1. 1. Faculty of Agricultural and Environmental Science, University of Rostock, Justus Von-Liebig Weg 6, 18059, Rostock, Germany
2. 2. School of Chemical Engineering, Jimma Institute of Technology, Jimma University, P.O.Box 378, Jimma, Ethiopia.
3. Faculty of Civil and Environmental Engineering, Jimma Institute of Technology, Jimma University, P.O.Box 378, Jimma, Ethiopia
4. Faculty of Agricultural and Environmental Science, University of Rostock, Justus Von-Liebig Weg 6, 18059, Rostock, Germany