Hydrogen sulfide gas degradation by microorganisms isolated from raw sludge

Pseudomonas aeruginosa and Stenotrophomonas maltophilia were both isolated from canal sludge of Metro Manila using thiosulfate medium. The medium used in maintaining and performing the H2S gas uptake experiment was thiosulfate medium with 1g yeast extract. The cell were at its late logarithmic and early stationary phases of growth when gas was injected to the culture. Results showed that Steno.maltophilia exhibited lower capability in degrading H2S gas than Pseu. aeruginosa. Pseu. aeruginosa had totally degraded the gas on the first twenty minutes whereas for Steno. maltophilia, there is a reduction of 73.92 percent. Both microorganisms exhibited sensitivity to low pH. The experiment was conducted under batch condition. Gas volumes of 1,875, 1,259, 937.5 and 625 mL were injected to the Pseu. aeruginosa culture at flow rate of 12.5mL/s. The percentage reduction of H2S gas on the first 120min increased, from 34.61 percent to 73.07 percent, as the gas volume injected is decreased, from 1,250mL to 625ML, respectively, regardless of H2S gas concentration. No change in the number of cells was observed when gas volume injected was less than 1,000mL