Transformation of Disinfection Byproduct Precursors During the Wastewater Regeneration Processes

Abstract

Disinfection byproduct(DBP) precursors during the wastewater regeneration processes were separated into hydrophilic fraction(HPI), hydrophobic fraction(HPO) and transphilic fraction(TPI) with macroporous resin. DBP precursors in these water samples were characterized with fluorescence excitation emission matrix, Fourier transformation infrared and nuclear magnetic resonance, and were further tested for their DBP formation potential(DBPFP) after chlorination. The results indicated that main DBP precursors in sewage were humic acid and aliphatic hydrocarbons, and were mainly dominated by HPI. Primary treatment(sedimentation) could effectively remove hydrophobic humic acid through the mutual exclusion between HPO and water. The removal of humic acid would lead to the obvious reduction of carbonaceous disinfection byproduct formation potential(C-DBPFP). In addition, nitrogenous disinfection byproduct formation potential(N-DBPFP) was found to be increased due to the increase of DON/DOC value. Although secondary treatment(biotreatment) was effective in removing humic acid and aliphatic hydrocarbons, it could produce a large amount of soluble microbial products(SMP), which led to the enhancement of HPO percentage. And the accumulation of SMP resulted in the significant increase of C-DBPFP and N-DBPFP. Humic acid and hydrophobic SMP could be removed by the advanced treatment(cloth filtration), leading to the reduction of HPO percentage and the increase of HPI percentage. The decrease of humic acid and hydrophobic SMP would cause the reduction of C-DBPFP and N-DBPFP in the advanced treatment.