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A continuous culture apparatus for the microbial utilization of hydrogen produced by electrolysis of water in closed‐cycle space systems
Author(s) -
Foster John F.,
Litchfield John H.
Publication year - 1964
Publication title -
biotechnology and bioengineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.136
H-Index - 189
eISSN - 1097-0290
pISSN - 0006-3592
DOI - 10.1002/bit.260060406
Subject(s) - carbon dioxide , electrolysis , electrolysis of water , hydrogen production , hydrogen , oxygen , chemical engineering , high pressure electrolysis , chemistry , volume (thermodynamics) , pulp and paper industry , materials science , electrolyte , electrode , organic chemistry , physics , quantum mechanics , engineering
Two sources of oxygen for man in closed‐cycle space system environment have been considered in previous studies: ( 1 ) photosynthesis using algae, and ( 2 ) electrolysis of water. The latter system appears to be the most promising from the standpoints of energy and weight requirements and ability to operate in a zero gravity field. The surplus hydrogen produced by the electrolysis of water may be utilized together with waste carbon dioxide, part of the oxygen, and waste urea by bacteria of the genus Hydrogenomonas to produce cellular protein which might be used as a source of food. A continuous culture system for the propagation of hydrogen‐fixing bacteria consists of a baffled borosilicate glass culture vessel provided with an impeller, a reservoir vessel for the culture medium, and an overflow vessel for collecting the bacterial cells removed from the culture vessel. Complete feedback control of all parameters affecting growth can be provided by hydrogen, oxygen, and carbon dioxide sensors, and a pH electrode in the culture medium. In addition, total pressure is monitored. Cell density is controlled in the optimum range by means of a photoelectric cell which dictates the amount of fresh medium to be added and the amount of cells to be removed. Operating data indicate that some of the key parameters are the ratio of hydrogen, oxygen, and carbon dioxide in solution. The harvested bacterial substance is high in protein, which contains all the essential amino acids.