How it works to clean groundwater contamination
Cleanit LC is most suitable for adsorptive media filter process with up-flow operations. The media is packed in vertical cylindrical columns and water is fed from the bottom. Depending on the contaminant type, concentration, and water characteristics, the empty bed contact time (EBCT) for the filter media ranges from 2 to 30 minutes. Although the media has a long effective cycle, it can be easily regenerated in the column by using processes such as media fluffing or media reconditioning. After the media is completely exhausted, we take it back for disposal.
Cleanit LC is an innovative water treatment technology which uses engineered iron-based media capable of removing multiple contaminants in a single step from groundwater, drinking water and industrial wastewater. The major removal mechanism is reductive adsorption similar to that of zero valent iron (ZVI). Target contaminants in soluble form, such as Hexavalent Chromium [Cr(VI)] are adsorbed on the surface of the media, and chemically reduced to more stable compounds, e.g. oxyhydroxide forms, by reaction with the ZVI fraction of the media. As a result of the reaction, iron is dissolved into the water in the form of Fe(II), which is either adsorbed again on the Cleanit LC media and further oxidized to Fe(III) by the reduction of adsorbed Cr(VI), or directly reacts with Cr(VI) in aqueous phase and precipitates as Fe(III). Consequently, insoluble Cr(III) and Fe(III) both remain on the media.
The unique surface morphology and high surface area of the Cleanit LC media make this multiple removal mechanism possible. According to a laboratory analysis, the BET surface area of the Cleanit LC media is 4.42 m2/g with a particle size less than 150 µm, which is at least 100 times greater than conventional ZVI media with an identical particle size. Additionally, SEM analysis reveals a sponge-like surface morphology of the media, which appears to have numerous reticulated porous structures developed during the manufacturing process. The Cleanit LC media is also a cost-effective treatment solution, which has a media life typically greater than one year on most applications before replacement. After replacement, the media can be sent back to Höganäs (pending TCLP approval). The media has high operating capacity across a wide range of pH and flowrates.
Höganäs’ commercial Cleanit LC systems for the removal of heavy metals consist of a sand filter for the removal of suspended solids followed by Cleanit LC columns in series and finally a post treatment filter for the removal of any dissolved iron. Auxiliary equipment consists of holding tanks for equalization and maintenance cycles, pumps, instrumentation and chemical dosing (if required). The maintenance cycles required for the Cleanit LC process are periodic media washing and media reconditioning (MR) cycles.
Cleanit in practice
See the results for Cleanit LC from full-scale operations and pilot studies in Brazil and California.
One of the leading water plants in California, USA.