城市污水处理厂污泥固化处理技术研究

New technology for solidifying sewage sludge

以水泥、粉煤灰和煤渣为固化剂对城市污水处理厂的污泥进行固化处理。通过抗压强度和重金属浸出毒性来评价污泥固化块的力学性质和安全性能;采用XRD和SEM分析污泥固化块的组成和微观结构。结果表明,水泥、粉煤灰、煤渣对污泥固化块的抗压强度具有有利影响。当水泥掺量为0.07kg/kg,粉煤灰掺量为0.02kg/kg,煤渣掺量为0.06kg/kg,即m(污泥)∶m(水泥)∶m(粉煤灰)∶m(煤渣)=1∶0.07∶0.02∶0.06时,养护7d的污泥固化块抗压强度约为1.8MPa。该配方的污泥固化块对重金属具有较好的固定效果,浸出液中重金属质量浓度满足国家标准。污泥的含水率对污泥固化效果具有不利影响。

The present paper attempts to introduce a new technology for sewage sludge solidification by taking cement, PFA and cinder as the solidifying agent. The said technology has been developed through compressive analysis of the strength of solidified sludge and observation of the leaching property of heavy metals extracted from it, and then determining its micro-structural characteristics with XRD and SEM. According to our experimental process, once the investigative test and the orthogonal experiment and the single-factor analysis were done, it would be possible to prepare our optimal solidification prescription. In the experiments, we have used cement, PFA and cinder as binding substance, added with 0.07 kg/kg, 0.02 kg/kg and 0.06 kg/kg, respectively. Results of our experiments have shown that the strength of the solidified sludge with cement, PFA and cinder proves to be considerably higher than the standard one for landfill, for cement, PFA, cinder, and plaster can help to solidify the sludge with better compressed strength. After curing 7 d, the compressed strength of the sludge mixture can reach 1.8 MPa. Of all the factors that influence the solidifying process, water content is of greatest importance. However, it is an adverse factor to the sludge mixture. When the water content reaches 71.2% , the compressed strength may rise to 2.062 MPa after curing 7 d while the compressed strength may drop to 0. 622 MPa after curing 7 d getting to 79.3 %. In addition, it is also necessary to know that leaching of heavy metals would be less than the tolerable limits. Therefore, it can be concluded that the three decisive measures to solidify the sewage sludge with the above prescription can keep the physical and chemical stabilization of the sludge longer ,for it is the solidification of sewage sludge that helps to immobilize the contaminants from the solidified products, which are supposed to be used in the landfill.