Pollution level and risk assessment of heavy metals in sewage sludge from eight wastewater treatment plants in Wuhu City, China

• Published in: Spanish journal of agricultural research : SJAR Vol. 18; no. 2; p. e1103
• Main Authors: Zhang, Hanwen, Huang, Yuee, Zhou, Shu, Wei, Liangchen, Guo, Zhiyuan, Li, Jinchun
• Format: Journal Article
• Language: English
• Published: Consejo Superior de Investigaciones Científicas (CSIC) 01.01.2020
• Subjects: agriculture; contamination evaluation; soil science; source identification
• ISSN: 1695-971X; 2171-9292; 2171-9292
• DOI: 10.5424/sjar/2020182-15796

Aim of study: To investigate the content, contamination levels and potential sources of five heavy metals (Hg, Pb, Cd, Cr, As) in sewage sludge from eight wastewater treatment plants (W1 to W8).Area of study: Wuhu, located in southeastern Anhui Province, southeastern China.Material and methods: The sewage sludge pollution assessment employed the single-factor pollution index, Nemerow’s synthetic pollution index, monomial potential ecological risk coefficient and potential ecological risk index. The potential sources among the five heavy metals were determined using the Pearson’s correlation analysis and principal component analysis (PCA).Main results: The mean concentrations of the heavy metals were 0.27 mg/kg (Hg), 70.78 mg/kg (Pb), 3.48 mg/kg (Cd), 143.65 mg/kg (Cr) and 22.17 mg/kg (As). W1, W5 and W6 sewage sludge samples showed the highest levels of heavy metal contamination, and cadmium had the highest contamination level in the study area. Pearson’s correlation analysis and PCA revealed that Pb and Cd mainly derived from traffic emissions and the manufacturing industry and that As and Cr originated from agricultural discharges.Research highlights: The pollution of cadmium in Wuhu should be controlled preferentially. The heavy metal pollution of W1, W5 and W6 sewage treatment plants is relatively high, they should be key prevention targets.