Chemical membrane filtration

Intensive technologies are derived from the processes used for the treatment of potable water. Chemical methods include chlorination, peracetic acid, ozonation. Ultra-violet irradiation is becoming a popular photo-biochemical process. Membrane filtration processes, particularly the combination microfiltration/ultrafiltra-tion are rapidly developing (Fig. 3). Membrane bioreactors, a relatively new technology, look very promising as they combine the oxidation of the organic matter with microbial decontamination. Each intensive technique is used alone or in combination with another intensive technique or an extensive one. Extensive... 

Table 4 summarizes the efficiency of membrane filtration as preliminary treatment in the hybrid process to obtain regenerated water for industrial reuse. Working with the adequate cleaning cycle to avoid fouling and to keep a constant flux (10 1 min ) important reduction in suspended solids (90%) and turbidity (60%) of the wastewaters is achieved but there is no significant reduction of other chemical or physical parameters, e.g., conductivity, alkalinity or TDS, or inactivation of E. coli. 

S. Yao, A. G. Fane, J. M. Pope 1997, (An investigation of the fluidity of concentration polarisation layers in crossflow membrane filtration of an oil-water emulsion using chemical shift selective flow imaging), Mag. Reson. Imag. 15, 235. 

Different technologies have been developed in recent years to treat the wastewaters contaminated with heavy metals. Chemical precipitation, coagulation-flocculation, flotation, ion exchange, and membrane filtration can be employed to remove heavy metals from contaminated wastewater.6 However, they have inherent limitations in application mainly due to the lack of economical feasibility for the treatment of large volumes of water with a low metal concentration. Furthermore, the major disadvantage of conventional technologies is the production of sludge.9... 

Gravity separation Centrifugal separation Filtration Membrane filtration Coalescence Centrifugal separation Flotation Wet oxidation Thermal oxidation Biological oxidation (aerobic, anaerobic, reed beds) Chemical oxidation Activated carbon Wet oxidation Thermal oxidation... 

The separation of homogeneous catalysts by means of membrane filtration has been pioneered by Wandrey and Kragl. Based on the enzyme-membrane-reactor (EMR),[3,4] that Wandrey developed and Degussa nowadays applies for the production of amino acids, they started to use polymer-bound ligands for homogeneous catalysis in a chemical membrane reactor (CMR).[5] For large enzymes, concentration polarization is less of an issue, as the dimension of an enzyme is well above the pore-size of a nanofiltration membrane. 

Porter, M. C. In Handbook of Separation Techniques for Chemical Engineers, Schweitzer, P. A. (ed.) 2nd edn. (McGraw-Hill, New York, 1988). Membrane Filtration. 

The main techniques that have been used to dispose of industrial effluents include chemical precipitation, ion exchange, electrochemical processes, and adsorption onto various adsorbents and/or membrane filtration. Although all of these techniques are capable of removing heavy metals to some extent, adsorption by solid substrates is preferred because of its high efficiency, easy handling and cost as well as the availability of adsorbent. 

Coverage of thermal, chemical, surface, and mechanical properties of inorganic membranes includes discussion of pore diameter, thickness, and membrane morphology. You ll gain valuable insights into membrane modification, as well as the design and operation of membrane filtration units. 

Uses fewer chemicals than traditional membrane filtration processes. 

The SBP membrane filtration system concentrates contaminants and reduces the volume of contaminated groundwater, surface water, storm water, landfill leachates, and industrial process water. This hyperfiltration system consists of stainless steel tubes coated with a multilayered membrane, which is formed in-place using proprietary chemicals. The membrane filtration system can be used with an SBP bioremediation system or another technology as part of a treatment train. 

Since membrane filtration methods such as ultra filtration or nanofiltration can discriminate according to the size of a given molecule, they can easily be used to retain biocatalysts (which are macromolecules). For chemical catalysts additional procedures have to be applied mostly. Immobilization on a solid support is used... 

To use membrane filtration for residence time decoupling the molecular weight of the chemical catalyst has to be increased, for example, by binding the catalyst to a homogeneously soluble polymer [4]. This allows for separation of reactants and catalysts by size. Due to their similarity to biological catalysts, the term chemzyme (chemical enzyme) [5, 6] has been coined for these polymer-enlarged but still homogeneously soluble chemical catalysts (Fig. 3.1.2) [7]. 

In summary, water can be a source of contaminants. If the raw material (drinking water) complies with the quahty parameters established by authorities, contaminants still present can be eliminated by usual water purification processes available to the pharmaceutical industry. While distillation and reverse osmosis provide water with the quality specifications for purified water and highly purified water, WFI is generally obtained by membrane filtration (associated with another purification process) not only because of chemical contamination but mainly because of sterility requirements. 

The collection of small amounts of very fine precipitates is the basis for many chemical and biochemical analytical procedures. Membrane filtration is an ideal method for sample collection. This is of great advantage in the... 

The critical issue for a successful RO plant is pretreatment. Long-term operating experience proves the viability of continuous MF/UF pretreatment of RO for the desalination of a wide variety of water sources. MF/UF has proven to simplify and reduce the costs of traditional pretreatment, comprised of deep-bed media filters combined with chemical treatment. MF/UF produces filtrate of a consistent quality almost irrespective of fluctuations in feed-water quality. In the last five years, RO-membrane improvements, combined with the use of membrane filtration for pretreatment, have halved the cost of advanced treatment and are now more widely used for the reuse of municipal wastewater. 

Concentration Units. Typical concentrators for rinsing solutions are membrane filtration units, which split the feed into diluate and concentrate streams, meaning purification and recovery, respectively [106], Both nanofiltration and reverse osmosis might be applied, depending on the physico-chemical properties of the solutes. 

Removal of mercuric species in aqueous solutions is difficult because they are hard to be bio- or chemically degraded. At high concentrations, mercury can be removed from the solution by membrane filtration, precipitation with chemicals, ion exchange, adsorption, and reduction (Botta et al., 2002). However, these methods are much less efficient and very expensive for concentrations lower than 100 mg (Manohar et al., 2002). 

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