effect of vermifiltration on cod and color removal from textile factories’ waste water

aims: textile industries are among the manufactures which produce the highly polluted waste water. the purpose of this research was to evaluate the effect of vermifiltration on cod and color removal from textile waste water. materials & methods: this experimental research was performed march to august 2014 in one of the textile factories of kashan region, iran. the glass cubic kits with- without eisenia fetida were used to filter the waste water samples. data was analyzed using kruskal–wallis and two-way analysis of variance in spss 19 statistical software.   findings: the mean of cod concentration in the raw waste water samples was 1324.24±757.01mg/l which was decreased to 598.22±349.33 and 831.32±445.19mg/l after the experimental and control kits usage, respectively (p<0.001). the mean of color intensity in raw waste water samples was 51.2±30.6% which was decreased to 27.8±15.0 and 27.4±15.1% (p=0.635) in experimental and control kits, respectively. there was a significant negative correlation between cod removal and hydraulic loads (p<0.001 r=-0.804) and a significant negative correlation between color removal and hydraulic loads (p<0.001 r=-0.278) in both experimental and control kits. conclusion: vermifiltration is an effective method for cod removal from textile waste water, while have not considerable effect on color removal.