絮凝-DAF(dissolved air floatation)工艺的化学因素与颗粒特征研究

Study on the chemical factors and particle characteristics of the flocculation-DAF(dissolved air floatation) process

研究了絮凝 DAF工艺的化学因素和颗粒特征 .PAC类絮凝剂的碱化度B值越高 ,其荷电量和立体结构越显著 ,絮凝 DAF工艺的除浊效果越好 ;但除了絮凝剂的电中和能力外 ,其形成絮体的结构特征也对絮凝 DAF工艺有影响 .随着投药量、絮凝搅拌强度和时间的增加 ,絮体都分别会趋于某一极值尺寸而后逐渐变小 ,且较大粒度的密实絮体才是与微气泡作用效果最好的絮体 .此外 ,增加絮凝搅拌强度和延长时间都可能有利于水中颗粒的去除 ,且DAF出水中粒径越大的颗粒含量越少 ,其中大于 1 5μm的颗粒极少 ,但 2—

For PAC flocculants of higher basicity, the more surface charges and stereo structure of their components lead to better turbidity removal of flocculation DAF process. Besides this, the characteristics of the flocculated floc had some effect on the turbidity removal. The experiment results showed that flocs could aggregate to the extreme size, and then fracture with the increase of the dosage, flocculation mixing intensity and retention time. During DAF pilot runs, too small or too large flocs were unfavorable, medium and compact flocs could provide more opportunities of collision and more adhesion sites for the micro bubbles. Stronger and longer flocculation mixing could be beneficial to particle removal. The bigger particle, the less was in floated water. There were almost no particles more than 15?μm contained in floated water, but more particles of 2—4?μm than in reservoir raw water.