Continuous high-rate removal of chromate in a fluidised bed without sludge generation

Abstract

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.

Utilization of water clarifier sludge for copper removal in a liquid fluidized-bed reactor

“…The flow velocity has been found to be less than 3 m/h in a fixed-bed [15,16], which is low. Using an FBR has been studied to adsorb heavy metals from wastewater [14,17,18] and found that the velocity was 6-30 m/h. The flow rate in an FBR is higher than that in a fixed bed, and the adsorption time is reduced.…”

Continuous Adsorption and Recovery of Cr(VI) in Different Types of Reactors

“…Lopez et al (11) examined the efficiency of alginate beads containing Mycrocystis species for uranium and copper adsorption in a fluidized loop reactor and approximately 30−65% adsorption has been reported. Aktor (12) and Nielson et al (13) have highlighted the effective removal of metal ions in fluidized bed without sludge generation. Stirred tank reactors for successful removal of Fe, 3+ Pb, 2+ Cd 2+ and Cu 2+ had been investigated by Sag and Kutsal (14) and Ozer et al (15).…”

Removal of copper (II) by manganese-coated sand in a liquid fluidized-bed reactor

“…In recent years, the fluidized-bed reactor (FBR) technique process has been used as an alternative treatment method for heavy metal removal [10][11][12][13][14][15]. The process of crystallizing CaCO 3 in an FBR was applied in the softening of drinking water [10].…”