The objective of the work presented here was to investigate the catalysing effect of iron oxyhydroxide on the redox reaction between ferrous iron and chromate. This was done in a bench-scale upflow reactor containing an expanded sand medium (fluid-bed reactor), where continous chemical addition, reaction and solid-liquid separation take place. Removal efficiencies of chromate in excess of 99% were attainable on spiked tapwater corresponding to an outlet concentration of 0.01 mg/l. Chromate polluted groundwater from a fly-ash disposal site was treated in the first full-scale plant (3 m3/h) with good results as well. The waste product generated by this method is a very compact granulate with a specific density of approx. 3 kg/l and low water content. Operation of the compact plant is simple and chemicals cost very little (approx. US D 1/400 per m3). The method (patent pending) is recommended for remediation purposes, but may also be applied in treatment of industrial wastewaters.
Henrik Aktor; Continuous high-rate removal of chromate in a fluidised bed without sludge generation. Water Sci Technol 1 October 1994; 30 (7): 31–40. doi: https://doi.org/10.2166/wst.1994.0298
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