The effect on various treatment methods on the disinfection of artificially contaminated water

ABSTRACT

Since waterborne diseases are still an important cause of morbidity and mortality in the Philippine setting, it is evident that the quality of water supplies cannot always be assured, and remedial measures are required to provide consumers with safe drinking water. Boiling is a proven household disinfection method, but doubt regarding its efficacy has led to a search for alternatives. This study was thus performed to compare the efficacy of various methods of water treatment, and to perform a cost analysis for each method Sterile water was seeded with E. Coli ATCC 25922 to a concentration of 10 exponent 5 cfu/ml. Equal amounts were then disinfected by(1) boiling for 10 minutes; (2) passage through an ultraviolet (UV) light water treatment device (UV Waterworks TM); (3) reverse osmosis (RO). Three replicates were done for each procedure, and for each replicate five aliquots were obtained for (1) immediate testing (2) testing after 24 hours in room temperature; (3) testing after 24 hours at a temperature of 2-8 degrees C; (4) testing after 48 hours in room temperature; and (5) testing after 48 hours at a temperature of 2-8 degrees C, Samples were analyzed using the spread-plate method on MacConkeys agar. For all samples taken, no growth was seen after 24 hours of incubation Taking into account the cost of consumables for each method, UV disinfection has the advantage of being 200 times less expensive than boiling, which in turn is less costly by 50 percent compared to RO. The increased cost of RO is due to large amount of water discarded during processing. An advantage offered by methods such as RO and UV disinfection is its time-saving aspect. However, households without access to UV or RO units should consider boiling a cost-effective option, so long as manpower and fuel resources are available. (Author)