BACKGROUNDN-nitrosodimethylamine (NDMA) is an emerging disinfection byproduct. The effective and economical method to control NDMA is to remove its potential NDMA precursors. In this study, experiments were conducted to investigate the removals of four typical NDMA precursors (dimethylamine (DMA), trimethylamine (TMA), dimethylformamide (DMFA) and dimethylaminobenzene (DMAB)) by activated sludge and isolated strains. RESULTSBatch experiments indicated that the specific degradation rates of the four NDMA precursors follow the order DMA > TMA > DMFA > DMAB; and under different redox conditions, follow the order aerobic > anoxic > anaerobic. In an anaerobic-anoxic-aerobic activated sludge system, the optimal hydraulic retention time (HRT) and sludge retention time (SRT) were 10 h and 20 days, respectively, for the removals of both NDMA precursors and nutrients. Bacterial strains were isolated from aerobic activated sludge and identified based on 16S rDNA sequence analysis. A pH of 8-9 and temperature of 30-35 degrees C were optimal for the removal of the four NDMA precursors by the isolated strains. Degradation of the four NDMA precursors by the isolated strains were fitted well by the Haldane model. CONCLUSIONThese results are helpful for knowledge of the removals of NDMA precursors during activated sludge treatment processes. (c) 2014 Society of Chemical Industry