Alkaliphilic Bacterial Sulfur Oxidation in Blast Furnace Slag Blowing Water

• Published in: Journal of Japan Society on Water Environment Vol. 38; no. 6; pp. 167 - 172
• Main Authors: YAO, Yasuko, ODASIMA, Kazuko, ISAWA, Tomoo, YABUTA, Kazuya
• Format: Journal Article
• Language: Japanese
• Published: Tokyo Japan Society on Water Environment 2015; Japan Science and Technology Agency
• Subjects: Alkaline blowing water; Bacteria; Blast furnace components; Blast furnace slags; Blowing; DNA; DNA sequences; DNA sequencing; High temperature; Hydrogen ions; Incubation period; Iron; Iron-making process; Ironmaking; Oxidation; pH; pH effects; Slag; Sodium; Sodium thiosulfate; Sulfates; Sulfur; Sulfur compounds; Sulfur oxidation; Sulphur; Thiosulfate; Thiosulfates; Wastewater treatment; Water shortages; Water supply; Water treatment
• ISSN: 0916-8958; 1881-3690
• DOI: 10.2965/jswe.38.167

Blowing water used for cooling blast furnace slag from the iron-making process is expected to be strongly alkaline because alkaline components of blast furnace slag are dissolved in it. However, actual blowing water in a water supply tank has a neutral pH. On the assumption that bacteria in blowing water cause pH to decrease, we conducted incubation experiments using blowing water controlled at a pH of 10 or higher. The pH of blowing water decreased at 60°C upon the addition of sodium thiosulfate. The concentration of sulfate also increased. DNA sequencing results revealed that the proportion of Thermi in this thiosulfate-stimulated blowing water increased to 83%. Thus sulfur-oxidizing bacteria that exist in high-temperature, high-pH blowing water oxidized thiosulfate into sulfate and hydrogen ion, so that the blowing water was neutralized. This bacterial reaction in a water supply tank is crucial for wastewater treatment of blowing water to decrease its pH and oxidize sulfur compounds.