透光脉动检测仪研究碱度对絮体形成、破碎及再生的影响

Study on the influence of alkalinity on floc formation,breakup and regrowth by photometric dispersion analyzer

为了解碱度对絮体的形成、破碎及再生过程的影响,采用PDA2000型透光脉动检测仪测定不同碱度下投加硫酸铝时高岭土悬浮液的絮凝指数(FI指数),并以强度因子和再生因子评价絮体的强度和再生能力。结果表明,碱度的高低在很大程度上会影响絮体的形成、破碎及再生过程,所形成絮体的颗粒随碱度的增加而减小。混凝剂投量和碱度高低共同决定了絮体的抗破碎强度,碱度越高,混凝剂投量越大,絮体的强度越高。在电中和作用下形成的絮体在低碱度下经一次破碎后恢复程度接近100%,在网捕卷扫作用下形成的絮体,无论碱度高低,从第2次破碎起,FI指数均以大于10%的幅度逐次下降,絮体不可恢复程度显著增大。

In order to find the influence of alkalinity on the formation,breakup and regrowth of flocs,photometric dispersion analyzer （model PDA2000） is applied to investigate flocculation index （FI index） of flocs formed by kaolin suspension with aluminum.The strength factor and the regrowth factor are used to evaluate the flocs strength and the regrowth of broken flocs.The results shows that the formation,breakup and regrowth process of flocs are affected by alkalinity to a great extent,and the floc particle diameters reduce with the increase of alkalinity.The flocs strength is determined by both coagulant dosage and alkalinity.The flocs strength becomes higher,when higher alkalinity and more coagulant dosage are added.The regrowth degree of flocs formed mainly with charge neutrality action is approached about 100% in the first breakup process under low alkalinity.For the flocs resulted mainly from sweep coagulation action,the FI index is reduced with more than 10% degree each time from the second breakup process and the flocs strength is reduced remarkably without relation to alkalinity.