Removal Efficiency And Mechanism Of Pesticides And Veterinary Drugs By Traditional Tap Water Treatment Process

Currently,pesticides and veterinary drugs are playing crucial roles in development of plantation and breeding industry in China.Highly yielded,widely used pesticides and veterinary drugs keep entering aquatic environment through various pathways,and threatening drinking water safety and human health.The combined pollution status of pesticides and veterinary drugs,their removal efficiency by water treatment process and health risk should be of great concern,which make poeple pay more attention to the removal of trace organic pollutants by traditional water treatment process.In this research,280 kinds of commonly used pesticides of 40 categories and 100 kinds of commonly used veterinary drugs of 17 categories as target compounds,determination methods using LLE/SPE followed by GC-MS/MS and UPLC-MS/MS were applied to monitoring the combined pollution in water samples from different treatment steps(raw water,water after sedimentation,water after filtration and finished water)of two tap water plants in Xiamen city,where two traditional tap water treatment pocesses are running.The seasonal pollution characteristics,removal efficiency and mechanism,preliminary health risk assessment.The main results are as the following:1.Combined pollution and removal of pesticides and veterinary drugs in water treatment process11 antibiotics of sulfonamides,chloramphenicols,macrolides and 13 pesticides of organophosphates,carbamates,azoles,neonicotinoids were frequently detected in raw water with concentration 0.15?83.12 ng/L for antibiotics and 0.11?33.10 ng/L for pesticides respectively.Seasonal combined pollution characteristics of detected pesticides and veterinary drugs in raw water were observed as rainy season>dry season>normal season.8 antibiotics(ND?40.41 ng/L)and 13 pesticides(ND?21.01 ng/L)were detected in finished water through water treatment process.The overall removal efficiency were calculated as approximately 47.44%-100%of the detected pollutants by water treatment process.Antibiotics were much more easily removed than pesticides.The residual concentration of detected pollutants in each step gradually decreased through treatment progress with the trends of sulfonamides>chloramphenicols>macrolides for antibiotics and carbamates>azoles>organophosphorus>neonicotinoids for pesticides.Removal contribution of each step were different for pesticides and antibiotics,and an overall trend of coagulation>disinfection>filtration was observed.Concentration of some target compounds got increased instead of decreased after treated by some treatment step.2.Study on removal efficiency and mechanism of pesticides and veterinary drugs in traditional water treatment processIn coagulation step,the removal efficiency increased with the coagulant dosage increased,except for florfenicol.The optimum coagulant dosage is 16.0 mg for veterinary drugs and 12.0 mg for most pesticides.The removal efficiency of quinolones and lincomycin in this step were higher,but much more complexed for different pesticides.In filtration step,the adsorptive effect of targets by quartz sand mainly showed 3 trends,(1)concentration of target compounds decreased due to unsaturated adsoption by quartz sand.(2)concentration of target compounds kept stable due to almost saturated adsorption.(3)concentration of target compounds increased due to the saturation and release of target compounds adsorpted to quartz sand.In disinfection step,the removal efficiency of targets increased with the prolonging of chlorination reaction time.But the removal efficiency were different for different targets under different reaction duration3.Preliminary health risk assessment of detected pesticides and veterinary drugs residues in finished waterThe health risk of detected pesticides and veterinary drugs in finished water was preliminarily assessed.Results showed that detected pesticides and veterinary drugs in finished water would not be harmful to human health due to low health risk index between 10-2?10-9.The health risk index of pesticides showed seasonal variation of dry season>rainy season>normal season.Among detected pollutants,butachlor was found relatively high risk to children due to highest index of 10-2 and should be concerned.