Influence of Micro-bubble on Ozone-Decomposition of Excess Sludge

For the phosphorus recovery from the excess sludge in the sewage treatment process, the decomposition of excess sludge by using ozone micro-bubbles was focused, and the influence of ozone micro-bubble on the foam behavior and the decomposition performance was examined. A cocurrent upflow bubble column with micro-bubble generator was used and the excess activated sludge was decomposed under the various conditions. The foam behavior was observed and the decomposition performance was measured. The foam behavior was quite different with the bubble size. When ozone micro-bubbles were dispersed, the ozone decomposition was much enhanced. As a result, the decomposition time and required amount of ozone became much lower than those in the case of milli-bubbles.