RESUMO
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.
Assuntos
Compostos de Alumínio/química , Cloretos/química , Microcystis/crescimento & desenvolvimento , Purificação da Água/métodos , Cloreto de Alumínio , Compostos de Alumínio/farmacologia , Cloretos/farmacologia , Filtração , Floculação , Microcystis/efeitos dos fármacos , Microcystis/isolamento & purificação , Purificação da Água/instrumentaçãoRESUMO
High algae-laden water was treated respectively by single-recycle and step-recycle counter current flotation. The results indicate that step-recycle mode of dissolved air water can strengthen capturing of bubbles and flocs association suspension bed, and extend the collision time of smaller flee and bubble because of reducing the thickness of suspension bed and increasing that of transition bed. Given the condition that other parameters were same, the biggest hydraulic loading of single-recycle could reach 11 m/h, and that of step-recycle could reach 17 m/h which is increased by 50%. Efficiency of treatment was improved by a large margin. The recycle ratio of two releasers and position of the pensile releaser influenced removal effect remarkably. The distance between settled releaser and inlet of raw water is 180 cm, and the range of distance between pensile releaser and inlet of raw water is 60-90 cm. The flow of pensile releaser is 2-3 times as much as settled releaser.
