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In this study natural coagulant is used in addition to alum. The natural coagulant used in this study is schanginia, which is considered as available and low cost material. The experiments are performed in three stages at the same operating conditions. The first stage involves using alum alone, the second one is carried out using natural coagulant (schanginia), and third stage involves using a mixture alum and natural coagulant (schanginia) with the same quantity for each one. The optimum doses of alum, schanginia and mixture of alum and schanginia are (40, 50 and 60) mg/l, which have accomplished turbidity removal of (91.92, 73.74 and 76.77) %, respectively. According to these results, schanginia can be used as a coagulant alternative to alum or can be used with alum in water purification, because it gives satisfactory results in turbidity removal. In addition, it is a low cost material and it can be considered as an effective coagulant, taking into account the value of pH, dosage of coagulant, rapid and slow mixing time. The results indicate that the removal efficiency is affected by doses of coagulant. However, the experimental results at the same operating conditions, reveal that the removal efficiency of turbidity is higher for alum alone compared to natural coagulant (schanginia) and a mixture of alum and schanginia.