Iron and Manganese Removal Efficiency of Bio Sand Filter from Groundwater at Thottaveli Source, Mannar

Abstract

Iron and manganese are the elements in the groundwater which are required in small amounts. If the amounts of these elements are higher than the Sri Lankan Standard of (SLS) permissible level, removal is necessary. In Mannar Thottaveli area, there are nine inter connected wells that were used to supply the drinking water to Erukkalampitty tower, in which four are showing higher Mn and Fe levels than the permissible level from the 2012 January. Hence the pumping has been stopped from the above mentioned wells. From 2012 June - to date, other 4 wells are selected for the water supply. The main objective of this study was to propose a method to remove the Fe and Mn from Thottaveli source and to evaluate the efficiency of removal of the bio sand filter. Water samples were collected from April to July 2013. Water quality parameters of raw water were tested. A preliminary study was conducted using a biosand filter to ensure the efficiency and effectiveness of the bio sand filter. Collected water samples from Thottaveli were used for the filtration treatment. After the filtration by bio sand filter, all the chemical parameters of filtered water were tested. The results indicated that the above water source should not be used to supply further as the concentration of Mn and Fe were 0.7 and 1.5 mg/1, respectively. The percentage of removal efficiency varied from 90 to 95 % for Fe and 78 to 98 % for Mn. The average removal efficiency percentage values were 94% and 91% , respectively for Fe and for Mn. The concentrations of Fe and Mn in filtered water were less than the permissible level of SLS in all the cases. There were no any significant differences between raw and filtered water in other chemical parameters and it could be used for drinking purpose. Hence, biosand filter can be recommended for home level usage to remove Fe and Mn.