Effect of Charcoal-Sand Filtration, Chemical Disinfection and Solar Heating on Bacteriological and Physiochemical Quality of Surface Water

In our effort to contribute to availability of safe drinking water, we designed a laboratory scale and prototype charcoal- sand filtration
(CSF) reactor (31.5 by 35.0 cm) for the treatment of surface water for rural dwellers. The qualities of charcoal-sand filtered solar treated water samples were monitored using standard plate count technique for total bacteria and total coliforms. Bacterial isolates from CSF water were evaluated for antibiotic resistance pattern. Sensory evaluation of the treated surface water was done using a 20- man panel and the result was statistically analyzed. Charcoal-sand filtration of the raw water produced reduction of total viable bacteria counts (TVB) of 91.3% and 77.0% of TCC. The CSF in combination with solar disinfection (SODIS) resulted to reduction by 92.7 % and 97.4% of TVB and TCC respectively. The CSF-chlorinated water and CSF-citrated water were free of bacteria. Thirty-Six Gram-negative bacterial isolates were recovered from raw water samples. They comprised Escherichia coli (36.1%), Enterobacter aerogenes (24.1%), Klebsiella pneumoniea (10.8%), Salmonella Typhi (8.4%), Shigella dysenteriae(8.4%) and Pseudomonas aeruginosa (12.0%). No significant difference was noticed between the overall acceptability and organoleptic properties in terms of taste, odour as well as clarity of CSF-SODIS water and CSF-chlorinated or CSF-citrated water (Probability=95%). The physic-chemical quality of CSF-SODIS water met the standard limit for drinking water. Hence, CFS-SODIS may be recommended for surface water treatment in rural communities to prevent outbreak of waterborne diseases