前置沉降对城市河道淤泥电渗脱水的影响

针对河道淤泥电渗脱水过程中存在的高能耗现象,以城市河道淤泥为实验对象,通过预设自由沉降辅以水平环形电场的电渗脱水方式,以出水速率,脱水终点时间、淤泥含水率、能耗为评价指标,就预沉时间与电压大小对淤泥的脱水效率进行了实验研究。结果表明:预沉60min、电压梯度为4V/cm、持续电渗270min,淤泥含水率由97%下降到75.9%;其中电渗环节含水率由92.5%下降到75.9%。达到脱水终点时,预沉电渗脱水时间较直接电渗脱水延长10%、而干泥能耗则由直接电渗脱水的8.67(kW·h)/t下降到4.25(kW·h)/t,下降比例为51.04%。前置沉降有效脱除淤泥中存在的自由水分,从而为后继电渗脱水环节的节能奠定了基础。

Effect of Presettling on Electroosmotic Dehydration of Silt in Urban River

To relieve the high energy consumption in the process of dewatering for river sediments by electroosmosis process, the electroosmosis modified by annular electric field was used to treat the river sediments after a presettling time. The effect of voltage and presettling time on the dewatering efficiency were studied by the assessment of dewatering rate, dehydration-end-point, sludge water content and energy consumption. It indicated that the sludge water content decreased from 97% to 75. 9% by continuous electro-dewatering 270 min on voltage gradient of 4 V/ cm after 60 min of presettling. In the electrosmosis process, the water content was decreased from 92. 5% to 75. 9%. Compared with the traditional electroosmosis for treating river sediments, the time for reaching the dehydration-end-point in modified electroosmosis process was prolonged by 10%, however, the energy consumption was decreased by 51. 04% from 8. 67 (kW·h)/ t to 4. 25 (kW·h)/ t for the dried sludge. The presettling process can effectively remove the free water in the silt, thus laying a foundation for the energy saving in the later stage of electroosmosis and dehydration.