铁盐调理联合真空预压法填埋污泥排水加固试验

Experiment on drainage reinforcement of landfill sludge by iron salt conditioning combined with vacuum preloading method

摘要:

针对目前中国多地污泥填埋库库容已严重不足的现状,为恢复库容并加固坑体,采用FeCl₃对上海某污泥填埋库区的填埋污泥进行调理改性,并进行真空预压排水加固试验.试验过程中,对污泥的累计排水量、累计沉降量进行记录,试验后分别进行含水率、十字板剪切强度和压汞试验.结果表明:直接采用真空预压法对原状污泥进行深度脱水的效果有限,经FeCl₃调理改性后污泥脱水性能改善,排水速率加快,排水量增加,试验后平均含水率由75.8%降至66.6%;真空预压后污泥的含水率和抗剪强度分布不均,越靠近排水板变化越大,含水率沿径向和深度方向逐渐增大,抗剪强度沿着径向和深度方向逐渐减小;调理污泥在真空预压后,孔径主要分布在200~100 000 nm,小孔占比最高,其次是中孔,且离排水板越近,大孔越多,微孔越少; 调理后污泥含水率和体积分别减小了9.2%和28.8%,强度提升了10倍. 表明铁盐联合真空预压对污泥处理效果较好,可从优化药剂组合和真空预压工艺参数两方面进一步提升脱水减容效果.

Abstract:

The storage capacity of sludge landfills in some places in China is seriously inadequate. To restore the storage capacity and reinforce the pit body, the experiment of vacuum preloading drainage reinforcement of landfill sludge conditioned by FeCl₃ was carried out. The accumulative drainage volume and accumulative settlement of the sludge were recorded, and moisture content test, vane shear test, and mercury intrusion porosimetry were carried out after the experiment. Results show that the effect of deep dewatering of the sludge by vacuum preloading method was limited. After chemical conditioning, the dewatering performance was improved, the drainage rate and drainage volume were increased, and the average moisture content was reduced from 75.8% to 66.6%. After vacuum preloading, the distributions of moisture content and shear strength were uneven, and the closer it was to the drainage board, the greater the change was. The moisture content increased gradually along the radial and depth directions, while the shear strength gradually decreased. The pore diameter of the conditioned sludge was mainly distributed in the range of 200-100 000 nm. The proportion of small holes was the highest, followed by that of the middle holes, and the closer it was to the drainage board, the more the large holes were, the fewer the micropores were. The moisture content and volume of the sludge decreased by 9.2% and 28.8% respectively, and the strength increased by ten times, indicating that the proposed method had better treatment effect. The dewatering and volume reduction effect can be further improved by optimizing agent combination and vacuum preloading process parameters.