In-vitro inactivation of Escherichia coli of surface water using metals

Abstract

Technology for providing clean drinking water to remote areas of low-resource nations remains a significant challenge for human life The study aimed to develop a simple technology for rural households that might be adopted to utilize the bactericidal properties of metals. Three thick metal sheets made of copper, zinc, and brass (an alloy of copper and zinc) were used in this study work. These metallic sheets were placed in three plastic (polythene) containers with base areas 11cm x 7cm each so that the metallic sheets covered the entire base areas of the respective containers. Fifty ml, one hundred ml, and four hundred ml of contaminated water from a public pond were added to each container, covered with lids, and shaken/left undisturbed at room temperature. The microbial analysis of Total Aerobic Bacteria (TAB), Total Coliform Bacteria (TCC), and E. coli was done every 24 hours up to twenty-eight days of storage at room temperature. E. coli is considered an indicator of diarrhoeal pathogens. The initial bacterial counts were TAB: 4.22 log CFU/ml, TCC: 3.15 log CFU/ml, and E.coli: 3.13 log CFU/ml, respectively. TAB count did not reduce significantly for any of the metals used in this study. Total coliform counts decreased to almost half the original for all three metals in the first 24 hours but remained almost the same afterward. However, E.coli was inactivated entirely after treatment with copper within 24h and remained constant afterward. On the other hand, brass and zinc reduced E. coli by almost half in the first 24 hours but remained almost constant throughout the rest of the measured period. The findings mentioned above, a simple copper sheet might help inactivate diarrheal bacteria and provide safe drinking water within 24 hours. As a result, this may lead to the development of an easy technique to provide clean drinking water in remote areas of low-resource nations like Bangladesh. It is crucial to determine whether the level of copper in the water is within the safe range, as regular usage of higher doses might result in copper poisoning. A future study will attempt to optimize the relationship between the water volume to the copper sheet’s exposed surface area and the treatment time. Bangladesh J Microbiol, Volume 39, Number 2, December 2022, pp 54-59