| abstract |
The present relates to a method of using pure oxygen in microbial fermentation processes and wastewater treatment processes, in which the pure oxygen is produced by a pressure swing adsorption (PSA) process from a gas mixture of air and unused oxygen-containing recycled off-gas from microbial processes which uses oxygen-containing gas in a liquid or gas state. According to the present invention, when pure oxygen with a purity of more than 90% is used in microbial processes, microbial productivity can be about 5 times as increased as it is that in the conventional method using air with an oxygen content of 21%, and the volume of an active sludge tank in wastewater treatment processes can be reduced to at most 1/5 of the volume as compared to the conventional method. Also, the off-gas from such pure oxygen processes has a high oxygen content of about 70-80%. Thus, when the off-gas is recycled with air for the supplement of oxygen consumption, the gas mixture with an oxygen content of about 40% is used as feed gas for the PSA process, and CO2 generated by microbial breathing is also removed. Thus, in the present invention, the volume of a PSA column and an air compressor for supplying the feed gas can be reduced to less than ½ of the volume as compared to that of the use of air. |