After an annual swimming rally in the Nahoon river, concerns were raised after several swimmers fell ill, complaining of possible symptoms of mild E.coli infection. Research was hence conducted to determine the following:
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The Nahoon River is safe for recreational activity in terms of faecal-coliforms and E.coli
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Whether the amount of rainfall affects these levels.
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If faecal pollution is present, to determine the possible point sources of the pollution
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To devise a method that needs no assistance from a laboratory, and could be done in a home environment at low cost.
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Procedures
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Colilert-18, (the reagent) contains nutrients which react to faecal-coliforms and E.coli in the sample. It causes samples to change colour when contamination is present. A dilution method (used by the Kowie Catchment Campaign) was used to test the severity of the contamination. The dilution levels were as follows: 1, 1/10, 1/100 and 1/1000. A control test was also performed. One Colilert capsule was divided among the five samples, which were incubated in a household stove at 37ºC for 18 hours. A sample was collected every four days and after heavy rainfall.
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The results were rated on a severity scale of 0-4, where a two was considered unsafe for recreational activity. If the undiluted sample remained clear, it was ra ted 0, if all the samples changed colour, it was rated as a four. The same rating system was used when fluorescing samples to test for E.coli. The daily rainfall level was compared to the levels of faecal-coliforms and E.coli.
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Conclusion
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As it has high levels of faecal coliforms and E.coli, the Nahoon River is not safe for recreational activity on a daily basis.
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Heavy rainfall causes the levels of E.coli and faecal coliforms to rise.
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The major source of the contamination is a stream entering the river from a newly developed settlement, and not a leaking sewer.
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This experiment has developed cost-effective home environment testing method which could be used in researching other rivers, marine environments, recreational waters and even drinking water by community researc
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