ASSESSMENT OF HEAVY METALS CONTAMINATION IN GROUNDWATER AND ADSORPTIVE REMOVAL OF IRON, MANGANESE, CADMIUM, COPPER AND ZINC USING PEAT MOSS: THE CASE OF KEMBATA TEMBARO ZONE

Abstract

Heavy metal contamination is one of the most significant health issues. Heavy metals in groundwater were assessed and analyzed using atomic absorption spectrometer. The HPI, Cdeg and HEI indices were greater than their critical values of pollution indices. The result showed that Fe 2+ and Mn 2+ are the major groundwater contaminant's in the study area. Chemicals are mostly used to purify contaminated water. Adsorptive removal is most important to reduce heavy metals in water to acceptable levels and to minimize the cost of chemicals and health effects of chemicals. Thus, research was carried out to observe the effect of Sphagnum moss (peat moss) as non-chemical natural adsorbent. The Sphagnum moss was obtained from SNNPR, Kembata Tembaro Zone, Hambericho Mountain. The 500 and 1000 mg of peat moss were used to examine the effectiveness of peat moss to remove different concentration of iron, manganese, cadmium, copper and zinc. For removal of iron, manganese, cadmium, copper and zinc from contaminated boreholes and shallow wells water, batch experiment were employed. The contact time, pH, temperature and adsorbate concentration effects were studied during the adsorption of iron, manganese, cadmium, copper and zinc. The relationship between pH, time and concentration required adsorbing 5-15 mg/L of iron, manganese, cadmium, copper and zinc from the aqueous solution were observed. The average adsorption (93.72%) result indicated that there was a reduction of iron, manganese, cadmium, copper and zinc concentration in the water samples at pH 6.0. The 1000 mg peat moss was effective to remove 96.3% of 5 mg/L of iron, at pH 6, with the contact time 60 minutes. Adsorption equilibrium was attained after 60ࡋ minutes of contact time and it was described by kinetics studies. From (R2) values Zn 2+ and Cd 2+ best fit Langmuir adsorption isotherm model. All of the tested metals best fit Freundlich adsorption isotherm model.The model should be developed for large-scale treatment using peat moss for effective water purification