水力吸泥-离心脱水疏浚过程的环境特征分析

城市建成区的中、小河道底泥污染特征为重金属和有机污染富集于浮动性表层底泥中，以水力吸泥－离心脱水组合疏浚工艺用于清理此种底泥的环境特征分析，采用现场疏浚操作时，同步进行相关物流与水体采样监测的方法进行，结果显示：水力吸泥的疏浚泥浆其污染物组成与原状底泥一致；泥浆经离心脱水后，805以上的颗粒物可回收于含固率谪于70％的脱水泥饼中；脱水泥饼颗粒物的污染程度显著低于原状底泥；离心上清液浓缩了底泥中的各种污染物，其直接排入河道是造成水力疏浚过程水体水质损害的最主要因素；离心上清液可经混凝－澄清－过滤过程有效地净化，研究证明该组合疏浚工艺配套离心上清液澄清后，可符合相关类型受污梁底泥疏浚的环境保护要求，且大部分疏浚物流可就地利用于浸地或农田。

Environmental Characteristic Analysis of Hydraulic Suction- centrifugal Dewatering Dredging Process

The contamination of sediments in the urban rivers of Shanghai is primarily characterized by the enrichment of both heavy metals and organic contaminants in the upper floating layer of sediments.This paper analyzes the environmental characteristics of the hydraulic suction-centrifugal dewatering dredging process,which was applied to clean up the sediments.Monitoring of the dredged material streams and the river water qualities was conducted.The research results indicated that,1) the contaminant composition of the dredged slurry was similar to the in-situ sediments,2) through centrifugal dewatering,about 80% of the particulate matters in the dredged slurry were recovered in the form of dewatered cakes with solid content above 70%,3) the contamination of the cakes was greatly slighter than that of the in-situ sediments,4) direct discharge of the centrate from the dewatering process into the river had predominant adverse effects on the river water quality,due to the enrichment of contaminants in the centrate,and 5) the centrate could be decontaminated through a coagulation-clarification-filtration process.It was proved that the dredging process followed by decontamination of the centrate can efficiently clean up the contaminated sediments in an environmentally sound manner,and the most of the dredged materials,such as the dewatered cakes,can be beneficially used in green areas or farmlands.