Chromium removal and recovery

Ho, W.S., Supported liquid membrane process for chromium removal and recovery, US Patent No. 6,171,563, 2001. 

SUPPORTED LIQUID MEMBRANES WITH STRIP DISPERSION 28.2.1 Chromium Removal and Recovery... 

Electrolytic methods have been applied to the treatment of other metal waste streams generated in the electroplating or metal finishing industries. Pollution engineering processes have been designed and implemented for the removal of hexavalent chromium, trivalent chromium, nickle, copper, zinc and cadmium.Besides the Edwards patent, there seems to be no documentation of electrolytic methods for removal and recovery of mercury metal from waste streams. 

Ho, W.S.W. and Poddar, T.K. (2001) New membrane technology for removal and recovery of chromium from waste waters. Environmental Progress, 20, 44. 

A. Esmaeili, A. Mesdaghinia, and R. Vazirinejad, Chromium(III) Removal and Recovery from Tannery Wastewater by Precipitation Process, American Journal of Applied Science, 2(10), 1471-1473 (2005). 

W. S. Ho and K. Poddar, New Membrane Technology for Removal and Recovery of Chromium from Waste Waters, Environ. Prog., 20(1), 44-51 (2001). 

In what follows the methodology for the selection of the operating conditions of a nondispersive solvent extraction process will be developed. As an example the removal and recovery of Cr(VI) from an indnstrial effluent of a surface treatment plant will be considered. The kinetic modeling including the extraction reactions. Equation (6.17) and Equation (6.22), and the mass balances of chromium compounds to the three fluid phases and considering the hollow fiber modules and the homoge-neization stirred tanks. Equation (6.30) through Equation (6.50) were described in Sections 6.3 and 6.4. 

This chapter reviews recent advances in SLMs with strip dispersion for removal and recovery of metals, including chromium, copper, zinc, cobalt, and strontium, from waste-waters and aqueous streams. This chapter also discusses potential applications of SLMs for removal and recovery of antibiotics including peniciUin G and others. 

The sodium chlorate manufacturing process can be divided into six steps (/) brine treatment 2 electrolysis (J) crystallisation and salt recovery (4) chromium removal (5) hydrogen purification and collection and (6) electrical distribution. These steps are outlined in Figure 3. 

The Lewis ENVIRO-CLEAN process removes and recovers metals such as chromium, copper, nickel, mercury, lead, zinc, iron, and cadmium and has effectively demonstrated that it can treat a matrix of multiple metals in a single stream with positive results. The process treats wastes from wood preserving, metal finishing, mining, surface and groundwaters. The two-step process uses granular-activated carbon and electrolytic metal recovery to yield a salable metallic by-product. 

Metal Value Recovery from Metal Hydroxide Sludges Removal of Iron and Recovery of Chromium... 

LEMs have been applied for the separation and recovery of a host of different compounds. Previous efforts have been primarily focused on the recovery of metal ions from aqueous solutions (including copper, zinc, chromium, mercury, uranium, nickel, and iron (3)) and the removal of organic compounds from wastewater (14-17). 

EnvirOTimental trends are having an impact on electrical applications. Waste legislation includes WEEE (Waste of Electrical and Electronic Equipment) directive 2002/%/EC which holds producers responsible for collection and recovery of materials at end of Ufe. Additionally, materials that contain bromine-based flame retardants must be removed from the waste and handled separately. In restrictions on use of hazardous substances (ROHS) directive 2002/95/EC, the use of various hazardous materials is restricted. These include lead, mercury, cadmium, hexavalent chromium, polybrominated biphenyls, and polybrominated diphenyl ether. Since the introduction of Blue Angel in Germany in 1978, several other eco-labels have been implemented. These include TCO (Sweden), Nordic Swan, Milieukeur (Netherlands), and the EU Ecolabel. The general purpose of these labels is to provide cmisumers with information relating to the environmental impact of the products they purchase. 

The suitability of gas absorption as a pollution control method is generally dependent on the following factors 1) availability of suitable solvent 2) required removal efficiency 3) pollutant concentration in the inlet vapor 4) capacity required for handling waste gas and, 5) recovery value of the pollutant(s) or the disposal cost of the unrecoverable solvent. Packed-bed scrubbers are typically used in the chemical, aluminum, coke and ferro-alloy, food and agriculture, and chromium electroplating industries. 

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