水库疏浚底泥絮凝沉降室内试验研究

摘要

The efficiency of mud flocculation settling is an important factor affecting the dredging progress in lakes or reservoirs.To explore the effect of different flocculants (organic and inorganic) on the settling efficiency of dredged mud,we compared the flocculation settling efficiency and supernate quality of dredged mud treated by organic flocculant (PAM) and five inorganic flocculants(PAC,FeCl3,Na2CO3,Na2SiO3 · 9H2O,and KAl(SO4) 2 · 12H2O),respectively.Furthermore we conducted optimization test on the combination of flocculants to achieve an optimum settling efficiency and supernate water quality.Through the indoor tests we conclude that PAM could effectively promote the flocculation settling of dredged mud soil particles,but the efficiency of reducing turbidity is low;CO32-could also improve the efficiency of flocculation settling by gathering fine particles into large particles;Fe3+ and Al3+ could reduce the turbidity of supernate,but has limited effect in enhancing flocculation settling.The optimum combination of flocculants is 10 ml PAM+2gPAC+2gNa2CO3 in every 1 000 ml dredged mud,which could both accelerate the settling of dredged mud and reduce the turbidity of supernate effectively.%泥浆絮凝沉降效率是影响湖库疏浚工程进度的重要因素.为探索不同絮凝剂(有机、无机)对疏浚泥浆絮凝沉降效率的影响,以通济桥水库疏浚底泥为研究对象,通过室内试验先分析1种有机絮凝剂(PAM)和5种无机絮凝剂(PAC,FeCl3,Na2CO3,Na2SiO3·9H2O,KAl(SO4)2·12H2O)单独作用下疏浚泥浆的絮凝沉降效果及上清液水质的优劣情况,然后对有机、无机絮凝剂进行优化组合试验,确定絮凝沉降效果和上清液水质最优的设计配比方案.试验结果表明:①PAM可以有效促进疏浚泥浆土颗粒的絮凝沉降,但对上清液的去浊率较低;CO2-可以促进细颗粒絮凝结合成大颗粒,提高颗粒的沉降速率;Fe3+,Al3+具有改善上清液浊度的作用,但对促进泥浆絮凝沉降效果有限.②每1 000mL疏浚泥浆中采用10 mL PAM+2 g PAC+2 g Na2CO3的有机-无机絮凝剂组合为最佳方案,既能快速促进疏浚泥浆的絮凝沉降,又能有效降低上清液的浊度.试验成果可为类似疏浚工程中选择絮凝剂最佳配比方案提供参考.