聚合铝水解形态对混凝效果及絮体特性的影响

Effect of PAC hydrolysis species on coagulation efficiency and floc characteristics

采用微量滴定法制备不同碱化度的聚合铝,并测定其铝形态分布,通过其对腐殖酸-高岭土水样进行烧杯实验,依据絮体的Zeta电位、浊度、UV254及絮体强度因子及恢复因子等参数,以综合评价聚合铝水解形态的混凝机理及其絮体特性。结果表明:聚合铝投加前后铝形态分布存在很大差异,碱化度越低影响越明显,碱化度为0.5的聚合铝中Ala含量由原来的69.57%变为4%左右,而其Alc由9.36%变为50%左右;预制铝的中聚体和高聚体形态在混凝过程中相对比较稳定,而低聚合度的Ala变化显著;Alb电中和能力强,对溶解性有机物去除效果好,其絮体成长速度慢但絮体强度高;Alc具有较强的吸附架桥能力,能促进浊度的去除;预制Alc的吸附架桥能力强于水解生成的Alc,但其絮体恢复性能差。

Several polyaluminum chloride（ PAC） coagulants were prepared with different OH / Al ratios（ B values） and characterized by ferron assay. Coagulating humic acid-kaolin synthetic water was subjected to a jar test,and numerous parameters,including the zeta potential,UV254 absorbance intensity,and the flocs recovery factor and strength factor,were monitored to comprehensively evaluate the coagulation mechanism for different aluminum species and the floc characteristics. The results reveal a large change in the distribution of the aluminum species after adding the coagulant; this effect was greatest for lower OH / Al values. The content of Ala（ OH/Al = 0. 5） ranged from 69. 57% to 4%,while that of Alcranged from 9. 36% to 50%. The oligomers and polymers of the prefabricated aluminum formed in the coagulation process were relatively stable. Whereas the low degree of polymerization of Alachanged significantly,Albhas a low floc growth rate,strong charge neutralization ability,and high efficacy for the removal of DOMs but a high flocs strength. Meanwhile,Alchas strong adsorption and bridging capabilities,which can promote turbidity reduction. The adsorption bridging ability of precast Alcis stronger than the hydrolysis of Alc,but its floc recovery is low.