Microfiltration economics

A. E. Ostermann and E. Pfleiderer, "AppHcation of the Principle of Cross-Flow in SoHd/Liquid Microfiltration," in the Proceedings of the Symposium on Economic Optimi tion Strategy in SolidjFiquid Separation Processes, SocifitH Beige de Filtration, Louvaine-la-Neuve, Belgium, Nov. 1981, pp. 123-138. 

Whereas many of these technologies are not really new, they have never had the regulatory and economic justification for their use in metallizing. Each of these general methods has many variants. Some may be directed to waste treatment, some to recycle, and some to reclaim. An example is filtration, used to prevent release to air of zinc particles from flame spraying, microfiltration of cleaners to extend hfe, in combination with chemical precipitation to remove metal particles from wastewater, and many other uses. 

Brief Examples Microfiltration is the oldest and largest membrane field. It was important economically when other disciphnes were struggling for acceptance, yet because of its incredible diversity and lack of large apphcations, it is the most difficult to categorize. Nonetheless, it has had greater membrane sales than all other membrane applications combined throughout most of its histoiy. The early... 

Large Plants The economics of microfiltration units costing about ilO " is treated under ultrafiltration. When ceramic membranes are used, the cost optimum may shift energy consumption upward to as much as 10 kWh/m. ... 

Cross-flow is the usual case where cake compressibility is a problem. Cross-flow microfiltration is much the same as cross-flow ultrafiltration in principle. In practice, the devices are often different. As with UF, spiral-wound membranes provide the most economical configuration for many large-scale installations. However, capillary devices and cassettes are widely employed, especially at smaller scale. A detailed description of cross-flow microfiltration had been given by Murkes and Carlsson [Crossflow Filtration, Wiley, New York (1988)]. 

Economics Micronltration may be the triumph of the Lilliputians nonetheless, there are a few large-industrial applications. Dextrose plants are very large, and as membrane filtration displaces the precoat filters now standard in the industry, very large membrane microfiltration equipment will be built. 

Sterilization can be accomplished by several means, including heat, chemicals, radiation (ultraviolet (UV) or y-ray), and microfiltration. Heat is widely used for the sterilization of media and fermentation equipment, while microfiltration, using polymeric microporous membranes, can be performed to sterilize the air and media that might contain heat-sensitive components. Among the various heating methods, moist heat (i.e., steam) is highly effective and very economical for performing the sterilization of fermentation set-ups. 

Despite the limited volumes that can be treated before a filter must be replaced, microfiltration is economical because the cost of disposable cartridges is low. Currently, a lO-in.-long pleated cartridge costs between US 10 and US 20 and contains 0.3-0.5 m2 of active membrane area. The low cost reflects the large numbers that are produced. 

Food and beverage processing represents an expanding area for process-scale microfiltration. Already in place are clarification systems for wine and beer, sugar, and gelatin, replacing existing practices such as diatomaceous earth filtration. Less attractive economically are miscellaneous waste treatment applications, for which microfiltration is often a sophisticated but expensive alternative. 

The selection of the most suitable enzyme for a certain purpose mainly depends on its biocatalytic characteristics. Once a correct choice has been made, it is important to minimize the expenses associated with the enzyme use, as the economic feasibility of enzymatic processes is likely to depend on the cost of the enzyme production. In this context, several authors showed that the performance of various peroxidase processes was independent of enzyme purity [1,2], even suggesting that the crude enzyme was protected from inactivation [3, 4]. Microfiltration and subsequent ultrafiltration stages are sufficient to separate biomass and concentrate the enzyme for an economically viable operation [2, 5]. 

Only a few reports are available on the preparation of MFGM from commercially available sources and the opportunities to exploit fully the utilization of MFGM as a functional material are so far limited by the lack of available products and commercially feasible preparation methods. The development of methods for the extraction of MFGM from buttermilk through microfiltration may increase the opportunity to produce this ingredient on a commercial scale. On the other hand, before the economics of such processes can be appreciated, the unique functionality of MFGM isolates needs to be understood better. 

Singh N and Cheryan M. Process design and economic analysis of a ceramic membrane system for microfiltration of com starch... 

Ebrahim, S., Bou-Hamed, S., Abdel-Jawad, M., and Burney, N., Microfiltration system as a pretreatment for RO units Technical and economic assessment. Desalination, 109, 165, 1997. 

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