Groundwater pollution risk evaluation of pharmaceuticals and personal care products in land application of sludge

In order to further clarify the groundwater pollution risk of the pharmaceutical and personal care products (PPCPs), also known as emerging organic contaminants, in land application of sludge, groundwater pollution risks of 29 PPCPs under sand and loam soil conditions are primarily evaluated using a mathematical model. The results show that ciprofloxacin, ofloxacin, oxytetracycline, norfloxacin and caffeine have risk index values higher than 1 under sand soil conditions, indicating high groundwater pollution risks. Except caffeine, all the other 4 PPCPs with high groundwater pollution risks are antibiotics, which need to be further monitored and controlled in groundwater. Under loam soil conditions, all the 29 PPCPs show low groundwater pollution risks. Sorption is the main factor affecting the groundwater pollution risk of PPCPs. Sensitivity analyses indicate that the half-life of PPCPs in soil, organic carbon partition coefficient, soil density, organic carbon content and depth of the zone with organic matter are the key parameters affecting the model output. Uncertainty analyses show that changes in the organic carbon partition coefficient and half-life of PPCPs in soil have great impact on groundwater pollution risks. Test and verification show that PPCPs with higher groundwater pollution risk index values had higher detection rates in groundwater, indicating that the evaluation results are reliable. Further researches on degradation products of PPCPs, their safe levels in groundwater, interactions between coexisting PPCPs and medium heterogeneity effects should be strengthened in order to evaluate the groundwater pollution risk of PPCPs with reasonable accuracy.