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publications > open file report > OFR 2007-1374 > mitigation of sulfate using chemical treatment
6. Mitigation of Sulfate Using Chemical Treatment6.1 Barium sulfide treatment -This in an interesting approach to sulfate removal from water that relies on the insolubility of barium sulfate in water (Maree, 1991). It can be used in combination with limestone neutralization (see section 5.1). The sulfate-containing water for treatment is dosed with barium sulfide. Carbon dioxide is bubbled through the system to keep the pH acidic (close to pH 5). The barium reacts with the sulfate in the treatment water and barium sulfate is precipitated. The sulfide from the barium sulfide that was added converts to H2S by reaction with water under the acidic conditions, and is bubbled from the water to the atmosphere with an air stripper. The treatment water is sent to a neutralization tank or reservoir where lime is added, or run through a limestone neutralization system to adjust pH to near neutral. The treatment water may then be released to the system. The precipitated barium sulfate may be collected and disposed of, or may be regenerated to barium sulfide by heating in a kiln to 1200 °C using natural gas and petroleum coke.The process may reduce sulfate in treatment water to relatively low levels (e.g. about 5 mg/L). It is also possible to use barium oxide or barium carbonate in this process instead of barium sulfide. Heavy metals are often co-precipitated with the barium sulfate. The formation of insoluble barium sulfate is fairly rapid, and the removal (precipitation) of the barium sulfate from the treatment water can be monitored using a turbidometric approach. |
U.S. Department of the Interior, U.S. Geological Survey
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Last updated: 02 January, 2008 @ 09:02 AM(KP)