电解质对三峡库区泥沙Zeta电位及絮凝特性影响

三峡库区泥沙淤积及水环境问题一直被广泛关注,泥沙淤积量对入库泥沙量的占比逐年增大,对于通航、水库调水防洪能力、生态环境保护等都造成了负面影响.三峡库区泥沙淤积的主要原因是因为发生了絮凝沉降,而泥沙絮凝又与诸多因素有关,其中电解质是影响较大且较为复杂的因素.采用了一套自研的多层格栅絮凝沉降装置,通过多层格栅上下振动产生近似各向同性均匀紊流,来模拟三峡库区自然流态下泥沙的絮凝过程,并且分析在不同浓度的Nacl、MgCl2、CaCl2、AlCl3溶液中库区泥沙Zeta电位及絮凝特性的变化.结果表明:加入电解质可以改变泥沙颗粒的Zeta电位,并且随电解质浓度的增加,泥沙颗粒电位绝对值降低;4种电解质均可对三峡库区泥沙的Zeta电位造成影响,但不同价态及不同种类的离子对于Zeta电位的影响也有所不同;在动态水流条件下,电解质的投入对泥沙絮凝起明显的促进作用,并且这种促进作用同样与电解质种类有关.

Study on the Influence of Electrolyte on Zeta Potential and Flocculation Characteristics of Sediment in the Three Gorges Reservoir Area

The problems of sedimentation and water environment in the Three Gorges Reservoir area have been widely concerned. The proportion of sedimentation in the amount of sediment entering the reservoir has been increasing year by year, which has caused negative impacts on navigation, reservoir water transfer and flood control capabilities, and ecological environment protection. The main reason for the sedimentation in the Three Gorges Reservoir area is the occurrence of flocculation and sedimentation, and the flocculation of the sediment is related to many factors, among which electrolyte is a more influential and more complex factor. A set of self-developed multi-layer grid flocculation and settling device was used to generate approximately isotropic and uniform turbulent flow through the up and down vibration of the multi-layer grid to simulate the flocculation process of sediment in the natural flow state of the Three Gorges reservoir area. And analyze the changes of sediment Zeta potential and flocculation characteristics in different concentrations of Nacl, MgCl2, CaCl2, AlCl3 solutions. The results show: (1) Adding electrolyte can change the zeta potential of sediment particles, and with the increase of electrolyte concentration, the absolute value of sediment particle potential decreases; (2) The four electrolytes can all affect the Zeta potential of the sediment in the Three Gorges Reservoir area, but different valence states and different types of cations have different effects on the Zeta potential; (3) Under dynamic water flow conditions, the input of electrolyte can obviously promote sediment flocculation, and this promotion is also related to the type of electrolyte.