Risk Assessment Of Typical Viruses And Pharmaceuticals In Reclaimed Water Of Urban Sewage

In the current situation of serious shortage of water resources,reclaimed water is recognized as the"second water source".Its reasonable reuse can reduce the re-pollution of water environment and alleviate the shortage of water resources,which has the triple benefits of society,economy and environment.With the continuous popularization and application of reclaimed water,some harmful pollutants in the process of reuse may bring certain potential harm to human health and ecological environment safety.In order to ensure the safety of reclaimed water in the process of reuse,it is of great practical significance to evaluate the potential hazards and risks of various risk factors to human health and ecological environment in different reuse processes,so as to provide theoretical basis and data support for the risk management and control of local reclaimed water reuse.Three typical human enteric viruses（Ad V,EV,RV）and five typical pharmaceuticals（OFL,ROX,SMZ,TC,AP）were studied by Quantitative Real-time PCR and HPLC-MS,respectively.The viruses and pharmaceuticals in the reclaimed water of three municipal wastewater treatment plants in Qingdao and their supply river sections were detected.Based on the detection results,combined with the dose-response relationship,the"four step"method was used to evaluate the human health risks of occupational and non occupational personnel exposed to the above eight risk factors in different ways of reclaimed water reuse,such as urban greening,road dust,landscape water,household greening and toilet flushing.At the same time,with reference to the toxicity value of pharmaceuticals combined with the risk level,the risk quotient value（RQs）method was used to evaluate the risk of ecological environment when WWTP-2phase IV grade tertiary effluent was supplied to the river.The main conclusions were as follows:1.Health risk assessment of typical viruses in reclaimed water（1）Among 56 samples,only 4 samples were positive for HAd V,and the detection concentration was in the range of ND～924.44 copies/L,while EV and RV were not detected out.（2）Taking 10^-4/a as the acceptable personal annual risk of virus infection,WWTP-1 reclaimed water plant effluent,WWTP-2 Phase I and Phase IV project tertiary treatment effluent reuse for urban greening,road dust reduction,landscape water,household greening,flushing toilets,etc.During those route,HAd V poses a certain health risk to the exposed population and the risk of one-time infection P_i of professional personnel is slightly higher than that of non-professional personnel.（3）By comparing the health risks of HAd V in reclaimed water with urban greening,road dust reduction,landscape water,household greening and toilet flushing,we can see that the health risks of the above recycling ways to professional personnel are as follows:urban greening≈road dust reduction≈landscape water>household greening>toilet flushing,the health risks to non-professional personnel are as follows:urban greening>road dust reduction>landscape water>household greening>toilet flushing.2.Health risk assessment of pharmaceuticals residues in reclaimed water（1）The detection concentrations of OFL,ROX,TC and AP in the reclaimed water were 0.96～11.13 ng/L,0.79～7.52 ng/L,ND～0.01 ng/L,ND～0.01 ng/L,whlie SMZ was not detected out.（2）Taking 10^-8/a as the negligible risk level of pharmaceuticals residues to human health,the annual health risks of OFL,ROX,TC and AP to the exposed population were negligible when the tertiary effluent of WWTP-2 phase IV project is reused for urban greening,road dust reduction,landscape water,household greening and toilet flushing.（3）By comparing the health risk of each pharmaceutical residue in reclaimed water through the reuse ways of urban greening,road dust reduction,landscape water,household greening and toilet flushing,it can be seen that the health risk of each pharmaceutical residue in the above recycling ways to professional personnel is as follows:road dust reduction>urban greening>landscape water>household greening>toilet flushing,the health risk to non-professional personnel is as follows:urban greening>road dust reduction>household greening>landscape water>toilet washing.3.Ecological risk assessment of pharmaceuticals residues in reclaimed water supply channels（1）The detected concentrations of OFL,ROX and AP in the water samples of the Wuyang section of the reclaimed water supply river were 1.75～10.47 ng/L,1.38～7.36ng/L,ND～1.10 ng/L,SMZ and TC were not detected out.OFL presents a medium risk to aquatic organisms exposed to this concentration,ROX and AP present a low risk to aquatic organisms exposed to this concentration while SMZ and TC pose no significant risks to the river benthic ecosystem.（2）The detected concentrations of OFL,ROX,SMZ,TC,and AP in the upstream water samples of the general drainage outlet of the fourth phase of the reclaimed water project were 1.48～9.72 ng/L,ND～5.88 ng/L,ND～0.19 ng/L,ND～2.15 ng/L,while SMZ was not detected out.OFL presented a moderate risk to aquatic organisms exposed to this concentration.ROX,TC and AP present a low risk to aquatic organisms exposed to this concentration while SMZ had no significant risk to ecological environment.