Effect of Calcium Carbonate and Calcium Sulfate on E.coli Survival in Fine Sand Mixtures

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Abstract

Water and soil pollution by human pathogenic bacteria draw attention of many researchers. Duration of bacterial survival for reach to the soil and water resources is very important. Current study focused on the effects of CaCO3 and CaSO4 compounds on Escherichia coli survival. Using CaCO3, CaSO4 compounds and fine sand particles (<0.01mm), two types of mixtures with 20 %, 40 %, 60 % and 80 % levels were prepared under sterilized condition. Field capacity of mixtures was calculated using plate pressure device. One milliliter of diluted manure extract in 1:20 proportion added to the mixtures and they were incubated in 28 ?C. A total of 0.1 ml of extracts were added to the plates containing Eosin Methylene Blue (EMB) medium. After 2.5, 5, 10 and 15 hours bacterial CFU were counted using colony counter. DATA were analyzed using SAS software. Results indicated that chemical properties of manure, mixture of sand-calcium carbonate and sand-calcium sulfate had no effect on Escherichia coli survival. Effects of time and kind of compound on bacterial growth showed significant differences (P<0.0001). Treatment means comparison showed that CaCO3 concentration higher than 20% decrease severely bacterial growth but no effect on bacterial growth were observed for various levels of CaSO4. Mean of colony forming unit (CFU) of bacteria on mixture of sand-calcium sulfate were higher than mixture of sand-calcium carbonate in all levels of concentration. Also effect of time on bacterial growth in tested mixture was significant (P<0.0001). Bacterial growth in the presence of calcium carbonate and calcium sulfate in the levels higher than 20% were decreased and increased respectively. As a result if CaCO3 compound is used to the waste discharge system, E.coli cells would be filtered, on the other hand this compound is plenty in geological area of Iran, which can decrease filtration costs.

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Journal of Environmental Studies
Volume 38, Issue 2 - Serial Number 2
September 2012
Pages 117-126

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