ABSTRACT
Most conventional water treatment plants are not sufficiently equipped to treat both intracellular and extracellular Microcystins in drinking water. However, the effectiveness of sodium hypochlorite in removing Microcystin in containers at the point-of-use is not yet known. This study aimed to assess point-of-use water container treatment using bleach or sodium hypochlorite (NaOCl) and to assess the health problems associated with microcystins. Thirty-nine percent (29 of 74) of the total selected households were randomly selected to receive and treat their stored container water with sodium hypochlorite. The level of microcystin in the container water was measured after 30 min of contact with sodium hypochlorite. Microcystin concentrations in both the blooming and decaying seasons were higher (mean 1.10, 95% CI 0.46-1.67 µg/L and mean 1.14, 95% CI 0.65-1.63 µg/L, respectively) than the acceptable limit of 1 µg/L in households that did not treat their water with NaOCl, whilst in those that did, there was a significant reduction in the microcystin concentration (mean 0.07, 95% CI 0.00-0.16 µg/L and mean 0.18, 95% CI 0.00-0.45 µg/L). In conclusion, sodium hypochlorite treatment decreased microcystin s to an acceptable level and reduced the related health problems.
Subject(s)
Decontamination , Disinfectants , Disinfection , Equipment Contamination/prevention & control , Harmful Algal Bloom , Microcystins/analysis , Sodium Hypochlorite , Water Microbiology , Water Purification/instrumentation , Water Supply , Humans , Microcystins/toxicity , Risk Assessment , Water QualityABSTRACT
The study investigated the effects of cyanobacteria toxins such as microcystins in water sources and water stored in containers during its blooming and decaying seasons. Samples from water sources and containers near the Hartbeespoort Dam in South Africa were analysed using a microcystin ELIZA test kit. Microcystins were present in water sources used by the community, with an average of 4.3 µg/L in communal tap water and 4.8 µg/L in the water stored in tanks. The concentration of microcystins was lower in groundwater in the decaying season (0.38 µg/L) than in the blooming season (1.4 µg/L). Although microcystins were present in the storage containers, the average levels in all water samples were below the acceptable limit of 1 µg/L. The present study confirmed the presence of microcystins in the water storage containers. Therefore, it is suggested that water used for drinking from community water sources should be treated before storage to eliminate microcystins.