|
At present, most countries use activated sludge to deal with waste water. Based on this treatment, the method can produce a large number of excess sludge to the environment, directly or indirectly cause the secondary pollution. In this paper, we use mechanical high-speed discs to break cell walls, so that we can make organic matter in cells pour into water to realize the purpose reducing excess sludge. we mainly research:the fluid analysis of high-speed discs; the mechanical characteristics of fluid between rotating disks, velocity, shearing stress, pressure changes; respectively, we analyze the cracking characteristics of cell walls by micelle-scale and bacteria scale in order to make sure how the fluid dynamics mechanism works. Base on theoretical analysis, we use experiments to research implementation of high-speed discs and watch the effect of destroying excess sludge. We mainly focus on cytoplasm out of the cells, the extent of broken cell wall; analyze particle size of broken sludge, scan the excess sludge cells before and after experiments with SEM.The experimental results show that the using mechanical methods of High speed discs to break excess sludge is useful, so that the dissolution of intracellular substances, leading to the value of SCOD, BOD, nucleic acids, proteins and other substances increasing. With the increasing in wheel speed, narrow plate spacing, the broken effect is more obvious. Reaction time of 35 minutes later, samples of the material and content do not significantly increase any longer, indicating that its effect does not change any longer.Analysis of the mechanism of mechanical wheel, I find that because of fluid viscosity, velocity gradient can produce shearing stress, it is the fundamental driving force for fragmentation, the abrasive wheel and features on discs play a supporting role.
|