Optimization of the precursor removal of dichloroacetonitrile (DCAN), an emerging nitrogenous disinfection by-product, in an up-flow BAC filter

- Optimization for the precursor of DCAN by UBACF was studied.
- High removal efficiency of DCAN, 64.4% with the optimized parameters.
- More microbial richness and even distribution in the improved process.
- Alphaproteobacteria, Bacilli and Betaproteobacteria were dominant bacteria.

The process parameters of the up-flow biological activated carbon filter (UBACF) were optimized in a pilot-scale trial for controlling the precursor of dichloroacetonitrile (DCAN), an emerging nitrogenous disinfection by-product. The experiments were performed using a central composite design (CCD) with the response surface methodology (RSM). The results showed that the removal efficiencies of formation potentials (FP) of DCAN increased from 28.9% to 64.4% with the optimized ozone dose, expansion rate of BAC and backwashing cycle, being scheduled to 1.52 mg/L, 27% and 9.5 d, respectively. Excitation and emission matrix (EEM) spectra indicated that the fluorescence peaks of aromatic protein (AP) and soluble microbial products-like (SMPs)-like region were weakened significantly in the effluent of improved process (IP) with optimization, which were main precursors of DCAN. The bacterial community before and after the optimization of UBACF was determined using the high-throughput sequencing technology. The class and genus of microorganism demonstrated that the IP had a more diverse microbial community and more even distribution of species in BAC filter. It was favor of the growth of Alphaproteobacteria, Bacilli and Betaproteobacteria attached to the BAC particles, which could biodegrade effectively the precursors of DCAN.