The Nature of Sulfide Compounds and Their Formation:
Desulfovibrio Desulfovibrio desulfuricans, found in the digestive tract of both man and animals, is the most common bacteria which produce H2S under anaerobic conditions. These obligate anaerobes use sulfate as their oxygen source, ammonia as their sole source of nitrogen, and various forms of organic matter as a food supply including amino acids, carbohydrates, organic acids, etc., when in an oxygen limited environment. These reactions often take place in the slime layer on collection pipes and in the sludge of lagoons, etc.
These bacteria cannot compete well with the facultative anaerobic strains in Alken Clear-FloŽ formulas, which use nitrate as a hydrogen acceptor and reproduce more quickly than the sulfur-reducing pure anaerobes.
Sulfur-reducing bacteria also attack the protective sulfate coatings on metal and concrete, leaving them vulnerable to corrosion by sulfuric acid (H2SO4), resulting from oxidation of H2S. Other bacteria attack the asphaltic coatings which are normally resistant to chemical attack. Minimizing retention time will minimize the action of this bacteria. Oxidation Reduction Potential (ORP) between -50mV to -300mV favor sulfate reducing bacteria. -100mV to -200mV are favored by other anaerobes.
Reductions Which Create Hydrogen Sulfide: The serious odor and corrosion problems associated with the collection, handling and treatment of domestic wastewater are primarily the result of sulfate reduction to hydrogen sulfide under anaerobic conditions, as shown by the following reactions :
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In the biochemical oxidation of organic matter, bacteria remove hydrogen atoms from the organic molecule and, in the process, gain energy. Through a series of biochemical reactions, the hydrogen atoms are transferred to a hydrogen acceptor. The hydrogen acceptor may be an inorganic or organic substance. Under aerobic conditions, free oxygen is the final acceptor for hydrogen, the oxygen being reduced to water. In the absence of free oxygen, combined oxygen may be used as a final acceptor of hydrogen.
Other Reductions Which Lead to Odor
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Other Reductions which do NOT produce significant odor:
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