Chlorine Demand and Microbiological Disinfection in Turbid Water.
Kaufmann, Anya C.
2014
- Abstract: Nearly 780 million people lack access to an improved water source and 1.5 million children under the age of five die each year due to diarrheal disease. Chlorinating water is one form of household water treatment that has been proven to be effective at disinfecting water; however, there is uncertainty in the ability of chlorine to effectively disinfect turbid waters. Turbid waters tend ... read moreto have a larger chlorine demand, and particulate matter in turbid waters can shield microorganisms from disinfection. A double dose (3.75 mg/L) of chlorine is recommended in turbid waters. This research investigated the chlorine demand and microbiological disinfection of turbid waters with 10, 100 and 300 NTU and 0, 2, 10, and 25 mg/L of additional total organic carbon (TOC) when a double dose of chlorine was applied. Experiments were run in a laboratory using reactors with 10 L of RODI water, Kaolin clay to add turbidity, a TOC standard solution to add TOC, E. coli inoculated broth to add E. coli, and Clorox® bleach to add chlorine. Temperature, pH, TOC, free chlorine residual, total chlorine residual, turbidity, and E. coli were measured over a 24 hour period following chlorination. Four major conclusions were drawn from this research: (1) a double dose of chlorine was not large enough to maintain free chlorine residual levels as recommended by the CDC SWS program over a 24 hour period, (2) waters with higher TOC concentrations have a higher chlorine demand, (3) a double dose of chlorine effectively disinfected water of 10, 100, and 300 NTU with average log reductions between 6.4 and 8.2, and (4) a double dose of chlorine did not result in all water samples meeting the WHO drinking water standard of <1 CFU/100mL when the initial concentration of E. coli was on the order of 10^8CFU/100mL.read less
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- zc77t203s
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- tufts:sd.0000069
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