藻类絮凝体形态学特征及其与气浮的关系研究

采用聚合氯化铝(PAC)作为混凝药剂,利用混凝-气浮技术去除水中铜绿微囊藻(MA),用图像法对絮凝体的分形维数进行测定,分析不同混凝条件下的气浮除藻效果以及PAC-MA絮凝体的形态学特征,并探讨两者的关系.结果表明,在快速混合搅拌强度和时间分别为500 s-1和1 min,回流比为10%条件下,PAC最佳投药量范围为5.6-9.8 mg/L Al2O3,最佳点为8.4 mg/LAl2O3;最佳的絮凝反应搅拌强度范围为50～80 s-1,最佳点为50 8-1;最佳的絮凝时间范围为5～8 min;投药量、絮凝反应搅拌强度及时间对PAC-MA絮凝体形态有着显著影响,在最佳混凝条件下,絮凝体的二维分形维数D2较小,在1.168 8～1.235 7之:间,相对应的絮凝体的平均粒径较大,在300～500 μm之间;在适当的混凝条件下,结构疏松,枝权较多,尺寸较大的PAC-MA絮凝体与气泡粘附效果好,容易气浮去除.

Morphological Characteristics of Algae Floc and Its Relation with Flotation

Microcysits aeruginosa (MA) was removed by polyaluminium chloride (PAC) in the coagulation-flotation process. The test studied removing effect and morphological characteristics of PAC-MA flocs in the different coagulation conditions and discussed the correlation of them. Fractal dimension was measured by image analysis. The results indicate that the best range in dosage, stirring strength and time of flocculation reaction are respectively 5.6 - 9.8 mg/L Al2O3, 50 - 80 s(-1) and 5 - 8 min in the condition of mixing stirring strength of 500 s(-1), mixing time of 1 min, circulate ratio of 10%. The dosage, stirring strength and time of flocculation reaction influenced the form of flocs remarkably. Moreover the range of fractal dimension D2 is between 1.1688 and 1.2357, and average diameters vary between 300 microm and 500 microm with the best flocculation condition. The flocs with the looser structure, the bigger diameter variation and more branches can adhere to bubbles more easily.