Researsh On Seepage Rule And System Design Of In -Situ Dehydration System

At present, natural drying processing was almost used in dredged sludge dewatering. But both slower sedimentation rate and higher moisture content made dehydrated sludge difficult to transport and utilize.The dredged sludge from Yunnan Dian Lake was used as research object. Effects of permeability rule in dewatering process were investigated by dehydrating agent, filter material, vacuum environment and other factors.The migration and movement law of water in the dredged sludge particles were also discussed. The best dehydration process conditions was determined through the parameters of dredged sludge, such as permeability coefficient, water percolating capacity, permeation rate, moisture content, particle size distribution, water quality and so on.The results showed that the optimum values of WXZ-1, WXF-1, and WXZ-4 were 100mg/kg, 100mg/kg, and 1% of dry sludge, respectively. The better dehydration effect could be achieved. The fastest seepage velocity was obtained by choosing 750-B which was disposed by WXB-2 under oven dried method with fifteen times diluting and three times spraying. Permeability coefficient was increased from 4.68×10-6cm/s to 6.78×10-5cm/s under the mode of loading for 0→20KPa→40KPa→60KPa→80KPa→100KPa gradient pressure variation way for 55-60min. Energy consumption was reduced by 6.7% by using this handing method. The penetrating quality and filtration effect were better, filter cake moisture content reduced obviously and the porosity was increased. The addition of modifier indicated that they could improve the particle size distribution and increase the porosity of porous medium. Moreover, the hydrophilic performance on the surface of filter material was improved by surface modification and i water seepage channel was unchoked at the same time. The reasonable adjustment of load pressure, pressure time and load way would contribute to speed up the penetration. The optimal conditions improved both dehydration rate and degree.In addition, a set of in-situ dehydration device was designed according to experimental data and theoretical parameters. Under the device, the high water content of stock dump sludge, long drying time and large occupied area could be settled. The device was an upsizing and recycling dehydration unit including sludge dehydration, sludge drying, sediment grading and residual water treatment. The characteristics of the device were large processing size, low environmental pollution, short time limit and high economic benefit. The moisture of dredged sludge could be decreased from 85%～95% to less than 50% quickly within 40 days. The sludge volume was compressed to 1/4～1/5 of original sludge to meet the requirements of transportation and resource utilization.