RESUMO
In. the current study, the efficiency of starch and Plantago ovata extract as coagulant aids is compared in water turbidity removal. The coagulant is ferric chloride and the experiments are run in two ranges of pH 7 and 8. The achieved results of turbidity removal in different turbidity levels of 100, 50 and 20 NTU caused by different concentrations of starch and P.ovata as coagulant aids besides ferric chloride as the main coagulant are compared. According to the achieved results, the use of P.ovata or starch as the coagulant aid may play a key role in reducing the amount of FeCl[3] as the main coagulant and consequently decreasing the generated sludge. Furthermore, the remarkable turbidity removal efficiency gained when these coagulant aids are used in comparison with the case when no coagulant aid is introduced is also of interest. Generally, the both coagulant aids seem to be more efficient in pH value of 7 rather than 8. Although both coagulant aids used in this study manifested acceptable turbidity removal efficiencies, P.ovata showed higher capabilities of removal in different turbidity levels and pH values in comparison with starch