhanced compared to the control (0.31 and 0.07 d) without TMMC inoculation. In general, this study provides new insights into the key species populations that accelerate TiBP degradation and promote the development of TiBP reduction biotechnology in WWTPs.