Occurrence Of Typical PPCPs In Sewage Sludge From WWTPs In Beijing And Shenzhen

Pharmaceutical and personal care products, namely PPCPs, have received much attention in recent years due to their wide and continuous use, and potential adverse effects on ecosystem and human health. Since traditional WWTPs are not originally designed for removing PPCPs, their capacities for PPCP removal are rather limited. PPCPs go back to the environment through effluent and sludge. Sludge plays as a sink for PPCPs and becomes a potentially nonpoint source of PPCPs into the environment.This study established an analytical method based on pressurized liquid extraction, solid phase extraction and high performance liquid chromatography-tandem mass spectrometry, which can determine 7 PPCPs at the same time. The method met the analytical need for environmental samples by optimizing the pretreatment procedures.This study mainly focused on the occurrence of PPCPs in dewatered sewage sludge and their emissions through sludge disposal from wastewater treatment plants(WWTPs). The sludge samples were obtained from 12 WWTPs in two typical cities, Beijing and Shenzhen in China. Four of seven PPCPs, diclofenac acid, carbamazepine, mefenamic acid and N,N-diethyl-m-toluamide were detectable in dewatered sludge from both cities with the concentration of 21-11,060 μg/kg, while the other three compounds, trimethoprim, chloramphenicol and bezafibrate were not detected. In addition, the emissions of these four detected compounds were high with the highest emission of diclofenac acid and carbamazepine being 238 g/d and 86 g/d, respectively. Diclofenac acid and carbamazepine is the main PPCPs going back to the environment through sludge disposal in Beijing and Shenzhen respectively. The total emission of these four detected PPCPs through sludge disposal ranged from 1.1-254 g/d in Beijing and 1.3-87.2 g/d in Shenzhen. Based on this, total emission of these four detected PPCPs through effluent disposal ranged from 16.6-933 g/d in Beijing and 59-4,746.1 g/d in Shenzhen. And the total emission through WWTP is 19-1,098 g/d in Beijing and 61.1-4,833.2 g/d in Shenzhen. In addition, carbamazepine, mefenamic acid and N,N-diethyl-m-toluamide mainly go back to the environment through effluent, while diclofenac acid goes back to the environment through effluent and sludge. And diclofenac acid is the main PPCP discharged through WWTP in Beijing, while carbamazepine and mefenamic acid are the main PPCPs discharged through WWTP in Shenzhen. The emission of DEET through WWTP in Shenzhen is a little bit higher than Beijing.The occurrence and emission of PPCPs through sludge and effluent should be paid more attention. Control strategies need to be considered, such as managing PPCP usage and disposal, changing wastewater treatment operating conditions, reducing sludge production and setting maximum allowable PPCP levels in sludge. Further research on transfer of PPCPs to soil and eventual to groundwater during sludge disposal and environmental risks is essential.