removal of arsenic and coliform bacteria by modified sand filter with slag and zeolite from drinking water

Background: among the various adverse pollutants in water, coliform bacteria and arsenic are very important. drinking of arsenic- contaminated water has become a serious threat to public health and has affected millions of people across the world. objectives: the aim of this study was to investigate the removal of arsenic and coliform bacteria from drinking water in small communities with the use of a conventional slow sand filter (ssf) and modified filter by slag (smf) and zeolite (zmf). methods: in this study, initial concentrations of arsenic were 0.073, 0.11, 0.171, 0.21, 0.24, and 0.33 mg/l and the initial number of coliform bacteria was 4*10^6 mpn/100 ml. arsenic and coliform bacteria samples were taken every 24 and 48 hours, respectively. concentration of arsenic was analyzed by inductively coupled plasma atomic emission spectroscopy (icp-aes) and the total and fecal coliforms were measured by multiple probable number (mpn) 9-tubes method. results: the results showed that the mean removal efficiency of arsenic (mean 0.189 mg/l) by ssf, smf, and zmf was 33.7%, 51.5%, and 66.2%, respectively. it was shown that the filter modified by zeolite had more efficiency in arsenic removal because of higher cation exchange capacity (cec) than any other media. the removal efficiencies of coliform bacteria by ssf, smf, and zmf were 1.97, 1.98, and 1.99 log, respectively. conclusions: this treatment method can be used as a simple, cheap, and convenient technique for arsenic and coliform bacteria removal from small communities’ drinking water resources.