新型复合絮凝剂对疏浚底泥脱水和重金属固化的研究

模拟实际工程条件, 在实验室考察3种化学调节剂(聚合硫酸铁(PFS)、聚丙烯酰胺(PAM)和一种自配的复合絮凝剂(S003))对实际污染河流底泥的脱水效果。结果表明, 使用PFS和PAM处理后, 泥饼含水率分别为60.22%和64.77%; 用S003处理后, 泥饼的含水率为52.67%; 与PFS和PAM相比, S003处理的脱水速度更快, 具有更好的除浊效果。S003优良的脱水效果主要是由于其含有的无机成分的骨架作用和有机成分的桥接作用, 使底泥形成多孔结构的大絮体, 加快底泥沉降速度, 提高了底泥过滤性能。此外, 受污染的疏浚底泥经S003固化后, 固化体中Cr, Cu, Zn, Ni, Pb和Cd的浸出浓度分别减少55.8%, 92.1%, 89.2%, 61.4%, 34.2%和56.3%。研究结果表明, S003对底泥具有高效的脱水作用和重金属良好的稳定效果。

Study on New Composite Flocculants in Dewantering of Dredged Sediments and Solidification of Heavy Metals

The chemical conditioners polymerized ferrous sulfate (PFS), poly(N-isopropyl-acrylamide) (PAM) and a self-made compound flocculant (S003) were used to investigate the dewatering effect on the actual polluted river sediments by simulating actual engineering conditions in the laboratory. The water content of dewatered cakes was 60.22% and 64.77% in the sediment conditioned with PFS and PAM, while the water content was 52.67% with S003. Compared with PFS and PAM, S003 achieved a faster settling rate and removed more turbidity. S003 achieved the best dewaterability of sediments because it had inorganic composition as sediments skeleton and organic compounds with bridging effect, contributing to form large dense flocs with porous structure, which speeded up the sediment settling rate and improved the filtration performance of sediments. In addition, the leaching rates of Cr, Cu, Zn, Ni, Pb and Cd in the solidified products were reduced by 55.8%, 92.1%, 89.2%, 61.4%, 34.2% and 56.3% respectively after conditioning with S003. It demonstrated that S003 greatly improved the sediment dewateribility and had excellent stabilizing effect on heavy metals.