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SULPHIDE PRODUCTION FROM SULPHATE‐ENRICHED SEWAGE SLUDGES
Author(s) -
BUTLIN K. R.,
SELWYN SYLVIA C.,
WAKERLEY D. S.
Publication year - 1956
Publication title -
journal of applied bacteriology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.889
H-Index - 156
eISSN - 1365-2672
pISSN - 0021-8847
DOI - 10.1111/j.1365-2672.1956.tb00036.x
Subject(s) - fermentation , chemistry , methane , raw material , sewage sludge , sewage , food science , nuclear chemistry , waste management , organic chemistry , engineering
SUMMARY: Sterilized raw sewage sludge enriched with sulphate and inoculated with pure strains of Desulphovibrio desulphuricans produced negligible sulphide. Unsterilized sludge supplemented with 7% (w/v) CaSO 4 .2H 2 O and inoculated with crude cultures of sulphate‐reducing bacteria obtained from sewage yielded 1·0% S 2‐ (wt S 2‐ produced as H 2 S/vol. of raw sludge) in 6 months at 30°. By repeated subculture more active cultures developed which produced 1% S 2‐ in 7 days and 1·2–1·9% in 28 days. Digested sludge yielded only 0·1% S 2‐ . In semicontinuous fermentations at 30°, raw sludge without added sulphate produced 20 times its own volume of gas containing 70% CH 4 and 30% CO 2 . When 5% CaSO 4 .2H 2 O and an active crude culture of sulphate reducers were added, gas production decreased steadily to zero. There were no differences in pH, temperature and redox potential in sludges producing methane or sulphide. The chief cause of inhibition appeared to be the action of sulphide: 0·02% soluble sulphide (S 2‐ ) totally inhibited methane formation; 0·01% S 2‐ initially decreased gas production by one‐quarter but there was a slow recovery to normal, suggesting acclimatization of the methane‐producing organisms to sulphide. Linked fermentations, in which gas from a methane fermentation swept H 2 S from a sulphide fermentation, gave a final gas mixture of about 60% CH 4 , 30% CO 2 and 5–10% H 2 S. The yield of sulphide depended on the rate of sweeping.