Pollution Characteristics Of Pharmaceuticals And Personal Care Products In Landfill Leachates

Landfill leachate is one of the important emission sources of pharmaceutical and personal care products(PPCPs)in the water environment.Although extremely high concentration levels of PPCPs were observed in landfill leachates,landfill leachates have received much less attention compared with other emission sources of PPCPs.In the present study,we developed a reliable analytical method for the determination of PPCPs belonging to multiply classes in landfill leachates,investigated the pollution characteristics of PPCPs in landfill leachates in 12 landfill sites or comprehensive municipal solid waste disposal sites in major cities in China,revealed the concentration variations of PPCPs in landfill leachates and identified the influencing factors.The results provided evidence for comprehensively understanding the environmental impacts of PPCPs in landfill leachates to the surrounding environment.An analytical method based on the solid-phase extraction and ultra-high performance liquid chromatography-tandem mass spectrometry for the simultaneous analysis of 68 PPCPs in landfill leachates was developed.Pretreatment conditions(sample pH,eluent,and chelating agent)and instrumental analytical parameters were optimized.The optimized method had the recoveries of 70%-130%for 60 PPCPs,low method quantification limits(3 ng/L-1.24 μg/L),and good repeatability and reproducibility(RSD<20%),realizing the accurate quantification of trace-level PPCPs in landfill leachates.Landfill leachate samples collected from 12 landfill sites or the comprehensive municipal solid waste disposal sites in major cities in China were collected and analyzed.Thirty-eight PPCPs were detected with detection frequencies of larger than 50%and the median concentrations ranged from 8.5 ng/L-38.1 μg/L.In general,non-antibiotics exhibited higher pollution levels than antibiotics.Socio-economic parameters,garbage classification,and landfill characteristics had an influence on the occurrence of PPCPs in landfill leachates.Cites characterized by higher economic development levels have more opportunities to gather a larger population,and the amounts of PPCP consumption or discharge would be higher.The landfills,which were open and mainly received municipal waste with a large quantity,had higher PPCP concentrations in landfill leachates.The garbage classification resulted in decreased amounts of PPCPs disposed of in landfills.A successive monthly monitoring program for two years was conducted at a typical landfill located in East China.The results indicated a distinct seasonal variation in PPCPs in landfill leachates-elevated concentration levels from April to September were observed compared with other months(the mean concentration of PPCPs is 17 μg/L,while the mean concentration in other moths is 3.8 μg/L).Rainfall played a considerable role in mediating PPCP concentrations in leachates,and the variation in response to rainfall was related to rainfall precipitation and the hydrophilicity of PPCPs.Torrential rain events(i.e.,24 h cumulative precipitation of 50.0 mm99.9 mm)led to the most significant increases in PPCP concentrations in landfill leachates(72%of PPCPs showed elevated concentrations after rainfall).The hydrophilic PPCPs exhibited a larger seasonal fluctuation and could be more easily transported from the MSW refuses into landfill leachates during rainfall events.PPCP removal performances by nine on-site full-scale landfill leachate processes were also evaluated.The results showed that most PPCPs were efficiently eliminated,with the median removal efficiencies of 88%-96%.The successive monthly monitoring program in the typical landfill indicated a seasonal variation for PPCP removal during leachate treatment processes.Temperature was the most important influencing factor;rainfall had an adverse effect on PPCP removal during the biological treatment process(median removal before rainfall is 74%,while median removal after rainfall is 63%),but the impacts during the combined treatment process were negligible(median removal before rainfall is 80%,while median removal after rainfall is 77%).According to the results in this study and other relevant literature,the pollution contribution and impact of landfills on the water environment were evaluated.The total mass load of 106 PPCPs in landfill leachates in China was 12.9 t/year,and the mass load discharging from landfills to the water environment in China was 0.02 kg/year-318 kg/year with a high probability,and might be larger than 318 kg/year with a low probability but less than 4360 kg/year.If landfill leachates,treated though,were discharged into the nearby water environment,they would cause a persistent environmental risk to the nearby water environment;while if treated landfill leachates were discharged into the receiving municipal WWTPs,they may have negligible impacts on the municipal WWTPs.