铁修饰的污泥生物炭对污泥脱水性能的改善效果

为改善城市污水处理厂污泥的脱水性能，采用铁修饰污泥生物炭作为助滤剂，与FeCl₃一起对污泥进行联合调理。以污泥净产率、污泥比阻和泥饼含水率评价污泥脱水性能；通过污泥Zeta电位、扫描电镜、EDS和泥饼可压缩性系数分析该方法的机理；同时，通过对污泥胞外聚合物、重金属以及总氯含量的分析，探究其调理污泥的环境风险，以明确该方法用于改善污泥脱水性能的可行性。结果表明，在500 ℃下制备的铁修饰污泥生物炭(30%)和FeCl₃(12.82%)联合调理时，污泥脱水的效果最佳；与仅用FeCl₃(12.82%)调理的污泥相比，污泥净产率升高了73.38%、污泥比阻降低了68.75%、泥饼含水率降低了9.03%。在较高温度下制备的铁修饰污泥生物炭，其孔隙结构更为发达、表面铁元素含量更高；与FeCl₃联合调理污泥时，更容易发生絮凝，从而使泥饼的渗透性能更好。而且，在联合调理的条件下，污泥中溶解型、松散结合型和紧密结合型胞外聚合物的含量均有所降低；污泥泥饼中重金属(Cd、Cr、Cu、Pb、Zn)更为稳定，泥饼热解固相产物和非固相产物中总氯含量降低，环境生态风险更小。采用铁修饰污泥生物炭作为助滤剂，可改善污泥脱水性能，并具有实际应用的潜力。

Iron-modified sludge biochar as a filter aid to improve sludge dewaterability

Iron-modified sludge biochar was used as a filter aid to synergistically improve FeCl3 sludge in municipal sewage treatment plants conditioning and dewatering. Sludge dewaterability was evaluated by net sludge solid yield, sludge specific resistance to filtration and moisture content of sludge cakes. The conditioning mechanism was studied by the analysis of Zeta potential, scanning electron microscope, EDS and coefficient of compressibility of sludge cakes. At the same time, the environmental risk of conditioned sludge was studied through the analysis of extracellular polymeric substances, heavy metals and total chlorine content of sludge, to confirm the feasibility of improving sludge dewaterability with iron-modified sludge biochar. The results showed that the synergetic sludge conditioning with iron-modified sludge biochar(30%)prepared at 500 ℃ and FeCl3(12.82%)presented the best sludge dewaterability, and the net sludge solid yield increased by 73.38%, the sludge specific resistance to filtration decreased by 68.75%, and the moisture content of sludge cake decreased by 9.03%, compared with the sludge conditioning with FeCl3(12.82%)alone. The pore structure of iron-modified sludge biochar prepared at higher temperature was richer, and its surface iron content was higher. When it was used for sludge conditioning combined with FeCl3, leaded to easier sludge particle flocculation and better permeability of sludge cake. Moreover, with the synergetic sludge conditioning, the content of soluble, loosely bound- and tightly bound- extracellular polymeric substances reduced, the heavy metals (Cd, Cr, Cu, Pb, Zn) in sludge cakes were more stable, and the total chlorine content in solid and non-solid pyrolysis products of sludge cake reduced, therefore, the environmental ecological risk was lower. Iron-modified sludge biochar as a filter aid to improve sludge dewaterability had the potential of practical application.