污泥不同热处理工艺产物磷的浸出回收实验研究

Phosphorus recovery from products of sewage sludge via different thermal treatment processes

针对污泥阴燃处理灰渣开展了关于磷浸出回收性能的实验研究,并与传统焚烧和热解处理工艺所产生的焚烧灰和热解焦的磷浸出回收性能进行了分析对比。结果表明,热产物中磷含量与残碳含量有关,而热处理过程中磷留存率与反应剧烈程度等因素有关。热处理会降低污泥中磷的生物有效性,尤其是焚烧。污泥阴燃灰、焚烧灰和热解焦的磷浸出过程主要受反应物浓度和产物层扩散控制,浸出时间不应超过8 h。通过硫酸浸出污泥热处理产物的方法,单位质量热产物的磷浸出量为25.72~34.42 mg/g,可将原污泥中的磷回收59.30%~84.21%。进一步对浸出工艺进行工况优选,可在保持较高污泥磷回收率的同时大幅降低硫酸单位消耗量。

The experimental research on phosphorus leaching and recovery performance of sludge smoldering treatment ash was carried out,and the phosphorus leaching and recovery performance of incineration ash and pyrolysis coke produced by traditional incineration and pyrolysis treatment processes was analyzed and compared.The results showed that phosphorus content in thermal products was influenced by their residue carbon content,while phosphorus retention rate of thermal treatments was associated with their reaction violence and so on.Thermal treatment would decrease bio-availability of phosphorus in sewage sludge,especially incineration.The phosphorus leaching process of sludge smoldering ash,incineration ash and pyrolysis coke is mainly controlled by reactant concentration and product layer diffusion,and the leaching time should not exceed 8 h.Based on sulfuric acid leaching method,phosphorus leaching amount of unit mass thermal products reached 25.72—34.42 mg/g,which meant about 59.30%—84.21%of phosphorus in sewage sludge could be recovered.By further optimizing the working conditions of the leaching process,the unit consumption of sulfuric acid can be greatly reduced while maintaining a high sludge phosphorus recovery rate.