Screening for fecal contamination via microbial water quality monitoring is a critical component of safe drinking water provision and public health protection. Achieving adequate levels of microbial water quality testing, however, is a challenge in resource-limited settings. One strategy for addressing this challenge is to improve the efficiency of monitoring programs. In African countries, quantitative microbial testing methods are commonly used to monitor chlorinated piped water systems. However, presence/absence (P/A) tests may provide an appropriate alternative for water supplies that generally show negative fecal contamination results. This study compares 1048 water quality test results for samples collected from five African urban water systems. The operators of the systems conducted parallel tests on the 1048 samples using their standard quantitative methods (e.g., most probable number or membrane filtration) and the Colitag™ method in P/A format. Combined data demonstrates agreement rates of 97.9% (1024/1046) for detecting total coliforms and 97.8% (1025/1048) for detecting E. coli. We conclude that the P/A test offers advantages as a simpler and similarly sensitive measure of potential fecal contamination for large, urban chlorinated water systems. P/A tests may also offer a cost-effective alternative to quantitative methods, as they are quicker to perform and require less laboratory equipment.
Color parameters were measured using a CM-2002 Minolta Spectrocolorimeter. Lightness varied from its lowest value of 77.68 to its highest value of 79.60 with coefficients of variation less than 1%. Lightness was statistically (p<0.05) the same for filtration and clarification; and for drying and deodorization. There was no significant difference in greenness from filtration through drying, although the highest greenness (a = -1.18) was obtained after deodorization. Yellowness was statistically equal at filtration (b = 31.34) and clarification (b = 31.19); at washing (b = 33.08) and drying (b = 33.02). Results showed that the spectrocolorimeter was consistent and the step of washing yielded the lightest cocoa butter.
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