污泥中重金属的去除及回收试验

论述了利用离子交换技术循环使用柠檬酸去除污泥中重金属,并置换回收重金属的适宜工艺条件.经柠檬酸处理后,污泥中90%以上的重金属被去除;柠檬酸处理液中的重金属用离子交换法回收,考察了树脂种类、流速、操作方式等因素对离子交换、再生效果的影响;在适宜工艺条件下,重金属的交换率均为100%,而洗脱率均接近90%;柠檬酸及离子交换树脂循环使用,重金属也得到回收,降低了处理成本.

Removal and recycle of heavy metals in sludge

Heavy metals in wastewater treatment sludge were first extracted by citric acid and subsequently removed from the citric acid by ion exchange.They were recovered from the ion exchange bed by dilute HCl and,finally,were replaced in the spent HCl by Al to form valuable water treatment coagulant and recycleable metals.The effects of resin types,flow rate and flow pattern on the IX treatment and regeneration were determined.Using 0.2 M citric acid at pH of 3.0,more than 90% of the heavy metal content was extracted in 24 hours;the metal removed sludge could be used as a natural fertilizer.The least costly 732 cationic resin performed the best among the four cationic IX resins studied;nearly 100% of heavy metals in the citric acid feed were removed and that regeneration recovered more than 90% of those removed.The process employing citric acid for sludge extraction,732 cationic resin for removing the metal in the citric acid,3 bed volumes of 5% HCl for resin regeneration,and Al slices for replacing the recovered heavy metals in the spent HCl is a low cost method(YMB$35/ton dry sludge) for removal and recycle of heavy metals in the sludge.