| In some part of the coastal area of our country, the properties of dredger fill is mianly about soft soil, like muddy soil. Foundation made by this kind of soil needs to go through a certain period of time to settle by gravityand mechanical processing to meet the use requirements, so it is difficult to apply this foundationquickly. Some curing methods, such as adding cement and lime, are widely used at home and abroad, but they are long construction period, high cost, and difficult to achieve the ideal effect. In recent years, some scholars’ research shows that, adding flocculationto muddy soilcan effectively reduce the thickness of the bound water layer on the particle’s surface, improve the settling velocity and discharge capacity.However, the study on dredger fill with flocculation treatment in coastal area is less.This paper chose organic polymers polyacrylamide and inorganic polymeric aluminum chloride to flocculate with mucky dredger fill in Tianjin and Lianyungang. Added high molecular weight CPAM, APAM, NPAM, PAC, "organic-inorganic " mixed flocculation, observed experiment phenomenon and determine Zeta potential, flocculated micelles’ size, water content of sludge cakeon the surface of colloidal particles in the mud. According to the charge neutralization, bridge and sweeping function of flocculation, analyzedevery flocculation’s effect on dewatering capability of mucky dredger fill.Based on DLVO theory, flocculate dagglomeration effectand dewatering capability, determined the optimum adding amount, summarized the relationship among Zeta potential, flocculation effect and dewatering ability of flocculation, discussed the feasibility of Zeta potentialas a dewatering capability evaluation standard of mucky dredger fill.Dewatering tests’ results of mucky dredger fill in the twoareas show that, all ionic polyacrylamide, poly aluminum chloride and organic-inorganic composite flocculation can have effect on mucky dredger fill in the two areas, effectively reduce the water content of sludge cake, change the state of supernatant, improve the settling velocity and increase the colloidal sizeinmud. After adding flocculation, thetrend of water content of sludge cake after dewateringand Zeta potential’s variety of mud particlesin the two areas is similar. This dewatering test of mucky dredger fill incoastal area is representative. Organic-inorganic composite scheme is feasible, after adding some certain polymerization aluminum chloride, the variety of Zeta potential andability of reduce water content of sludge cake is significant. Compared to the single doped CPAM test, PAC and CPAM combined test, water content of sludge cakein Tianjin and Lianyungang respectively reduced from 83.3%, 74% to 83.1%,73.3%. Compared to the single doped NPAM test, PAC and NPAM combined test, water content of sludge cake in Tianjin and Lianyungang respectively reduced from 116.8%, 93.7% to 96.6%,92.8%. PAC can effectively reduce the amount of CPAM and NPAM when gets the same dewatering effect as single doped test. Based on the comprehensive consideration of the charge neutralization and bridge function, should relatively reduce the dosage of PAC.Experimental results show that the flocculation effect of mud is optimal. Mostly, when the Zeta potential values close to zero, Zeta potential value is feasible to be the flocculation effect evaluation index.We believe that the ideal flocculation potential’s absolute value interval in the two areas is0~3.314. When the potential is close to zero, it is not the lowest water content of sludge cake, but the Zetapotential still has a strong influence on the dewatering capability of mud, it is almostfeasible to use this parameter to evaluate the dewatering capability of mud. When added with CPAM and NPAM, Zeta potential’s idealinterval of dewatering capability of mud respectively is-6.906~4.596,-5.246~3.692. |
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