CaPFS调理反应时间对河道底泥电渗脱水的影响

Effect of Conditioned Reaction Time by CaPFS on Electro-dewatering for River Sediment

针对河道疏浚底泥采用电渗脱水时能耗高、脱水时间长,不利于其工程应用推广的问题。采用自制的钙基聚合硫酸铁(CaPFS)对起始含水率为68%±0.5%的河道底泥进行调理后电渗脱水,重点考察了调理反应时间对脱水速率、电极电流、泥饼电阻及脱水能耗的影响。结果表明:添加CaPFS调理反应10 h,采用20 V的垂直电场进行脱水时,(75±3)min泥饼脱水即达到终点,此时底泥含水率由68%±0.5%降至59.8%±1.6%,脱水速率为(0.38±0.06)g/min,脱水能耗为(118.7±2.4)kWh/t滤液,未CaPFS调理时,脱水能耗为(156±3.5)kWh/t滤液、达到终点脱水时间为(110±2)min。分析脱水过程电化学行为与泥饼脱水关系可发现,当CaPFS加入后,Ca和Fe共同作用压缩颗粒表面双电层促进了颗粒再聚集,减少了颗粒间空隙,从而迫使自由水渗出。可见,CaPFS的调理有效缩短底泥电渗脱水时间、提高脱水能效,为电渗脱水技术在河道底泥治理工程中的应用与推广提供了理论与技术的支撑。

In order to solve the problems of high energy consumption and time-consuming of electroosmosis dewatering for dredged river sediment,it is not conducive to its engineering application and popularization.Calcium-based polyferric sulfate(CaPFS)was used for conditioning and dewatering the river sediment with an initial water content of 68%±0.5%.The effects of conditioning reaction time on dewatering rate,electrode current,mud cake resistance and energy consumption were investigated.The results showed that when CAPFs were added for 10 h and 20 V vertical electric field was applied for dehydration,the end point of sludge cake dehydration was reached in 75±3 min.The water content of sediment decreased from 68%±0.5%to 59.8%±1.6%,the dehydration rate was 0.38±0.06 g/min and the dehydration energy consumption was 118.7±2.4 kWh/t filtrate.However,for those without CaPFS conditioning,the energy consumption was 156±3.5 kWh/t filtrate and the dehydration time to the end point was 110±2min..By analyzing the relationship between the electrochemical behavior and the mud cake dehydration during the dehydration process,it was considered that after the CaPFS was added to conditioning,Ca and Fe compressed the electric double layer on the surface of sediment particles for a certain time to promote particle re-aggregation,reduced the inter granular space,thus forming comfortable conditions for free water to be extruded.It can be seen that the conditioning of CaPFS can effectively shorten the time of electroosmosis dewatering for dredged river sediment and improve the energy efficiency of dehydration,which provides theoretical and technical support for the application and promotion of electroosmosis dewatering technology in river sediment treatment projects.