Removal performance of dissolved organic matters from municipal secondary effluent by different advanced treatment processes and the following disinfection by-products generation rules

Abstract

Abstract Various advanced treatment processes including ultrafiltration (UF), ozonation, enhanced coagulation, and biological aerated filter (BAF) have been applied to reduce dissolved organic matters (DOMs) from the secondary effluent of municipal wastewater treatment plants (MWTPs). In this study, DOMs were characterized and the relationship between DOMs characteristics and DBPs generation was investigated systematically. Results showed that BAF and ozonation processes could significantly affect DOMs characteristics in the treated effluents and the following DBPs generation. UF and enhanced coagulation reduced the production of DBPs by removing large molecular hydrophobic organics. The removal of low molecule DOMs by BAF resulted in a 67.6% reduction in trihalomethanes (THMs) production. Ozonation could oxide large hydrophobic DOMs into small hydrophilic molecules containing aldehyde and ketone groups, leading to 54% increase of chlorinated aldehydes (CHs) and halogenated ketones (HKs). Humic acid (HA) was the main organics type in DOMs and important precursor for THMs and dichloroacetonitrile (DCAN) formation. The generation of trichloromethane (TCM) showed a significant positive correlation (R2 = 0.987) with the specific ultraviolet absorbance at 254 nm (SUVA). Large molecule hydrophobic DOMs devoted the most to the formation of carbonaceous disinfection by-products (C-DBPs) and \(\text{N}{\text{H}}_{\text{4}}^{\text{+}}\)-N content was an important factor affecting the generation of nitrogenous disinfection by-products (N-DBPs). These results are important for the optimization of advanced treatment process in MWTPs, and controlling DBPs should consider the removal of low MW hydrophobic DOMs and the reduction of SUVA.