Characteristics of disinfection by-products precursors removal from micro-polluted water by constructed wetlands

Abstract

The goal of this research was to investigate the performance of constructed wetlands (CWs) for the removal of dissolved organic carbon (DOC) and access the possible, formation of disinfection by-products (DBPS) after CWs treatment. A mixture of raw water from Yangtze River was spiked directly into pilot-scale CWs to assess impacts on various factors, including the removal of DOC, ultraviolet absorbance at 254nm (UV254), specific ultraviolet Absorbance (SUVA), disinfection by-products formation potential (DBPFP), trihalomethane formation potential (THMFP), and haloacetic formation potential (HAAFP). The average removal of CODMn, NH4+-N, TN, DOC, UV254, THMs, and HAAs were 38.40%, 41.70%, 25.90%, 30.96%, 47.58%, −20.52%, and 25.22% respectively. CWs could degrade complicated organic matter into those with lower molecular weight, but could not further change to carbon dioxide and water. The average molecular weight of THMs in effluent flow declined to the level below, and high molecular weight organic compounds were more likely to form HAAs. The SUVA had no obvious relationships with the removal of specific trihalomethane formation potential (STHMFP), but had apparent relationship with the removal of specific haloacetic formation potential (SHAAFP) in CWs (p<0.5), suggesting that aromatic moieties had a higher apparent propensity to form HAAs than THMs.