Effects of bio-sand filter on improving the bio-stability and health security of drinking water

Bio-stability and health security of drinking water have become basic requirements to protect human health. The conventional water purification process, which is composed of coagulation, sedimentation, filtration and disinfection, can not solve the problems of organic matters in the micro-polluted source water effectively. So the by-products generated in the chlorination disinfection increased the carcinogenic risks of drinking water. The higher concentrations of Fe, Mn and trace heavy metals in the water are also harmful to health. In this study, bio-sand filter was adopted to treat the micro-polluted source river water. UV254 was used as a controlling parameter to measure the organic matters, BDOC and TP were used as evaluation parameters to measure the bio-stability of water quality. Combined with the removal of Fe, Mn and trace heavy metals in the source water, the effects of bio-sand filter on improving the health security and bio-stability of drinking water were investigated. The results demonstrate that bio-sand filter has good removal of UV 254 , and the average removal is 37.13%. The average removal of Fe, Mn and trace lead and chromium are 74.75%, 76.55%, 74.07% and 68.82%, respectively. The bio-sand filter has good removal of BDOC and TP. The average removal of BDOC is 61.78%. The removal of TP ranges from 58.76% to 78.53%, and the average removal is 68.62%. Applying the bio-filtration process in the water purification process can remove the biodegradable natural organic matters and control the production of disinfection byproducts, as well as the re-growth of micro-organisms in the water distribution system. The bio-sand filter process can remove Fe, Mn and trace heavy metals from the micro-polluted source water effectively. The bio-sand filter has great significance to improve the bio-stability of water quality, to limit the re-growth of microorganisms in the water distribution system and to protect human health.