Synergistic Effects of Combined Ozone and Dissolved Air Flotation for Treatment of Secondary Effluent from a Pulp and Paper Mill

摘要

Dissolved air flotation (DAF) plays an important role in drinking water treatment and wastewater tertiary treatment. During DAF treatment, compressed air is introduced into a recycle stream and gets dissolved and generates 10-100 u.m sizes of bubbles when released through a dispersion header in a DAF tank. Coagulated particles attach the bubbles and float to the top of the water column and are either mechanically or hydraulically removed. DAF with proper coagulation chemicals has been proven to be superior for the reduction of turbidity, colour, Cryptospohdium and Giardia, algae, iron and manganese, low density suspended solids, phosphorus, and chemical oxygen demand (COD) or total organic carbon removal (TOC).