Sulfur Cycle - (brief)

Hydrogen sulfide is formed through the enzyme activity of the anaerobic bacteria, Desulfovibrio desulfuricans and other similar species.

Alken-Murray addresses the problems created by hydrogen sulfide in aerobic systems or lagoons open to the air, with Alken Nu-Bind, Alken Enz-Odor 6, Alken Enz-Odor 8, Alken Enz-Odor 9, Alken Enz-Odor 14 and Alken 896.

For anaerobic digesters, we utilize a combination of Alken Clear-Flo® 7020 and Alken Enz-Odor 10 to degrade greases and fats into fatty acids, utilized by Methanogens and also to protect these fragile organisms from hydrogen sulfide. Alken Enz-Odor 5 can be used in either aerobic or anaerobic systems and will also control hydrogen sulfide in manure systems of chickens, poultry, swine, pigs and hogs.

Under the anaerobic conditions of the waste pits, it is sometimes necessary to add 10 to 100 ppm of sodium nitrate (safe below 50,000 ppm), although adding Alken Enz-Odor 10 is often an easier solution. Sodium (and/or calcium) nitrate offers an alternate electron acceptor so that hydrogen sulfide will degrade to sulfate instead of forming corrosive sulfuric acid, which could shock the system by suddenly decreasing the pH. Bacteria utilize hydrogen acceptors in the following order: 1) O2, 2) NO3 and 3) SO4. In theory, under anaerobic conditions, no sulfide can be generated until all of the nitrate has been reduced to nitrogen gas.

Fresh swine feces contain a mean value of 1.8 lbs. of sulfur (range 0.24 to 2.9) per ton, with 0.01 lbs. of sulfur per day per head of swine. A liquid slurry with 5% moisture typically has a mean value of 4.7 lbs. per 1,000 gallons (range 0.42 to 18 lbs. per 1000 gal.). This corresponds to 0.011 lbs. of sulfur per head, per day. Without adequate treatment, at least 25% of this will volatilize as hydrogen sulfide gas. For more in depth information on this subject, see our treatise on hydrogen sulfide.