长期运行均质滤料性能下降原因及恢复研究

Reason for Performance Deterioration of Long‑term Operating Homogeneous Filter Media and Recovery Measures

针对西北地区某水厂均质滤料滤池出水浊度偏高、截污能力下降问题,以性能下降明显的滤池为研究对象,在中试滤柱系统中对旧砂和新砂滤料的除浊性能进行了评价。结果表明,在同一运行条件下,旧砂滤柱出水浊度比新砂滤柱高0.2 NTU左右。滤料的特性测定结果显示,旧砂与新砂最大的区别是滤料级配和细砂占比的不同。进一步对比了装填旧砂、补充细砂后的旧砂、两种不同粒径级配的新砂等4个滤柱系统对浊度和颗粒物的去除效果。结果显示,级配相同但表面性质不同的滤料对浊度和颗粒物具有相同的去除效果,这说明旧砂过滤性能下降的主要原因是滤料级配发生了变化,根据级配缺失进行补砂可以恢复滤料的过滤性能。

Aiming at the issues of high effluent turbidity and the reduced pollution interception capacity of homogeneous filter media in a water treatment plant located in Northwest China,the turbidity removal performance of old sand and new sand filter media were evaluated in a pilot filter system,focusing on the filter with obvious performance degradation.Under the identical operating conditions,the effluent turbidity of the old sand filter was approximately 0.2 NTU higher than that of the new one.The test results of the filter media characteristics demonstrated that the most significant disparity between the old sand and the new sand lay in the gradation of the filter media and the proportion of fine sand.The removal efficacies of four filter systems,packed with old sand,old sand supplemented with fine sand,and two new sands with distinct particle size gradations,were further compared.The filter media featuring the same gradation yet distinct surface properties exhibited the identical removal efficacy on turbidity and particulate matters,which implied that the principal cause for the degradation of the filtration performance of the old sand lay in the alteration of the filter media gradation,and the filtration performance of the media could be restored through sand filling in accordance with the loss of gradation.