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Comment 2. The anion resin will be operated in the sulfate form. That <br /> is, sulfate ions will be exchanged for hexavalent chromium as described <br /> in the Description of Operation. For each hexavalent chromium particle <br /> removed, one sulfate ion will be released. The sulfate (SO4) ion has a <br /> higher molecular weight than hexavalent chromium (Cr) . Therefore, if <br /> the incoming concentration of hexavalent chromium is 10 mg/1, expressed <br /> as Cr, the effluent concentration of sulfate will be approximately <br /> 18 mg/1 expressed as SO4. <br /> The cation resin will be operated in the hydrogen form. Hydrogen ions <br /> will be exchanged on a one—to—one basis for the cations removed. Extra <br /> hydrogen ions will tend to reduce the pH, therefore the effluent pH will <br /> be neutralized using sodium hydroxide. <br /> Therefore, sodium and sulfate will be discharged in the treated effluent. <br /> However, the concentrations added as a result of treatment will be <br /> relatively small. We question the need for setting effluent limits for <br /> these constituents. <br /> Comment 3. The sampling locations are described in the revised Description <br /> of Operation submitted. The proposed Treatment Plant Startup Program is <br /> also submitted for your review and consideration. <br />