Determination Of Ten Haloacetic Acids In Water Using Gas Chromatography-triple Quadrupole Mass Spectrometer And To Minimize HAAFP By Enhanced Coagulation For The Effluent From Municipal Sewage Treatment Plant

Chlorination and chloramination have been widely used to inactivate pathogenicmicroorganisms in drinking water and wastewater treatment. However, reactions of thedisinfectants with natural organic matter （NOM） or dissolved organic matte （DOM）lead to the formation of disinfection byproducts （DBPs） in water. Haloacetic acids（HAAs） are the second most prevalent group of the identified disinfection byproductsin chlorinated water after trihalomethanes （THMs）. Studies have shown that，HAAs aresuspected to be carcinogenic and mutagenic, and to behave as developmental andreproductive toxins. Human exposure to HAAs in drinking water can be by drinking,bathing and swimming; HAAs in wastewater effluents accumulation would behazardous to natural water environments. Detection of HAAs in water is of increasingimportance to water quality management. To better reduce the concentration of HAAsin water, to develop a sensitive haloacetic detection method and a cost-effectiveadvanced treatment technology is very necessary.This paper mainly includes two parts:（1） A detection method for ten HAAs（MCAA、MBAA、DCAA、BCAA、DBAA、TCAA、BDCAA、CDBAAand TBAA）in water using gas chromatography-triple quadrupole mass spectrometry （GC-MS/MS）in multiple reaction monitoring mode has been developed and optimize thepreprocessor;（2） Enhanced coagulation removal efficiency of effluent organic matter（EfOM） in wastewater and the effects of enhanced coagulationon on HAAs formatiompotential were investigated. The main results and conclusions of this thesis are as follows:（1） A sensitive detection method for ten haloacetic acids （HAAs） in drinkingwater and wastewater has been developed based on liquid-liquid extraction （LLE）followed by acidic methanol derivatization and GC-MS/MS in multiple reactionmonitoring mode. Precursor ions and product ions of the ten HAA esters were firstidentied based on the mass spectra of the GC-MS/MS, and optimize the massspectrometry operating conditions.（2） The ratio of acidic methanol to MTBE extract of the HAAs （A/M） appearedto have profound effects on the HAAs methylation process and high ratio of A/M cansignificantly increase the derivative efficency of ten kinds of HAAs. In this study,derivatization reaction time of the analytes and volume of sodium sulfate solutionaddition following the methylation processes were also optimization. Determining theoptimal derivatization reaction time for ten HAAs was2h, the optimal volume ofsodium sulfate solution addition was7ml.（3） In comparision with the GC-ECD method, the GC-MS/MS method offers thefollowing advantages: higher sensitivity, fewer interfering peaks and cleaner baselines,and a short run time. Adoption the modified pretreatment procedure establish standardcalibration curves, The linear calibration range extended from0.5up to100mg/L（r²=0.9952-0.9998，n=8）, and limits of detection （LODs） were between0.012and0.079μg/L for all the ten HAAs, it can meet or better than the USEPA552.3. Theintra-day and inter-day relative standard deviations （RSDs） for the ten HAAs werefound in the range of1.02-6.86%and1.58-8.16%, respectively. Matrix effect by theanalysis of surface water, ground water and wastewater effluent samples spiked withconcentration is2.5and25μg/L ten kinds of HAAs mixed standard, recoveries forthe three kinds of water samples were90.3-100.2%,90.5-107.5%and76.9-100.4%,respectively.（4） Using the secondary effluents from beishiqiao sewage purification centersecondary sedimentation tank and aluminum sulfate enhanced coagulation, the resultsshow that, at pH=6.0, when the coagulant dosing is less than15mg/L, with theincrease of the amount of coagulant dosage, DOC, UV₂₅₄removal rate increasedsignificantly (coagulant dosing of15mg/L, DOC, UV₂₅₄removal rate were25.69% and27.94%, respectively); To further increase the amount of coagulant dosage, DOCand UV₂₅₄removal rate increased, but increase degree decreases gradually; at theoptimal coagulant dosage（90mg/L）, DOC, UV₂₅₄and THAA removal rate were36.60%,40.66%and55.52%, respectively; at coagulant dosage60mg/L, the removalrate of THAA reached a maximum of57%. When the coagulant dosage is at90mg/L（optimal coagulant dosage）, at pH=5.0the removal efficiency of EfOM was the best,DOC, UV₂₅₄, SUVA and THAA removal rates were34.07%,40.37%,9.54%and26.53%, respectively.（5） Total HAA （THAA） and bromide acetic acid （Br-HAAs） generated wereincreased to increase the concentration of bromide ions in the water samples, the BIFvalue increases and the more the HAA speciations shift in favor of the morebrominated compounds. Increasing iodine ion concentration, IIF value increases, butthe yield of THAAand Br-HAAs were decreased.（6） In this study, linear regression between HAA formation in water sample andDOC, UV₂₅₄, SUVA, linear correlation coefficient decrase in the order: UV₂₅₄, DOC,SUVA. UV₂₅₄and DOC can be used to characterize and predict some haloacetic acidsformation potential （HAAFP） in test water samples.