Control And Distribution Of DBPs In Drinking Water In Hangzhou

Since disinfection by-products (DBPs) are becoming a kind of substance for human health risk, many researches on DBPs have been developed.The purpose of this thesis was to explore the effective technology for controlling the formation of THMs and HAAs in drinking water in Hangzhou. the formation mechanism, the concentration distribution and the removal methods of THMs and HAAs were discussed. The main conclutions were followed as:(1) Researches for the reliable and accurate analytical methods and the distribution were developed for THMs and HAAs in drinking water.Good determination limits and recoveries were discovered by the analytical methods which were along with the pretreatment of headspace and derivatization for the trace levels of THMs and HAAs in drinking water. The determination limits and recoveries of methods were >0.21μg/L and 79.45%~83.12% of THMs, and >0.04μg/L and 75.59%~ 120.57% of HAAs. Eight water samples in Hangzhou were invesgated, and it can be observed that the distributions of THMs and HAAs were different: THMs and HAAs were higher in spring than in winter;THMs and HAAs were lowest in forward positions of Qiantang River, highest in middle positions and middle in backward positions;The composition of THMs were DBCM>TCM>BDCM and BCAA> TCAA> DCAA>MBAA of HAAs.(2) Studies on the formation and effect of THMs and HAAs in drinking water are developed.The results showed that, THMs and HAAs were different with variable conditions of DBPs precursors, water temperature, applied chlorine dose, reaction time and pH. TOC and UV-254 had a weak correlation with THMs precursors, but a strong correlation with HAAs precursors;The total THMs concentration increased with increasing pH value from 5 to 10. but the total HAAs concentration slightly decreased with increasing pH value;the chlorine dose and reaction time had a functional relationship with the formation of THMs and HAAs. and the concentration of THMs and HAAs also increased with increasing temperature in the normal range.(3) Studied on the removal efficiencies for NOM, trihalomethane formation potentential (THMFP) and haloacetic acids formation potentential(HAAFP) by nanofiltration(NF) membrane process.NOM composed with DBPs precursors were characterized and the removal efficiencies of NOM fractions were evaluated in the study. The results showed that NOM from Qiantang River were composed mainly by lowest molecular weight (MW) (<2K) and highest MW (>100K) organic matters. The NF membrane process was the best way to remove NOM, THMFP and HAAFP. The removal efficiencies of DOC, UV-254. THMFP and HAAFP were 80.1%, 95.7%, 86.9% and 96.6% respectively. The efficiency for THMFP was lower than HAAFP mainly because the GAC had different removal efficiency between THMFP and HAAFP.