Liquid membrane system wastewater treatment

With the advancement of membrane technologies and engineering in the integration of MF, UF, NF, and RO membrane systems, and possibly a liquid membrane system, wastewater reclamation can provide high quality water for underground water replenishment and direct household nonpotable use, and source water for ultra-pure water applications. Membrane technology provides several advantages over conventional treatment processes ... 

Lin, S. H., Pan, C. L., Leu, H. G. (1999). Liquid membrane extraction of 2-chlorophenol from aqueous solution. Journal of Hazardous Materials 65 289-304. Raghuraman, B.J., Tirmizi, N.P., Kim, B.-S., Wiencek, J. M. (1995). Emulsion Liquid Membranes for Wastewater Treatment Equihbrium Models for Lead- and Cadmium-di-2-ethylheyl Phosphoric Acid Systems. Environmental Science and Technology 29 979-984. Liu, H. J., Wu, Q. S., Ding, Y. P., Liu, L. (2004). Biomimetic synthesis of metastable PbCrO4 nanoparticles by emulsion liquid membrane system with carrier and coupled treatment of Pb(II) and Cr(VI) wastewaters. Hrtij Chimica Sinica 62 946-950. 

Chapter 8, written by R. Tandhch, presents the field of wastewater treatment considering BLM, ELM, and SLM configurations of liquid membrane systems. 

The first known commercial membrane-based liquid-liquid extraction system involved extraction of by-products from a wastewater stream using an aromatic solvent [102]. Before the membrane system was installed, the entire wastewater stream had to be incinerated leading to high costs for the gas fired incinerator per year. The membrane system lowered the contaminant concentration to adequate levels before the biological wastewater treatment plant, and saved significant operating cost. 

The application of mercury is widespread in agriculture, for example, as insecticide in seed treatment, and different types of industry [60]. A promising method for the removal and preconcentration of mercury from wastewater has been the application of liquid membranes containing calixarenes as carriers [61]. A three-phase system for the extraction of Hg from industrial wastewater has been reviewed by Ersoz [62]. Models and implication of theoretical conclusions are presented. 

The main application of this technology for metal extraction will probably be in the treatment of effluents and wastewaters as shown by the many research papers that have been published. This is particularly true of the supported liquid membrane because of the many modules required to treat significant volumes of feed solution. This then creates a large capital expenditure, aud, although lifetimes of polymeric membranes have now been increased considerably, the initial outlay will probably be too great for the value of any benefits or metal recovered. However, if this process can be used for high-value products, then the expenditure can be more easily justified— hence, the potential use of such systems for recovery of pharmaceutical compounds. 

This review covers recent advances in the theory for emulsion liquid membranes (ELMs) briefly and in ELM applications in more detail. In the theory, the state-of-the-art models for two types of facilitation for ELMs are discussed. In the applications, significant advances have been made recently. Commercial applications include the removal of zinc, phenol, and cyanide fi om wastewaters and in well control fluid. Potential applications include wastewater treatment, biochemical processing, rare earth metal extraction, radioactive material removal, and nickel recovery. The ELM systems for these applications are described. 

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