Effects of hydrothermal treatment coupled pyrolysis on heavy metals in solid products from sewage sludge [污泥水热联合热解处理对固相产物中重金属的影响]

作者：Xie S.; Yu G.^*; Li J.; You F.; Wang G.; Wang Y.; Ma J.; Shang X.

来源：Chinese Journal of Environmental Engineering, 2018, 12(7): 2114-2122.

DOI：10.12030/j.cjee.201712095

• Heavy metals
• Hydrothermal treatment
• Leaching toxicity
• Pyrolysis
• Risk assessment
• Sludge
• Speciation analysis

Acid sludge (AS), basic sludge (BS) and their mixture (MS) were treated via hydrothermal treatment coupled pyrolysis. The change of BCR speciation and leaching toxicity of heavy metals (Cr,Mn,Ni,Cu and Zn) in solid products were investigated, and the potential ecological risk assessment of heavy metals was also performed. Results showed that the stability of heavy metals in the solid product (ASC) was improved after hydrothermal treatment coupled pyrolysis of AS, and the residual fractions of Ni and Zn in ASC were increased from 8.33% and 28.08% to 27.04% and 51.31%, respectively. However, the enhancement of stability of heavy metals in the solid product (BSC) was unobvious after hydrothermal treatment coupled pyrolysis of BS. The residual fractions of Cr and Cu in BSC were increased from 69.25% and 65.42% to 82.09% and 66.69%, and the residual fractions of other heavy metals in BSC were decreased. After hydrothermal treatment coupled pyrolysis of MS, the immobilization effect of heavy metals in the solid product (MSC) was further strengthened. Compared with the theoretical value, the residual fractions of Cr, Mn, Ni, Cu and Zn were increased from 89.03%, 55.85%, 47.33%, 55.39% and 73.19% to 98.09%, 66.72%, 48.49%, 89.07% and 86.70%, respectively. The leaching toxicity of heavy metals in MSC was below the USEPA standard and the potential risk degree was in a slight level. This work provides a novel idea for disposing sludge containing heavy metals.

• 单位
  中国科学院大学