BACTERIAL REMOVAL AND PROTOZOAN GRAZING IN BIOLOGICAL SAND FILTERS

Biological removal mechanism occurring in sand filters in purification processes of bacteria from wastewater. Eleven sand filters columns seeded with wastewater and bacteria are sampled for bacteria and protozoa enumeration. The experiments demonstrate that protozoan grazing plays an important role as a bacterial removal mechanism in sand filtration systems during wastewater treatment processes, with a significant correlation between numbers of protozoa in sand filter and removal efficiency of bacteria.