Turbidity removal is a meaningful activity in the water treatment system, and it is an indicator of water quality. With this, natural coagulants are desirable and economical ways of removing water turbidity. The purpose of this study was to investigate the turbidity removal efficiency of Odaracha soil from river water. A coagulation experiment was carried out using a standard procedure for a jar test. 300 mL of water sample was added into a beaker by adjusting the water pH to the desired value. Different coagulant doses are added and mixed for 2 minutes by 250 rpm, then agitated for 10 minutes by 45 rpm. Finally, the sample was unflustered for different settling times. Response surface methodology (RSM) was also applied to optimize the process and estimate the interaction influence of the operating variables. According to the experimental result of this study, at the optimum condition (pH 7, 0.5 hrs. settling time, and 3 g/L of coagulant dose), the turbidity removal efficiency of Odaracha was 88.13%. In contrast, the predicted turbidity removal efficiency was 90.54%, which indicates the consistency between the actual and the anticipated results. Correspondingly the R2 value (0.9922) confirmed a high correlation between the real and predicted values. Generally, the quadratic model’s actual and predicted results confirmed the turbidity removal capability of Odaracha and the significant effects of all the individual parameters and their interaction effects (except the interaction between the dose and settling time).

Yohanis Birhanu is a lecturer in the applied chemistry department of Jigjiga University, Ethiopia. He was awarded his Master’s degree in the field of Environmental Science at Ambo University in 2012. Currently, He is a Ph.D. candidate prepared to defend his Ph.D. dissertation at the Center for Environmental Science, Addis Ababa University, Ethiopia. Yohanis Birhanu was the general manager of Knowledge Excellence Center (KEC) from Sept 2017 to Jan 2019. Yohanis’s research focuses on water quality management, sustainable waste management, resource recovery, and environmental analysis. He published several research articles in reputable international journals.