| Polycyclic aromatic compounds(PACs), have been caused conerns due to their potential biological toxicity and bioaccumulation. Wastewater treatment plant(WWTP) is considered to be an important medium for the transport and transformation of organic pollutants. As a sink for municipal wastewater along with street runoff and dry/wet deposition, wastewater treatment plant(WWTP) was considered to be an important medium for the transport and transformation of organic pollutants, such as PCAs. This study attempted to comprehensively investigate the levels, occurrence, and fate of PACs by using the Long-term monitoring data WWTP in Harbin and the Fugacity-Based Sewage Treatment Plant model.The wastewater and sludge samples were collected during 2011 to 2016 to investigate the levels, occurrence, and fate of PAHs and BFRs and provide data support for the model. The mean concentration of Σ16PAHs in the influent, effluent and sludge were 6 471 ng/L, 989 ng/L and 8 970 g/g dw, respectively, which were at a higher level of the global range. The mean concentrations of the total PBDEs in the influent, effluent and sludge were 152 ng/L, 16.2 ng/L and 503 g/g dw, respectively, which were at the low end of the global range. The level of the total NBFRs ranged from 24.5 to 107 ng/L, 0.95 to 20.3 ng/L and 305 to 1,202 ng/g dw in the influent, effluent and sludge, respectively. Overall, on a daily basis, the mass loading of the Σ16PAHs into the WWTP, out of the WWTP with the effluent and sludge, were estimated to be 1,204, 384.8 and 484.4g, respectively. The removal efficiency of Σ16PAHs was 68.0%, in which 40.2% was absorbed on sludge and 27.8% was removed through volatilization. The removal efficiency of ΣPBDEs and ΣNBFRs in the WWTP were 89.4% and 76.2%, respectively. Most of the PBDEs and NBFRs were removed from the WWTP by absorbed on sludge, which accounted for 57.7% and 57.0%. In addition, it should be noted that there was mass losing of PBDEs and NBFRs in the WWTP, which accounted for 31.6% and 19.2% for PBDEs and NBFRs, respectively.A fugacity-based sewage treatment plant model was developed including environmental medium of sewage, sludge, air and soil using Microsofte Excel 2010 to investigate the environmental behavior of PACs. Significant correlation was found between model simulation results and monitoring results of PAHs and BFRs.A soft of fugacity-based sewage treatment Plant model was developed to improve the computing capability of the model. The initial parameter database, simulation results, and actual monitoring database were developed using Micosoft Acesses 2010 database management system. The relationship between the proportion of the organic pollutants in the mediums and their phys-chemical parameters was ananlysis using multiple linear regression method. The fitting resualts shown that the proportion of adsorption on the sludge, biodegradation and volatilization were fitting well with the phys-chemical parameters. The proportion of adsorption on the sludge was consisted well with the monitoring results. Combined with model simulation database and the monitoring database, we can found that only a few compounds of PAEs in wastewater treatment plant could be biodegradated and removed from the environment, the degradation efficiency range from 50.7% to 86.1%. Compouds with the vapour pressure more than 158 Pa have a part removed from wastewater treatment plant through volatilization, which accounted for 2.8% to 9.7%. The compounds with the values of log Kow, log Koc, log Koa, and water solubilty in the range of 4.5- 12.6, 4.2- 11.8, 7.5- 21.5 and 4.0×10-9- 2.6×10-1 g/L were mainly removed from the WWTPs by absorbed on sludge. In addition, the compounds with the values of log Kow, log Koc, log Koa, and water solubilty in the range of <4.0, <4.0, 6.5 and >10 g/L were mainly removed from the WWTPs with the effluent. The transition and transform rule of PACs in the WWTPs were summarized, which could provide a scientific basis for predicting the fate and evaluating the ecological risk of of new compiunds. |
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