Twelve different powdered activated carbons (PACs) were screened under laboratory conditions to determine their performance in the removal of chlorite ions (ClO₂⁻) and in the production of chloride ions (Cl⁻) and chlorate ions (ClO₃⁻) during that removal. All screenings were conducted in reagent water, at pH 7.0 ± 0.2 pH units, with a standard concentration of 20 mg/liter of powdered activated carbon (PAC) added in each case, and with the process and samples protected from light. One set of screening experiments was conducted with both ClO₂⁻ and chlorine added with the PAC, while the other set contained only ClO₂⁻, and PAC. The chlorine and ClO₂⁻ were added to concentration levels which might be expected in disinfection practice in water treatment plants.
Periodic samples were drawn as the mixtures were stirred over a 24 hour period. Each sample was analyzed for Cl⁻, ClO₂⁻, and ClO₃⁻ concentrations utilizing ion chromatography. All PACs were found to reduce ClO₂⁻ to Cl, and ClO₃⁻ was never detected when chlorine was absent. The data provided no consistent significant evidence of ClO₃⁻ formation even when chlorine was present. The rate of ClO₂⁻ removal was most rapid in the first two hours of contact, but slowed to rates below 6 percent per hour after 4 hours of contact. Rates of ClO₂⁻ removal varied with PAC type. The overall rate of ClO₂⁻ removal was also slower, with the total percentage of ClO₂⁻ removal less, when chlorine was present in the mixture. / Master of Science
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/43659 |
| Date | 11 July 2009 |
| Creators | Mitchell, Robert M. |
| Contributors | Environmental Engineering |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis, Text |
| Format | viii, 226 leaves, BTD, application/pdf, application/pdf |
| Rights | In Copyright, http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | OCLC# 28693567, LD5655.V855_1993.M583.pdf |
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