污泥不同脱水方法的实验分析及脱水机理探讨

Dewatering mechanism and experimental analysis of sludge under different dehydration methods

为进一步认识污泥脱水的机理,寻找更为有效的污泥脱水方法,提出了一种新的污泥中水分存在形式的划分方法,同时进行了自重、离心、盐溶液渗析脱水3种实验,并利用光学显微镜和扫描电镜等手段,对原状污泥与3种脱水后污泥的微观结构进行形态学及定量分析。自重、离心、盐溶液渗析脱水后污泥的最终含水率分别为89.4%、78.0%、28.4%,且不同脱水方式会影响污泥的微观结构,进而影响脱水效率;污泥中微生物、絮团、褶皱、裂隙及物质成分等方面是污泥中水分难以脱除的重要原因。污泥在不同的脱水阶段,水分的存在形式不同,脱水的难易程度也不同;脱水程度越高的脱水手段,其脱水后污泥的结构越紧密,孔隙率及等效孔径明显降低,可通过减小污泥内部孔隙的方式进一步提高脱水效率。

The objective of this paper was to explore the mechanism of sludge dewatering and find a more effective method for it. The distribution of water in sludge was re-classified. Then an experimental study was performed to better understand different mechanisms of dewatering methods including self-weight dehydration, centrifugal dewatering and salt solution dialysis. The microstructure of the raw sludge was first characterized by optical microscope and scanning electron microscope. The structure of the sludge dehydrated by different dewatering methods was quantitatively analyzed and compared. The results showed that the final moisture content of the sludge after dewatering by self-weight, centrifugation,and salt solution was 89.4%, 78.0%, and 28.4%. And different dewatering methods affected the microstructure of the sludge, which affected dewatering efficiency. The microorganism, floc, folds, cracks and material composition were the important factors that affect the dewatering effect. The forms of water in sludge is different in different dewatering stages,which lead to the different degree of dehydration. By applying the dewatering method that has a higher efficiency, the sludge exhibit a denser structure and smaller porosity and equivalent pore-diameter. The dewatering efficiency can be increased by reducing internal pores of the sludge.