REMOVAL OF IRON AND MANGANESE FROM GROUNDWATER BY USING AERATION AND NATURAL SAND FILTRATION TECHNIQUES, METEKLE ZONE, BENISHANGUL GUMUZ REGIONAL STATE, WESTERN ETHIOPIA

Abstract

Groundwater is the most commonly used drinking water source for gilgel beles town. The concentrations of iron and manganese are commonly present in groundwater at worldwide. At gilgel beles town the concentrations of iron and manganese found in groundwater are beyond the standard, thus, concentrations of iron and manganese in domestic water supply may cause unpleasant taste, affect color and flavor of food and cause staining of different products also encourages bacterial growth in water distribution networks which affect the pipes transfer efficiency but in general they do not cause health problems in aerobic conditions they form sediments: dark brown (manganese) or brown-red (iron). Therefore, the study was to remove iron and manganese from groundwater supply of gilgel beles town by using aeration and natural sand filtration. Aeration and rapid sand filtration were commonly used methods for the removal of iron and manganese from groundwater. Aeration was carried out before filtration by spraying the water in the form of fine droplets into the air, thus creates a large gas-liquid interface for 𝑂2 transfer. This study was used different filtration materials for the removal of iron and manganese, including coarse sand, fine sand and supportive gravel. The pure water was passed through the filter beds easily for all the control units and experimental filter units. The filtrate from all the units were analyzed separately for iron and manganese concentration at a depth of 10, 15, 20, 25 and 30 cm of the filter run according to the standard methods. The initial concentration of iron and manganese sample raw water was 5.79 mg/L and 4.11 mg/L respectively. At the beginning of an experiment that was high concentration of iron and manganese in which was reduced by filtration was 0.09 mg/L for iron and 0.11 mg/L for manganese. The removal efficiency of iron and manganese during the experiment was good for coarse sand varying from 98.44% and 97.31% for iron and manganese respectively. Also, the correlation coefficient, 𝑅 2>0.994 for iron and 𝑅 2˃0.999 for manganese within filter media was achieved with a treatment at 30 cm of natural sand filter depth. It was also found that there was a regular pattern of increase the removal efficiency of iron and manganese from groundwater with the increase in natural sand filter depth. Therefore, natural sand is more effective in removing iron and manganese from groundwater and it is locally available