Enhanced Slow Sand Filter for Iron and Manganese Removal: Using Fabrics

摘要

Last years, slow sand filtration has been proved to be a simple low cost technology for iron and manganese removal without the addition of chemicals. Application of nonwoven fabrics in the slow filter has been studied before and found to be advantageous in treating turbid surface water. In this research, pilot-scale slow sand filters were tested using iron and manganese rich groundwater (Fe ＞ 1.0 mg/L and Mn ＞ 4.0 mg/L). The pilot plant comprises a tray aerator followed by two identical slow sand filters were working in parallel. A comparative study has been conducted where; one filter was tested using nonwoven polyester fabric while the other filter was tested without fabrics. A mechanically bonded nonwoven fabric with low punching density, high surface hardness and high mass per unit of area was found to be suitable for this application. Results obtained from the comparative study showed that the thickness of the sand removed during the filter cleaning has been reduced by 1.5 cm, the run length of the filter with fabrics has been increased by 50 %, iron and manganese removal efficiencies were generally 96 % and 99 % respectively on average for both filters and the removal of turbidity was almost the same. Thus constituting a high good potential of using nonwoven fabrics in the slow sand filtration systems.