Slow Sand Filtration: A Simple Technology for Iron and Manganese Removal

摘要

The most common system used in Egypt for iron and manganese removal is based onrnoxidizing of them with chemical agents followed by rapid filtration. The performance of slowrnsand filtration technology as a biological treatment process for removal of iron andrnmanganese was investigated.rnA pilot-scale slow sand filter was tested using iron and manganese rich groundwater.rnThe pilot was operated with different rates as well as different influent concentrations of ironrnand manganese. The mean values of iron and manganese removal efficiencies were 94 % andrn99 % for manganese and iron respectively.rnBacterial and algal biomass development within the top layer of the sand andrnShmutzdecke are the key factors for removal of iron and manganese. Gallionella, Bacillus andrnPseudomonas were the dominant bacteria as well as Nitzschia and Stigeoclonim were therndominant algae found in the system. Pre-aeration is a primary important step, assist oxygenrnproduction and enhance the aerobic mechanisms involved in the bioremoval of iron andrnmanganese.rnThis system combines simple, low cost operation and maintenance with high iron andrnmanganese removal efficiencies. Thus constituting a technology which is particularly suitedrnto small waterworks.