Abstract
In this study, continuous experiments were conducted to examine whether application of copper water pipes could control the occurrence of endotoxin (ET) and the regrowth of viable microbes in feed water for healthcare facilities. Three annular reactors were equipped with test coupons made of polycarbonate (PC), stainless steel (SUS) and copper (Cu), and served for the experiments for 49 days. Biofilm samples were collected from the test coupons, then heterotrophic plate count (HPC) and ET activity were analyzed on a weekly basis. At the end of the experiment, 9 microbes were isolated from the biofilm samples and their ET producing capacities were evaluated. Strains of 6 isolates were identified using 16r RNA gene analysis. Growth rate of heterotrophic bacteria on the Cu coupons was much higher than other coupons due to decay of residual chlorine in the reactor accompanied with oxidation of the surface of the Cu coupons. On the other hand, ET activity on the Cu coupons was the least among all of the coupons. It was suggested that the Cu coupons could control specific microbes that have extremely high ET producing capacity, e.g., Pelomonas puraquae.
