Disinfection commercial applications

The oxidative degradation of organic pollutants in water and air streams is considered as one of the so-called advanced oxidation processes. Photocatalytic decomposition of organics found widespread industrial interest for air purification (e.g., decomposition of aldehydes, removal of NO , ), deodorization, sterilization, and disinfection. Domestic applications based on Ti02 photocatalysts such as window self-cleaning, bathroom paints that work under illumination with room light, or filters for air conditioners operating under UV lamp illumination have already been commercialized. Literature-based information on the multidisciplinary field of photocatalytic anti-pollutant systems can be found in a number of publications, such as Bahnemann s [237, 238] (and references therein). 

This technology is currently commercially available from the MIOX Corporation, an affiliate of Los Alamos Technical Associates, Inc. While the MIOX system for disinfection applications is fully commercialized, applications for environmental remediation and Resource Conservation and Recovery Act (RCRA) waste treatment are still in the early stages of development. 

The theoretical basis of light-induced antimicrobial treatment is described, followed by examples of its application for the cleaning and disinfection of surfaces. All available information supports the idea that PDT could offer a very efficient and cost-effective way to combat microbial contamination of foods. The advantages and pit-falls of the technique are discussed. Directions of future research needed for bringing the technology to commercial reality are identified. 

The majority of currently accepted applications of PDT are in the medical area. MB has been widely used by several European blood transfusion services for the decontamination of blood plasma. Ready-to-use reagents and automatic systems are commercially available for photodynamic plasma disinfection from Baxter Healthcare and Maco Pharma (UK). It has been shovm previously that the PDT of plasma is particularly effective in the inactivation of enveloped viruses such as HIV, influenza, herpes simplex. West Nile virus, and others (Williamson et al., 2003). 

Results of this study confirm the expected improved recoveries of trace organics with membranes more selective and more highly cross-linked than the classical cellulose acetate membrane. Improved recoveries were predicted from literature data reported for similar membrane types. In light of these results, cellulose acetate should no longer be considered for applications such as these. Further improvements in recovery can be expected as developmental membranes with more highly selective barriers are brought into commercial use. Each new membrane type considered for use on disinfected waters should be evaluated for sensitivity to common disinfectants (oxidants). Both decreased selectivity and potentially troublesome chemical breakdown products should be considerations under these conditions. Although the cellulose acetate and FT-30 composite membranes did not prove to be particularly sensitive to chlorine, many commercially available... 

Pentoses contained in hemicellulose are used to produce furfural, a useful industrial chemical, used as a solvent for resins and waxes and in petrochemical refining. It is also used as a feedstock for a range of aromatic substances (it has an almond odour) including preservatives, disinfectants and herbicides. Furfural can be converted to furfuryl alcohol and used to make resins for composite applications with fibreglass and other fibres. These are of interest in the aircraft component and automotive brake sectors. Furfural is commercially derived from acid hydrolysis of waste agricultural by-products, such as sugarcane bagasse, com cobs and cereal brans. Around 450 000 tonnes is produced by this method per year. 

The reduction of aqueous chlorine (HOC1) to chloride by Fe° and other ZVMs [Eq. (5)] has long been known as a major contributor to the decay of residual chlorine disinfectant during distribution in drinking water supply systems that contain metal pipes (e.g., Ref. 82). This reaction can, however, be turned to advantage for the removal of excess residual chlorine, and a variety of proprietary formulations of granular ZVMs are available commercially for this purpose (e.g., KDF Fluid Treatment, Inc. Three Rivers, MI). This application is sometimes called dechlorination, but should not be confused with the dechlorination of organic contaminants, which is discussed below. 

Obtaining insight into charge transfer processes is important in order to improve the photoconversion efficiencies in semiconductor-based nanoassemblies. The principles and mechanism of photocatalytic reactions in advanced oxidation processes can be found in earlier review articles [40-42]. Technological advances in this area have already led to the product development for a variety of day-to-day operations. Commercialization of products such as self-cleaning glass, disinfectant tiles and filters for air purification demonstrate the initial success of nanosystems for environmental applications [43]. 

Chlorine is an efficient disinfectant as well as an oxidizing agent, and perhaps is the most frequently used chemical by environmental engineers and scientists since 1800s. The oldest water treatment facilities used only chlorine for water disinfection, which became the foundation of our industrial development. Today chlorine has been used in various forms for sanitary, commercial, industrial, and military applications. This chapter is a sister chapter to the following book chapters in the Handbook of Environmental Engineering series ... 

At millimolar levels of molecular chlorine, the reaction goes to 99% completion in a matter of a few seconds. Above pH 4.4, essentially no molecular chlorine remains in aqueous solution. Hypochlorous acid is a weak acid (pKa approximately 7.5) and thus, near neutrality, both the protonated form and the anion occur at appreciable levels. HCl-free solutions may be prepared by adding salts such as sodium hypochlorite (NaOCl, commercially available as a stabilized 5.25% [0.7 M] solution as a fabric bleach). Either chlorine gas or hypochlorite solutions can be used in large-scale water chlorination applications. In addition to water treatment, chlorine is also used as a disinfectant for beef, pork, and poultry carcasses and also as a bleaching agent for paper pulp and cake flour (Wei et al., 1985). The disinfecting ability of aqueous chlorine is closely associated with its vigorous oxidant character the redox potential for the reactions... 

It is found in Japan, the Korean peninsula, and China. Another name for this plant is kujin, which literally means the bitter root. The Chinese characters for this plant also point to the fact that althongh this root may taste bitter, it has snperior medicinal qualities. The roots of this species are commercially available as the generic Kosam in Korea, and it has been apphed freqnently in folk medicine as an antipyretic, analgesic, anthelmintic, and a stomachic drag. Externally the root has been applied to treat rashes and a variety of other ailments. Although hitherto it has not found widespread application in cosmetic prodncts, it is used to a certain extent for its moisture-retention and disinfectant properties. ... 

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