药剂真空预压法处理宁波废弃泥浆试验研究

针对浙江宁波某场地的工程废弃泥浆进行了系列药剂真空预压室内试验研究,基于沉降柱试验确定不同絮凝剂的最佳添加量;按照絮凝剂最佳添加量,进行阴离子聚丙烯酰胺药剂真空预压法的模型试验,探讨药剂真空预压法固液分离的效果;最后,对模型箱中不同位置处的泥样做压汞试验,研究泥样微观孔隙沿径向的分布规律.研究表明:加入适量絮凝剂后,初始上清液浊度较为接近,且浊度随时间变化曲线斜率较大,絮体尚未稳定;24h后浊度曲线斜率较小,絮体达到较为稳定的状态,此时上清液浊度最低对应的絮凝剂添加量为最佳添加量.加入絮凝剂后泥浆颗粒粒径明显增加,大于0.075mm的颗粒由原来的11.78%增加到了79.69%.废弃泥浆絮凝后静置24h后排出上清液含水率从278%降至157%,真空预压136h后从157%降低到了约47.2%,固液分离的效率较高.经过药剂真空预压后,泥浆中孔隙被大大压缩,孔径峰值区域从絮凝后真空前的1 000~120 000nm减小到100~20 000nm,且距离中心越近孔径越小.

Experimental study of Ningbo waste slurry treatment by vacuum preloading with flocculants

Series of vacuum preloading tests with flocculants were carried out in laboratory for construction waste slurry from Ningbo, Zhejiang, the optimum adding amount of flocculants was obtained through sedimentation column tests. Based on the optimum adding amount, model tests on vacuum preloading with anionic polyacrylamide (APAM) flocculants were carried out, and the treatment effects of solid-liquid separation were discussed. At last, the distributing rule of microscopic pores along radial direction was studied using mercury intrusion porosimetry method on slurry pore samples at different locations in the model box. The study results show that the change of supernatant initial turbidity in different adding amounts is not obvious, the slope of the supernatant turbidity curve is larger and the flocculants do not reach steady state. Then, after 24 hours, the curve slope becomes smaller and the flocculants reach steady state at this point, the minimum supernatant turbidity after 24 hours settlement could be an evaluation standard of flocculation effect. Particle size is increased effectively after flocculation and the particles larger than 0.075 mm increase from 11.78% to 79.69%. Moisture content of waste slurry reduces from 278% to 157% after discharging the supernatant by adding the flocculants and settling 24 hours, and reduces from 157% to 47.2% by vacuum preloading further, the efficiency of solid-liquid separation is first preference. After the vacuum preloading stage with flocculants, the pore in the slurry continues to be compressed, the pore size of soil reduces from 1 000- 120 000 nm to 100-20 000 nm, and decreases along with reducing the distance to the box center.