Flocculation - Air Flotation Treatment of Wastewater from Paper-making Reconstituted Tobacco Sheet

Abstract

In order to study the remove rate of organic pollutants in wastewater from paper-making reconstituted tobacco, and flocculation-flotation method was used to pretreat wastewater was discussed in this paper. The cationic polyacrylamide (CPAM) was used as coagulant, polymeric sulfate (PFS) and polyaluminium chloride (PAC) were used as flocculant. The effects of wastewater temperature, pH value, the type and dosage of flocculant and coagulant, the pressure and inflow of the air flotation on the flocculation and sedimentation of wastewater were analyzed. Research indicates: PFS was used with CPAM with relative molecular weight of 11 million and 40% ion degree, which had the best flocculation result. At the temperature of 32 °C, the pH of 6.5, the PFS dosage of 400mg/L, the CPAM dosage of 5mg/L, the air flotation inflow of 150m3/h, the air flotation pressure of 0.35Mpa, the CODcr, SS and chroma removal rate are 65.2%, 87.43% and 72.53% respectively, which achieved the optimum effect. Under the optimum conditions, the operating cost of wastewater pretreatment by the method of flocculation – flotation was 2.72 yuan per ton.