Research On Electro-osmosis Coupling With Ultrahigh Pressure High Dry Dewatering Of Municipal Sludge

In the process of urbanization,the output of domestic sewage is increasing day by day.The accompanying sludge is huge in volume,which has a great impact on the ecological environment.The effect of sludge dewatering is very important to the final treatment and disposal.At present,plate and frame pressure filtration dewatering needs to add a large number of chemicals to the sludge.Belt pressure filtration can only reduce the sludge moisture content to about 80%,which does not meet the final disposal standard of the national sludge.Electro-osmotic dehydration technology is clean and efficient,without adding any chemicals,but the technology is not mature enough to be widely used in industry.Aiming at the difficult problem of municipal sludge dewatering,this paper puts forward the electro-osmosis coupled with ultra-high mechanical pressure for sludge dewatering research,which reduces the water content of sludge.We independently design and process the electro-osmotic dewatering device,design the constant voltage gradient control system,and measure the sludge thickness in real time,so as to realize the constant voltage gradient in the whole process of electro-osmotic dewatering.The effects of initial sludge thickness,voltage,voltage gradient and mechanical pressure on electro-osmotic dewatering were studied under MPa mechanical pressure.The experimental phenomena and results were analyzed and validated.Then the orthogonal design was carried out on the basis of the experimental results to confirm the order of influence of each parameter on dehydration effect.The selection of each experimental parameter value in the single factor experiment refers to the parameter variation interval that the experimental device can provide.The final parameter selection value is determined according to the analysis and some preliminary experiments.Constant voltage gradient and constant voltage experiment was carried out and compared by using constant voltage gradient control system.On the basis of experiments the variation of sludge resistance,loop current,sludge thickness and power consumption during electroosmosis were analyzed.The variation of sludge resistance under different voltage was compared.And calculate the corresponding compression ratio by the change of sludge thickness with time.The energy consumption and loop current in the two electroosmotic dehydration modes are compared,and the experimental data are analyzed to draw corresponding conclusions.A mathematical model of electro osmotic dehydration under ultra-high mechanical pressure is established by designing response surface experiments.The reliability and accuracy of the model were determined by variance analysis,significance test and error analysis.Finally,the optimum solution of the model is obtained by setting parameters.