Assessing pollution and risk of polycyclic aromatic hydrocarbons in sewage sludge from wastewater treatment plants in China’s top coal-producing region

  • Qihang Wu
  • Zhineng Liu
  • Junyan Liang
  • Dave T. F. Kuo
  • Shejun Chen
  • Xiaodong Hu
  • Mingjun Deng
  • Haozhi Zhang
  • YueHan LuEmail author


Managing and disposing of sewage sludge have been a severe environmental challenge around the world. China produces hundreds of million tons of sewage sludge annually, and a better understanding of the extent and risk of the associated pollution is of critical importance for implementing environmentally safe regulations and practices. The present study examined the quantity, composition, source, and risk of polycyclic aromatic hydrocarbons (PAHs) in sewage sludge from 18 wastewater treatment plants (WWTPs) in Shaanxi, one of China’s top coal-producing provinces. The total concentrations of 16 PAHs varied from 778 to 3264 ng/g dry weight, which is below the upper safety limit (5000 ng/g dry weight) set for the disposal of sludge from municipal wastewater treatment plants for agricultural use in China. However, the concentration of individual PAH compound exceeded the acceptable level prescribed by the Netherland Soil Standard. Three-ring PAHs were the most abundant constituent (50% of total PAHs on average), followed by four-ring PAHs averaging 25%. Relative to sludge PAHs in the same region a decade ago, the total concentrations decreased by more than 27% and the composition shifted to a more pronounced dominance by low molecular weight compounds. This compositional shift suggests higher contributions of petrogenic sources, which may reflect China’s increasing consumption of petroleum products over the past decade. The flux of sludge PAHs from each WWTP was positively correlated with the corresponding city’s GDP and population, and the total flux amounted to over 100 kg each year for WWTPs in the Xi’an city. The mean toxicity equivalent quantity (TEQ) value was more than twice higher than the value recommended by the Netherlands Soil Standard, and seven carcinogenic PAHs were the primary contributor (i.e., 89–99%) of the TEQ. Collectively, our findings demonstrate that sewage sludge PAHs in Shaanxi constitute a significant source of environmental pollution and toxicity, which cautions against the direct discharge and reuse of sewage sludge and further highlights challenges in managing and disposing of the vast quantities of sewage sludge in China.


Polycyclic aromatic hydrocarbons Sewage sludge Wastewater treatment plant Toxic equivalent quantity Risk assessment Shaanxi Coal production Coal consumption 


Funding information

The project was funded by Guangzhou University’s 2017 training program for young top-notch personnel (BJ201713), National Natural Science Foundation of China (Project No. 21477100), Strategic Research Grant (Grant No. 7004184), CityU Startup Grant (Grant No. 7200384), MFPRC Grant (Grant No. 9680132). Y. Lu acknowledges the support from Center for Freshwater Studies Faculty Research Grant from the University of Alabama, the Alabama Water Resources Research Institute Grant (2016–2017), and the 2018 Sabbatical Fellowship Program from the South University of Science and Technology in China.

Supplementary material

10661_2019_7225_MOESM1_ESM.docx (35 kb)
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Copyright information

© Springer Nature Switzerland AG 2019

Authors and Affiliations

  1. 1.Key Laboratory for Water Quality and Conservation of the Pearl River Delta, Ministry of Education, Institute of Environmental Research at Greater BayGuangzhou UniversityGuangzhouChina
  2. 2.School of Civil EngineeringGuangzhou UniversityGuangzhouChina
  3. 3.Department of Architecture and Civil EngineeringCity University of Hong KongKowloon TongHong Kong
  4. 4.Shenzhen Research InstituteCity University of Hong KongShenzhenChina
  5. 5.State Key Laboratory of Organic Geochemistry, Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhouChina
  6. 6.Department of Geological SciencesUniversity of AlabamaTuscaloosaUSA
  7. 7.SUSTech Academy for Advanced Interdisciplinary StudiesSouthern University of Science and TechnologyShenzhenChina

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