Evaluation of a concrete cascade solar still

Abstract

The quality of the distilled water produced by the Concrete Cascade Solar Still wasevaluated by the comparison with the conventional electrically powered still used for the samepurpose and the quality of the tap water intake prior to these investigations. The samples weredrawn from the following areas: the cascade solar still (over a continuous five days period) ; theelectrically powered still; and a five day storage period (in the dark) of the previouslymentioned areas. The Water Quality Indices (WQI) were 4.50, 3.76 and 29.35 for the watersamples from the cascade solar still, the electrically powered still and tap water respectively. Theheavy metals and sodium and calcium profiles also showed that the tap water had higherconcentrations of these metals. However, the microbiological assays showed that the cascadesolar still had the highest colonies forming units (1400 CFU/ml) , with respect to the electricallypowered still (22 CFU/ml) and tap water (12 CFU/ml) . The C.V. for the selected parameterswere: 0.875, 0.214, 2.060, 1.443, 2.109, 0.218, 1.888, 0.436, 1.082, 1.081 and 0.939 for theconcentrations of iron, lead, calcium, zinc and sodium, and the values of pH, conductivity,turbidity, total suspended solids, chloride ions and microbiological assays respectively.