Study on Haloalkaliphilic Sulfur-Oxidizing Bacterium for Thiosulfate Removal in Treatment of Sulfidic Spent Caustic

CATEGORY: SPENT CAUSTIC
Study on Haloalkaliphilic Sulfur-Oxidizing Bacterium for Thiosulfate Removal in Treatment of Sulfidic Spent Caustic

Type	Journal Article
Author	Somaye Makzum
Author	Mohammad Ali Amoozegar
URL	Free Full Text Source:  http://www.scipress.com/ILNS.57.49
Volume	57
Pages	49-57
Publication	International Letters of Natural Sciences
Date	8/2016
Abstract	Due to the disadvantages of physiochemical methods for sulfidic spent caustic treatment, attentions are drawn to the environmental-friendly biotreatments including sulfur-oxidizing haloalkaliphiles. Thioalkalivibrio versutus DSM 13738 was grown at alkaline (pH10) autotrophic medium with sodium carbonate/bicarbonate as the sole source of carbon and amended with sodium thiosulfate as the electron and energy source. The effect of various parameters including temperature (25-40 °C), pH (8-11), NaCl concentration (0.5-5 % w/v) and sodium thiosulfate concentrations (100-750 mM) was evaluated on bacterial growth and thiosulfate removal. This strain could eliminate sodium thiosulfate at very high concentrations up to 750 mM. The results showed that the highest specific growth rate was pH 9.5 and thiosulfate removal of Thioalkalivibrio versutus occurred at pH 10.5. The optimum salt concentration for thiosulfate removal was 2.5 % w/v and 5 % NaCl and specific growth rate elevated 2.5% w/v. It was also specified that this strain thrives occurred in 37 ºC and at 35 and 37 ºC higher removal of thiosulfate. Following chemical oxidation of sulfide to thiosulfate, application of Thioalkalivibrio versutus could be promising for spent caustic treatment. Since thiosulfate is utilized as an energy source, highest removal efficiency occurred at marginally different conditions compared to optimal growth.