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 foriron and manganese removal without the addition of chemicals. Application of nonwovenfabrics in the slow filter has been studied before and found to be advantageous in treatingturbid surface water. In this research, pilot-scale slow sand filters were tested using iron andmanganese rich groundwater (Fe ＞ 1.0 mg/L and Mn ＞ 4.0 mg/L). The pilot plant comprises atray aerator followed by two identical slow sand filters were working in parallel. Acomparative study has been conducted where; one filter was tested using nonwoven polyesterfabric while the other filter was tested without fabrics. A mechanically bonded nonwovenfabric with low punching density, high surface hardness and high mass per unit of area wasfound to be suitable for this application. Results obtained from the comparative study showedthat 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 manganeseremoval efficiencies were generally 96 % and 99 % respectively on average for both filtersand the removal of turbidity was almost the same. Thus constituting a high good potential ofusing nonwoven fabrics in the slow sand filtration systems.