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Treatment of heavy metals from industrial wastewaters using hollow fiber supported liquid membrane
Author(s)
Lothongkum, A. W.
Pancharoen, U.
Prapasawat, T.
Date Issued
January 1, 2013
Type
Book Chapter
Abstract
The challenge for today-wastewater-treatment technology is due to shortage of water resources, increasing of wastewater disposal costs, more stringent water quality criteria and environmental requirements as well as cost effective aspect. In stead of the end-ofpipe treatment, waste streams can be substantially eliminated or reduced by process modifications or by the availability of more efficient and chemical-free processes. Generally, the contaminants in wastewaters such as soluble organics, suspended solids, trace organics or heavy metals and their magnitude depend on products manufactured, the nature of the industry and process operations whether they are batch or continuous. It is significant to note that heavy metals should be removed in pretreatment prior to any biological treatment because they are perhaps toxic to the biological process and will accumulate on the biological sludge, resulting in difficulties of selecting sludge-disposal options. Heavy metals of major concern due to their acute or chronic toxicities or both. Such heavy metals are mercury, cadmium, lead, chromium, nickel, copper, manganese, zinc and iron. Because many heavy metal salts can dissolve in water, the traditional treatment methods such as chemical precipitation, precipitation-coagulation, adsorption, cementation, solvent extraction, electro-deposition and ion exchange have been deployed to remove them from contaminated water. However, these methods have disadvantage of sludge disposal and particularly are not effective for wastewater of a very low metal concentration. Recent developments in membrane technology have made increasing numbers of water treatment alternatives. Membrane processes become popular over the past 20 years and are progressively more viable because they are a proven and reliable method to overcome such disadvantages of the traditional treatment methods. The membrane additionally makes the process very compact. Several membrane operations are used successfully in large-capacity systems or industrial scale. This chapter offers the readers (any scientist, whether in the membrane field or a beginner) a broad overview of using membrane processes for water and wastewater treatment, particularly the hollow fiber supported liquid membrane (HFSLM), one of liquid membranes in supported structures. The hollow fiber modules have the highest surface area-to-volume ratio among other membrane modules. It is a favorable alternative for a relatively low-contaminantsconcentration system. HFSLM can separate toxic ions from wastewaters or recover valuable ions with high selectivity allowing their reuse. It contributes outstanding characteristics of simultaneous extraction and stripping of low-concentration target species in one single stage, non-equilibrium mass transfer, low energy and chemicals (extractant and solvent) consumed, which is of great importance and in accordance with the principles of green chemistry. In the end of the chapter, our up-to-date works applying HFSLM for both environmental and economic benefits are shown in detail, i.e., - selective recovery of Ni(II) from wastewater of stainless steel-cold rolled plate process; - selective extraction of Cr(VI) from spent pickling solution of stainless steel-cold rolled plate process; - treatment of arsenic ions from produced water; - selective removal of HgCl4 2- from produced water by TOA. © 2012 by Nova Science Publishers, Inc. All rights reserved.
Citation
Water Treatment Processes, 300-332, 2013