M2 Hideaki IKARASHI

Improvement of Anaerobic Digestibility of Sewage Sludge by Ozonation

Hideki HARADA, Akiyoshi OHASHI


Anaerobic digestion converts the organics present in thickened sewage sludge into biogas. But, drawback of the present technology lies in the slow hydrolysis reaction step. In this study, ozonation of the sludge applied to enhance hydrolysis and solubilization of the cell wall/cell membrane and release the cellular contents in the medium in order to increase digestibility of sludge. The main objective of this study is to investigate how extent microbial cells become to be solubilized.

Solubilization ratio took the related almost fixed value to the difference in inlet ozone gas concentration. This parameter increased in proportion to the reacted ozone dose. The tendency as solubilization ratio for the amount of methane gas production from the ozonation sludge by biodegradability test to be also the same was shown. The amount of methane gas production increases, so that the reacted ozone dose is so high that solubilization ratio is high. From the sludge observation using the microscope, it checked that digester sludge had solubilized and distributed by ozonation. I use Live/Dead Kit to distinguish solubilize or not of the microbial cells. It has checked that the number of live bacteria in sludge decreased, and a cell-lysis by ozonation from this experiment.