Removal of Water Hardness Causing Constituents Using Alkali Modified Sugarcane Bagasse and Coffee Husk at Jigjiga City, Ethiopia: A Comparative Study

Alkaline modified sugarcane bagasse and coffee husk were used for the adsorption of water hardness causing constituents (Ca+2 and Mg+2). The water hardness sample was collected using polyethylene bottle from Jigjiga city drinking water supply, Ethiopia. The adsorbents were characterized using FTIR and BET surface area techniques. The concentration of the constituents were determined using AAS Spectroscopy. It was found that, using the ABC and ACHC as an adsorbent, the maximum sorption capacity obtained for Ca and Mg hardness adsorption are 46.8 and 37.35, and 52.9 and 41.23 mg g-1 for ACHC and ABC respectively. Activated carbon filtration also depends on various parameters such as pH, contact time, adsorbent dose, temperature and initial Ca and Mg ion concentrations. The maximum recovery of the adsorbed calcium and magnesium was achieved in less than 200 minutes leading to 78% and 73% respectively. After treating synthetic water solution simulating an actual water stream with the alkali-modified bagasse and coffee husk, total hardness of the treated sample meets the required standard for drinking water, below 60 mg/L of CaCO3. Therefore, ABC is more suitable for the removal of hardness ions than ACHC from drinking water; and are considered as effective low cost adsorbents.