城市污水污泥与固体垃圾混烧过程中重金属迁移特性的研究

通过城市污水污泥与固体垃圾合成样品在小型管式焚烧炉内的混烧实验，采集灰渣样品进行XRF化学成分分析和浸出毒性鉴别测试，结合污水污泥焚烧过程中热力学平衡计算，定量表征了污水污泥中Cu、Pb、Zn、 Mn、Ni在焚烧过程中向底灰、飞灰和烟气迁移的特性及对灰渣的毒性影响。研究结果表明，污水污泥混烧显著提高了飞灰和底灰中重金属含量，其中Zn和Pb增加量最大，而Ni、Mn、Cu依次减少；随着有机氯的加入，飞灰中重金属含量呈现递增趋势，其中Zn表现最明显。毒性测试结果显示，污水污泥的混烧也导致了垃圾焚烧飞灰中Zn和Pb的浸出浓度超过中国对危险废物浸出的控制标准值。同时，重金属迁移的热力学平衡模型预测结果与实验结果差距较大。这表明热力学平衡计算方法还需进一步考虑影响重金属氯化物形成的其他因素，如在焚烧过程中反应动力学、焚烧室内氧气含量变化、与其他元素间的化学反应等。

Transferring characteristics of heavy metals during co-incineration of municipal sewage sludge and solid waste

Co-incineration tests of a synthetic house hold waste with sewage sludge were carried out in a lab-scale tubal incinerator and bottom ash and fly ash samples were collected. The sampled ashes were characterized for the concentration and leaching ability of Cu, Pb, Zn, Mn, and Ni. Furthermore, the calculation of thermodynamics equilibrium was conducted to identify the transfer of heavy metal elements into flue gas. The analyses show that the presence of sewage sludge greatly enriches the heavy metal element content in the bottom ash and fly ash in a decreasing order of Zn, Pb, Ni, Mn, and Cu. With the addition of organic Cl, the heavy metals in fly ash are increased, especially for Zn. Meanwhile, the fly ash from the tests with sewage sludge added presents toxicity due to the marked Zn and Pb leaching that exceeds the limit values legislated by National Environmental Law for Hazardous Solid Waste. Discrepancies between model predictions and experimental results are evident, which indicates that considering the kinetics，oxygen content in the incinerator and possible chemical reactions between these heavy metal elements and other elements in the formation of metal chloride gaseous species is needed.