污泥水热联合热解处理对固相产物中重金属的影响

对酸性重金属污泥（AS）、碱性重金属污泥（BS）及其混合物（MS）进行水热联合热解处理，探讨了固相产物中重金属（Cr、Mn、Ni、Cu和Zn）的BCR形态变化与TCLP浸出毒性特征，并开展潜在生态风险评价。结果表明：AS经水热联合热解处理后得到的固相产物（ASC）中重金属的稳定性得到改善，Ni和Zn的残渣态比例显著增加，分别从8.33%和28.08%升至27.04%和51.31%；BS经水热联合热解处理后得到的固相产物（BSC）中重金属的稳定性改善不明显，Cr和Cu的残渣态比例分别从69.25%和65.42%升至82.09%和66.69%，而其他重金属的残渣态比例有所下降。MS经过水热联合热解处理，固相产物（MSC）中重金属的固化效果进一步提高。与理论值相比，Cr、Mn、Ni、Cu和Zn的残渣态比例分别从89.03%、55.85%、47.33%、55.39%和73.19%提高至98.09%、66.72%、48.49%、89.07%和86.70%，其浸出毒性均在USEPA标准以下，潜在风险程度为轻微水平，这为水热联合热解工艺处置重金属污泥提供新的思路。

Effects of hydrothermal treatment coupled pyrolysis on heavy metals in solid products from sewage sludge

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.