聚合硫酸铁(PFS)混凝腐殖酸(HA)的过程中典型操作因素的影响研究

针对聚合硫酸铁（PFS）混凝-沉淀去除腐殖酸（HA）水样的过程,通过测定典型操作因素（PFS投加量、原水pH和搅拌方式）下微絮体的zeta电位、上清液的浊度、UV254、pH值及电导率和絮体沉降体积变化,探讨了这些因素对该过程的影响.结果表明：在原水pH=6.00时,PFS混凝HA的主要机制为电中和作用,搅拌方式对PFS的最佳投加范围没有明显的影响,但单一搅拌方式下HA的去除效果更好;在原水pH=8.00时,吸附络合-卷扫絮凝成为主要的混凝机制,复合搅拌方式下PFS的最佳投加量范围大于单一搅拌方式,且前者的HA去除效果更好.整体而言,几种混凝条件下PFS最佳投药量对应的微絮体zeta电位均在-12.00mV左右;原水pH=6.00时PFS混凝-沉淀去除HA的效果比原水pH=8.00时的好,且前者形成的PFS-HA沉淀絮体体积较小,但单一搅拌方式下絮体结构的重组过程并不是影响絮体体积的主要因素.复合搅拌方式中开始阶段的高强度搅拌有助于PFS组分在HA水样中的分散而有利于其电中和作用的发挥,但对PFS的水解过程影响不大.

Study on the effect of typical operating factors on the coagulation of humic acids with polymeric ferric sulfate

The effect of typical operating factors, such as initial pH of HA solution, poly-ferric sulfate (PFS) dose, and way of mixing, on humic acid (HA) removal with a coagulant of PFS was studied. The changes in the zeta potentials of micro-flocs, turbidity, UV₂₅₄ absorbance, pH and conductivity of supernatant, and the volume of flocs were analyzed. The results showed that the charge neutralization mechanism played an essential role in HA coagulation at an initial pH of 6.00. The way of mixing had no obvious effect on the optimum PFS dosage range, while one-stage mixing in coagulation-flocculation process led to a higher HA removal ratio than two-stage mixing. When the HA solution was coagulated at an initial pH=8.00, absorption-complexation and flocs sweeping became the main coagulation mechanism. Two-stage mixing exhibited wider optimum PFS dose range for HA coagulation and higher HA removal effect than one-stage mixing. Generally, the zeta potentials of micro-flocs were about -12.00 mV at the optimum PFS dosage for HA removal. Moreover, a better effectiveness on HA removal and a smaller volume of PFS-HA flocs were found at an initial pH of 6.00 than 8.00. It can be determined that re-organization of the PFS-HA flocs with one-stage mixing was not a significant impact factor on the volume of the flocs. In addition, the stronger agitation in the first stage of the two-stage mixing favored charge neutralization mechanism due to fast transportation and dispersion of PFS species in HA solutions, while it had no effect on the hydrolysis of PFS.