疏浚土排水固结过程中水质分析与污染性评价

为了分析疏浚淤泥排水固结过程中水质的污染特点,首先分析了土样的粒径组成及变化规律,了解其颗粒在渣场内的分选落淤特点,然后测试了水中各种有机、无机污染物的浓度及其变化过程。研究表明,疏浚土以粉粒、黏粒为主,比表面积大,吸附能力强;堆泥场内设置溢流堤、纵向隔堤,形成一定水头差的环形流道,从而有利于颗粒的落淤分选和污染物的吸附悬浮。水体、悬浮物和污染物等在负压抽吸作用下汇集进入排水管网而迁移排出。水质pH值变化很小,符合地表水质量标准;真空预压法可阻隔、过滤、吸附悬浮物、污染物,降低SS值,有利于氮的溶解、富集,总氮(TN)浓度变化不大;管道阻隔吸附、尾水沉淀、水生植物过滤等处治工艺对磷的溶解、吸附效果好,总磷(TP)减少,总溶解磷(TDP)增大,排放的余水中总磷(TP)未超湖、库Ⅲ类水质标准值;水质污染综合指数由基本合格提升为合格。

Analysis of water quality and evaluation of water pollution during drainage and consolidation of dredged sediment

We carried out a series of tests to analyze the water pollution characteristics in drainage and consolidation process of dredged sludge. We first analyzed the grain proportion and its variation law of the soil sample, and studied the sedimentation and sorting features of particles in the dredge disposal site. The concentration and variation law of organic and inorganic pollutants in the drainage water were tested and studied. The studies show that the dredged soil, with larger specific-surface area and strong adsorption ability, is mainly composed of silt and clay. In the disposal site, an annular flow with differential head is formed by arranging overflow dam and longitudinal separation levee, which is conducive to the sorting and sedimentation of the particles as well as the adsorption of contaminants. Under the vacuum negative pressure suction, the drainage water, suspended solids and pollutants are sucked out to pipe network. Water pH change fluctuation is small, which meets the quality standards for surface water. The vacuum preloading technique can block, filter and adsorb suspended solids and pollutants and reduce SS value. Also the vacuum negative pressure suction is favorable for nitrogen dissolving and enrichment, but exerts little effect on total nitrogen (TN). Techniques like pipeline blocking adsorption, tail water precipitation and aquatic plant filter are effective to phosphorus dissolution and absorption, so the total phosphorus (TP) is decreasing and total dissolved phosphorus (TDP) is increasing, and total phosphorus (TP) in the discharge water is not worse than Ⅲ standard of lake and reservoir water. The water pollution index has been improved from nearly qualified to fully qualified.