Removal of Hydrogen Sulfide from Groundwater Using Packed-Bed Anion Exchange Technology

he presence of hydrogen sulfide in potable water can result in taste, odor, and corrosion problems. Typical approaches for controlling hydrogen sulfide include oxidation and aeration (Sammons 1959, Sheppard and von Lossberg 1948, Lyn and Taylor 1991, and Dell’Orco et al. 1998), but the effectiveness of these treatment options depends on the hydrogen sulfide concentration and the pH. In the 1950s, anion exchange technology for removing hydrogen sulfide was proposed (Thompson and McGarvey, 1953), but limited information on the use of anion exchange for groundwater treatment has been reported. This article will assess the feasibility of using bed-packed anion exchange for removing hydrogen sulfide from groundwater. Hydrogen sulfide is not directly regulated under the Safe Drinking Water Act, but it is indirectly regulated through the secondary standards for taste and odor. In 2003, the Florida Department of Environmental Protection (FDEP) issued a rule under Chapter 62-555.315(5) concerning the control of total sulfide in new groundwater sources. The rule recommends treatment options based on the pH and the total sulfide concentration. The options include the use of chlorine, conventional aeration with and without pH adjustment in groundwater sources with hydrogen sulfide concentration between 0.3 – 0.6 mg/L, forced draft aeration including pH adjustment in hydrogen sulfide concentration in a range between 0.6 and 3 mg/L, and packed tower plus pH adjustment for sources with hydrogen sulfide concentrations over 3 mg/L. Oxidation converts hydrogen sulfide to either elemental sulfur or sulfate. Aeration results in a combination of stripping the volatile fraction of the hydrogen sulfide and oxidizing the hydrogen sulfide to elemental sulfur or sulfate. The volatile fraction is the nonionized form (H2S), and the concentration depends on the pH. In many cases, aeration systems promote the growth of sulfuroxidizing bacteria that can contribute turbidity to the finished water. An alternative approach for removal is to capitalize on the fact that a significant fraction of the hydrogen sulfide is ionized under pH conditions of natural waters, so anion exchange systems can be designed to remove it. To date, the major applications of anion exchange for drinking water are removing arsenic, nitrate, and organics (Korngold et al 2001, Ghurye et al. 1999, Kim and Benjamin 2004, Liang et al. 1999, and Bolto et al. 2002). Other applications include removing cadmium (Zhao et al. 2002), reactive dyes (Karcher et al. 2002), and hydrogen sulfide (Thompson and McGarvey, 1953). Ion exchange resins consist of a Removal of Hydrogen Sulfide from Groundwater Using Packed-Bed Anion Exchange Technology