Abstract

A study aimed at designing, constructing and evaluating a cost-effective biosand filter was undertaken. The biosand filter was modified with the addition of zeolites (clinoptilolite). The zeolites formed the largest part of the filter media which comprised of four layers. The complete filter had six zones which played a role during the filtration process. Filtration was done for 3 h to mimic water filtration in private homes. The filtered water was collected in a vessel for 1 h after which the samples were taken for analysis. Results indicated removal of up to 80 calcium, 89 magnesium, 99 iron, 56 arsenic, 54 fluorides, 96 turbidity, 37 nitrates and 41% total organic carbon. Higher turbidity (r = 0.024) and chlorophyll a (r = -0.566) concentrations resulted in a decrease in the flow rate of the filter which was between 1.74 â„“/h and 19.20 â„“/h. Higher chlorophyll a concentrations resulted in higher turbidity (r = 0.609). The filter was cost-effective (<US$20.00), and easy to construct, operate and maintain.

Key words: Biosand filter, zeolites, total organic carbon, chlorophyll a.