Analysis of the mechanism of sludge ozonation by a combination of biological and chemical approaches.
Using the practical sludge obtained from municipal sewage treatment plants, the mechanism of the sludge ozonation process was systematically investigated by a combination of biological and chemical approaches, including analysis of the changes in biological response by CFU and PCR-DGGE, bio-macromolecular activity and radical scavenging activity. The results indicated that after the sludge was exposed to ozone at less than 0.02 g O(3)/g TSS, the DGGE fingerprint remained constant and there was still some enzyme activity, indicating that the sludge solubilization was the main process. At greater than 0.02 g O(3)/g TSS, the bacteria began to be broken down and ozone was used to oxidize the bio-macromolecules such as proteins and DNA released from the sludge. Bacteria belonging to 'G-Bacteria' were able to conserve their DNA in the presence of less than 0.08 g O(3)/g TSS. At levels higher than 0.10 g O(3)/g TSS, the disintegration of the sludge matrix became slow and the microbes lost most of their activity, and ozone was used to transform the bio-macromolecules into small molecules. However, at levels higher than 0.14 g O(3)/g TSS, the ozone failed to oxidize the sludge efficiently, because several radical scavengers such as lactic acid and SO(4)(2-) were released from the microbial cells in the sludge.
Yan
Sang-Tian
ST
Department of Chemical Engineering, Tsinghua University, Beijing 100084, China.
Chu
Li-Bing
LB
Xing
Xin-Hui
XH
Yu
An-Feng
AF
Sun
Xu-Lin
XL
Jurcik
Benjamin
B
D001419:Bacteria / Q000166:cytology; D002681:China; D015169:Colony Count, Microbial; D004798:Enzymes / Q000378:metabolism; D010126:Ozone / Q000378:metabolism*; D012722:Sewage; D012995:Solubility; D012996:Solutions; D013481:Superoxides / Q000378:metabolism; D018508:Water Purification / Q000379:methods*
D004798:Enzymes; D012722:Sewage; D012996:Solutions; D013481:Superoxides; D010126:Ozone