Potential plant leaves as sustainable green coagulant for turbidity removal

Chemical coagulation–flocculation has been used widely in water and wastewater treatment. In the present study, green coagulant was investigated. The role of Iraqi plants was examined to remove turbidity by using kaolin synthetic water. Thirteen selected plants were prepared as powdered coagulant. The experiment was run based on coagulant mass varied from 0 to 10,000 mg/L for each plant with a rapid mixing speed of 180 rpm for 5 min, slow mixing speed at 50 rpm for 15 min and settling time for 30 min. The seven best green coagulants are Albizia lebbeck (L.), Clerodendrum inerme (10,000 mg/L), Azadirachta indica, Conocarpus lancifolius, Phoenix dactylifera (5000 mg/L), Dianthus caryophyllus (3000 mg/L) and Nerium oleander (1000 mg/L) with turbidity removal rates of 39.3%, 51.9%, 67.2%, 75.5%, 51.0%, 52.6% and 57.2%, respectively. The selected seven plants that were used as green coagulants are economically feasible to achieve the highest turbidity and removal of other compounds.