comparison of conventional slow sand and modified filters with recycled crushed glass media in removal of turbidity and total and fecal coliforms from water resources

abstract background: the aim of this study was to compare the efficiency of conventional slow sand filter with modified filter bed with crushed recycled glass in removing of turbidity and total and fecal coliforms from water resources.   methods: in this study efficiency of conventional slow sand filter and modified filter bed with crushed recycled glass during 4 months was compared and their performance in removal of turbidity and total and fecal coliforms in synthetic water (influent turbidity and total and fecal coliform bacteria) with two separate filters which were operated in parallel and continuous flow was investigated. findings: the turbidity removal by conventional slow sand filters and modified filter bed with crushed recycled glass were % 97.28 and %96.93, respectively and the average of turbidity effluent were 0.49 ±0.19 and 0.55±0.36 ntu, respectively. the total and fecal coliform removal by conventional slow sand filter were 2.89 and 2.29 log, respectively and for modified filter bed with crushed recycled glass were 2.62 and 2.46 log, respectively. both filters have slightly effect on other measured physicochemical parameters and their values in water below who and iran standards. conclusion: the efficiency of modified filter bed with crushed recycled glass in removal of turbidity and total and fecal coliforms is approximately similar to a conventional slow sand filter. the crushed glass medium in comparison with conventional sand filter generate smaller head loss and smaller clogging, which is cost effective and environmental friendly and  shows significant promise as an alternative to silica sand in slow sand filtration. key words: water treatment- slow sand filter- crushed recycled glass medium- physicochemical parameters- microbial parameters