建筑废弃泥浆泥水分离过程与效果评价

Mud-water separation process and performance evaluation of waste slurry from construction engineering

为明确建筑废弃泥浆泥水分离性能,提高泥浆泥水分离效率,选取有机、无机和复合3种化学絮凝方法,通过室内沉降柱、颗粒级配和扫描电镜试验,对比研究絮凝剂类型和投加量对泥浆泥水分离效果的影响及微观作用机理.结果表明:有机和复合絮凝剂可有效促进快速泥水分离,有机絮凝剂按调理效果排序(根据上清液体积高低)依次为阴离子聚丙烯酰胺、聚丙烯酰胺、两性离子聚丙烯酰胺、阳离子聚丙烯酰胺和聚二甲基二烯丙基氯化铵,适宜投加密度阴离子聚丙烯酰胺的泥水分离效果最佳,分离泥浆中水的质量分数小于76.8%;无机絮凝剂的泥水分离效果则相对较差;氯化铁和阴离子聚丙烯酰胺联合投加可以提高泥浆调理效果,有效发挥絮凝剂的电中和及网捕-卷扫作用;絮凝剂通过吸附架桥作用使泥浆颗粒发生明显聚集现象,即细颗粒减少、团聚粗颗粒增加.扫描电镜图显示:原始泥浆颗粒倾向于平行方式沉积,投加絮凝剂使得泥浆颗粒团聚、絮体结构更加致密,揭示了絮凝作用诱发建筑泥浆泥水分离过程的微观机理,为泥浆快速泥水分离技术提供数据支撑和理论依据.

Three chemical flocculation methods including organic,inorganic and organic-inorganic composite were selected to treat slurry from construction engineering,in order to identify the mud-water separation process and to improve the mud-water separation efficiency.The effects of flocculant type(organic,inorganic and composite)and flocculant dosage on the mud-water separation process and its associated micro-mechanisms were compared through the indoor sedimentation column,particle grading and scanning electron microscopy tests.The experimental results show that the organic and composite flocculants can effectively promote the mud-water separation process,and the conditioning effect of organic flocculants is presented as follows according to the value of supernant volume:APAM>PAM>ACPAM>CPAM>HCA.The optimum performance of mud-water separation is identified at reasonable amount of APAM,and the water content of dewatered slurry is less than 76.8%.The effect of inorganic flocculants on mud-water separation is relatively poor,when compared to organic and composite flocculants.The combined formulation of FeCl3 and APAM can improve the conditioning performance of slurry,and play effectively the role of electro-neutralization and net capture-sweep.The flocculant caused an obvious agglomeration of fine particles in slurry through adsorption bridging,leading to a reduction in fraction of fine particles and an increase in amount of agglomerated coarse particles.The scanning electron microscopy images reveal that the original slurry particles tend to be deposited in a parallel manner,and the flocculant induces an agglomeration of fine particles and a denser flocculated microstructure.This study reveals the intrinsic microscopic mechanism of flocculation-induced mud-water separation process,and provides a theoretical basis for rapid mud-water separation technology of waste slurry from construction engineering.