Groundwater hardness characterization is very important for suitable softening technology selection and development. Haramaya University (HU) is one of the Ethiopian public University that relies on groundwater for domestic and academic purposes. Lime scaling and pipe clogging is the main challenges of the HU’s water supply system. This study aimed to characterize groundwater hardness and identify an appropriate centralized softening technology. Samples from eight boreholes (BHs) were analyzed to identify hardness causing parameters, hardness type, and scaling and corrosion potential. Softening technologies were evaluated based on treatment potential and feasibility factor criteria, and the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) was applied to select the ideal softening technology. Result showed that concentrations of Ca 2+ , Mg 2+ , HCO 3 , Cl - , and SO 4 2- ranged from 75 to 107 mg/L, 41–60 mg/L, 275–360 mg/L CaCO 3 , 7.5 to 17.5 mg/L, and 2 to 4.6 mg/L, respectively, resulting in very hard groundwater (>300 mg/L CaCO 3 ) at HU. The Langelier Saturation Index (LSI), Aggressive Index (AI), and Larson–Skold Index (LS) indicated scaling potential in all water samples. The Ryznar Stability Index (RSI) showed slight corrosion potential in BH1 and BH2, neutral indications in BH3, BH4, BH5, and BH6, and scaling potential in BH7 and BH8. Based on the analysis of softening technology alternatives, Reverse Osmosis (RO) was selected as the suitable technology for developing a centralized softening technology at HU. This finding is very important for HU and others facing similar challenges.
Futasa et al. (Tue,) studied this question.