Objectives To evaluate the bacteriostatic effect of water containers made of brass or red-copper on Escherichia Coli, and to provide scientific reference for the optimal method of storing water in containers.
Methods Drinking water samples inoculated with Escherichia Coli at different densities were stored in copper containers or plastic container for a week.The bacteriostatic effect of copper containers on Escherichia Coli in water samples were evaluated at 4, 8, 24, 48, 72, 96 and 168 h of storage.The Most Probable Number (MPN) value of Escherichia Coli was analyzed, and the dissolution of copper and zinc in brass and red-copper container was also detected.
Results No inhibition effect was observed for plastic container on Escherichia Coli, however, the inhibition effects were observed for both brass and red-copper containers.In the low inoculation group, the inhibition rates at 4, 8 and 24 h for red-copper container were 62.5%, 83.3% and 100% respectively, while those for brass container were 29.2%, 37.5% and 100% respectively.In the high inoculation group, the inhibition rates at 4, 8 and 24 h for red-copper container were 94.8%, 99.5% and 100% respectively, whereas those for brass container were 0%, 0% and 98.6% respectively.The dissolution of zinc (Zn) in brass container was significantly higher, with a peak concentration of 1.46 mg/L, but no copper (Cu) was dissolved in water.However, the dissolution of Cu in red-copper container was significantly higher, with a concentration of 0.84mg/L, whereas no dissolution of Zn was found.
Conclusions There was a bacteriostatic effect of both brass and red-copper water containers on Escherichia Coli, and the bacteriostatic effect of red-copper container was better than brass container.The type and concentration of metals dissolved from different copper containers might be the major factors for bacteriostatic effects.
DownLoad: