Application Biomarker To Assess Population Served By Wastewater Treatment Plants

Investigation and monitoring of drug use has always been a difficulty in public security management and crime prevention.Wastewater-based epidemiology(WBE)is a new approach to investigate drug use by analyzing substance residues in municipal sewage.It can provide objective,real-time,and small-scale drug use situation.However,there are some uncertainties in WBE including the estimation of the population served by wastewater treatment plants(WWTPs).To solve this scientific problem,this study proposes a real-time population estimation method based on population biomarkers.In this study,11 WWTPs in Dalian was selected to sample.In 2017,influent samples were collected continuously for 11 months.The concentration data of methamphetamine and four biomarkers ammonia nitrogen,cotinine,nicotine,and caffeine were analyzed by solid phase extraction(SPE)and GC-MS.On this basis,methamphetamine use per capita was predicted with ammonia nitrogen,cotinine,nicotine and caffeine as population biomarkers,respectively.According to the unstable characteristics of single biomarker,a combined application of multiple biomarkers is proposed to estimate population.The weight coefficients of various biomarkers were determined by subjective weighting method(analytic hierarchy process,ordinal relationship method,ring ratio scoring method)and objective weighting method(principal component analysis method,entropy method,coefficient of variation method,CRITIC method),and multiple parameter models were established to predict the use of methamphetamine in Dalian.By comparing three subjective and four objective weighting methods,it is found that the subjective weighting method focuses on the biomarker of ammonia nitrogen,while the objective weighting method focuses on the biomarker of caffeine.The main reason is that ammonia nitrogen belongs to endogenous biomarkers with single source,high and stable concentration in wastewater,which is suitable for population biomarkers;caffeine belongs to exogenous biomarkers with more sources,lower concentration and greater fluctuation,so the objective weighting method will focus on the factors with greater fluctuation of concentration.Therefore,the objective weighting method has some defects in the selection of biomarkers.On this basis,it is suggested that the multi-parameter population forecasting model based on subjective weighting methods be applied to the long-term monitoring of methamphetamine use,which can improve the accuracy of forecasting results,effectively evaluate the effect of public security anti-drug action,grasp the trend of drug user mobility,and prevent and intervene illicit drug use.It also provides theoretical support and scientific basis for combating drug crimes.