Study On The Mechanism Of Flocculation-Electroosmosis-Vacuum Preloading Treatment Of Sludge

In China,as river dredging has gradually become the norm,the amount of silt produced by river dredging is huge,and the sludge dewatering treatment is difficult.An efficient treatment method is urgently needed.Therefore,electroosmotic vacuum preloading technology has become the focus of research.The electro-osmotic vacuum preloading technology also has some shortcomings.In view of the shortcomings of uneven reinforcement and high energy consumption in the process of electro-osmotic vacuum preloading,the use of flocculant to pretreat sludge can improve these shortcomings and improve the efficiency and effect of sludge treatment.Therefore,it is necessary to study the influence mechanism of flocculant on electroosmotic vacuum preloading treatment of sludge,and provide scientific guidance for practical application.In this study,the change mechanism of sludge treated by flocculation electroosmotic vacuum preloading was explored by means of experiment and numerical simulation.Starting from the selection of flocculants and flocculation mechanism,five flocculants were selected for comparison,namely Fe Cl₃,PAC,APAM,APAM-Fe Cl₃（composite）,APAM-PAC（composite）.According to the sedimentation column test,the optimal mixing ratio of single flocculant and the optimal mixing ratio of composite flocculant were determined,and the pore size distribution evolution of sludge treated with the optimal dosage of flocculant was compared and analyzed by nuclear magnetic resonance instrument.The improved Miller Soil Box device was used to measure the electrical conductivity and electrical permeability coefficient of sludge before and after treatment,and the change mechanism of electric parameters during flocculation was revealed.The sludge test of organic flocculant and inorganic flocculant combined with electroosmotic vacuum preloading was carried out respectively,and the effect of organic flocculant and inorganic flocculant on sludge drainage consolidation treatment was compared.When vacuum preloading is carried out alone,the effect of Fe Cl₃ and APAM is not much different;after adding electroosmotic,since the flocculation of Fe Cl₃ mainly depends on electric neutralization,with the discharge of ions and the formation of compounds,electroosmotic effect will be gradually weaker than APAM.However,it can be found that both Fe Cl₃ and APAM can effectively increase the effective voltage in the electroosmotic process,thereby greatly improving the electroosmotic treatment effect.The electroosmotic vacuum preloading tests of organic flocculant,inorganic flocculant and composite flocculant were carried out.The changes of soil current,settlement and pore pressure during the test and the water content and shear strength of soil after the test were tested.According to the theory and numerical model studied by previous scholars,the numerical simulation is carried out,and the changes of soil settlement,potential and pore pressure during the test are compared.Finally,a numerical model considering the nonlinear change of soil parameters is established.After analysis,the calculation results of the model are consistent with the actual test results.Therefore,such numerical simulation methods can be used to predict the test better,so as to save a lot of time and improve the efficiency of work.In this paper,the mechanism of electroosmotic vacuum preloading combined with inorganic flocculant,organic flocculant and composite flocculant is revealed,and the formula of composite flocculant suitable for river silt treatment is provided.The numerical simulation method of electroosmotic composite vacuum preloading is given,which provides scientific guidance for dredging silt treatment.Figure 82 Table 8 Reference 97...