水热处理时间对污泥中氮磷钾及重金属迁移的影响

Effects of Hydrothermal Treatment Time on the Transformations of N,P,K and Heavy Metals in Sewage Sludge

研究了水热法预处理城市污泥时反应时间对污泥脱水性能和污泥中N、P、K元素及重金属迁移行为的影响.结果表明,在160℃的温度下,随着水热反应时间（30~120 min）的增加,污泥脱水性能明显提高,污泥中的N元素向水热液中转移量逐渐增加,P元素几乎全部残留在固相中.虽然K元素较P易转移到液相中,但多数K元素（57%~62%）还是残留在污泥固相中.重金属的迁移和元素本身的性质有关,其随着水热处理时间的增加而呈现出不一致的迁移规律：相对于原污泥,Cu、Zn、Cr和Pb的含量在脱水污泥中增加程度明显,As增加缓慢,而对于Ni和Cd则先低于原污泥中重金属含量,而后随着水热处理时间的延长不断增加.

Hydrothermal treatment（ HTT） of sewage sludge was conducted, focusing on the influence of HTT time on the dewaterability of sludge and transformations of elements N,P,K and heavy metals. The results showed that at a hydrothermal temperature of 160℃,with HTT time increasing from 30 to 120 min,the sludge dewatering performance was significantly improved.The transfer rate of N element in the sludge transferring to aqueous product increased gradually. Almost all of P element remained in the solid phase,and most of K element（ 57%-62%） was still in the solid phase although it was more easily transferred to the liquid phase than P element. The transferring behavior of heavy metals during the HTT related to their own properties,and their transferring behaviors were different with the increase of HTT time. Compared with the raw sludge,the contents of Cu,Zn,Cr and Pb in the dewatered sludge increased significantly,As increased slowly,while Ni and Cd were first lower than those in raw sludge,and then increased with the prolonging HTT time.