Conventional dissolved air flotation(DAF) has the problems of low efficiency for microbubble meshing and particle adhesion

and unstability of the adhesion between microbubbles and particles. In this work

a novel countercurrent-cocurrent dissolved air flotation(CCDAF) was developed

of which the contact room was consisted of collision and adhesion contact room

and each room was introduced dissolved air water. The results showed that the CCDAF significantly enhanced the adhesion efficiency of microbubbles-floc. The average removal efficiency of turbidity and algae were 96.4% and 96.50%

respectively. The diameter of particles for effluent was mainly ranged in 2-7 μm. Most of the removed substance was macromolecules and hydrophobic organic compounds. CODMn

UV254

DOC had achieved 37.6%

46.3% and 32.11%

respectively

indicating the significantly higher removal efficiency of CCDAF than the traditional DAF. The analysis of the removal mechanism between microbubbles and particles showed that the collision

adhesion and copolymerization in countercurrent room and collision

adhesion

wrapped

meshing and adsorption-bridging in cocurrent-contact room were probably the reasons to enhance the removal efficiency of this CCDAF.