Filtering effects to bacteria and improvement of water quality by granite porphyry materials

The authors have investigated the filtering effects to bacteria and E. coli and the elution/adsorption for minerals, residual chlorine, COD, and organochlorine compounds by using granite prophyry, Bakuhanseki. The filtering effects of Bakuhanseki to bacteria were appeared, particularly the reduction rates of E. coli were 24.5 ± 8.32 and 84.4 ± 1.50% for Taihei river water samples and more than 50% for bath water samples, and the effects were accelerated by silver-coated Bakuhanseki materials. Residual chlorine and COD components in tap water reduced rapidly by one-pass flow through Bakuhanseki layer, and in the cyclic treatment system with the layer, the increases in concentrations of essential elements of Na, K, Fe and Ca were particularly shown, as well as the decreased concentrations of trihalomethanes and related compounds.