Nonthermal treatment

Ascorbic acid is probably the most labile bioactive compound in fruit juices and fruit and vegetable pieces, as we described in the first part of this chapter. Retention of this phytochemical after the nonthermal treatments ranged from 47% to 100%, depending on the intensity of the applied treatment and the product. For example, the greatest losses of vitamin C were found in fresh-cut red lettuce and melon treated with IR and HHP (Fan and others 2008 Wolbang and others 2008), respectively. However, the use of gamma radiation in various vegetables retained 100% of their total ascorbic acid content (Fan and others 2008). 

The typical approach to nonthermal stabilization for waste streams containing inorganic contaminants is chemical immobilization. In this approach, low-cost stabilizing chemicals are added to the waste stream, and contaminants are chemically treated to render them harmless. Such a treatment, if conducted at ambient temperature, is ideal for handling high waste volumes at low cost, provided the waste volume is not increased excessively during the treatment (higher volume may raise the transportation and disposal costs). Thus, the major constraint for nonthermal treatment is that the waste volume increase be kept to a minimum. 

Wuytack, E.Y., Phuong, D.T., Aertsen, A., Reyns, K.M.F., Marquenie, D., De Ketelaere, B., Masschalk, B., Van Opstal, I., Diels, A.M.J., and Michiels, C.W. 2003. Comparison of sublethal injury induced Salmonella enterica serovar Typhimurium by heat and by different nonthermal treatments. Journal of Food Protection 66 31-37. 

Physical modification involves thermal treatments such as plasma or nonthermal treatments like application of electric discharge, ultrasound, ultraviolet, or high-frequency cold plasma to the fiber surface. Stmctural and surface properties of the fibers are changed by these treatments, which result in improved mechanical bonding to polymers. These treatments are apphed to separate the fiber bundles into individual filaments and modify the fiber surface for more compatibility with the matrix in the composite [6]. If separation of the fiber bundles is desired, methods like steam explosion and thermomechanical processing are adopted. Methods like plasma (thermal) treatment, dielectric barrier techniques, or corona discharge (nonthermal) treatments (CDT) are anployed to modify the fiber surface. 

EPA rules allow nonthermal treatment of hazardous wastes in a tank on site without a hazardous waste permit, as... 

Wuytack EY, Duong Thi Phuong L, Aertsen A, et al. 2003. Comparison of sublethal injury induced in Salmonella enterica serovar TypMmurium by heat and by different nonthermal treatments. J Food Prot 66 31-37. 

Okubo, M., Inoue, M., Kuroki, T. et al. (2005) NOx reduction after treatment system using nitrogen nonthermal plasma desorption, IEEE Trans. Ind. Appl. 41, 891-9. 

Locke, BR Sato, M Sunka, P Hofifmaim, MR, Chang JS. Electrohydraulic diseharge and nonthermal plasma for water treatment Industrial and Engineering Chemistry Research, 2006 45 (3), 882-905. 

Mediated electrochemical oxidation (MEO) is an ex situ treatment technology that uses electricity, acid, and a metal catalyst to destroy organic wastes at low temperatures and pressures. The proprietary CerOx Corporation MEO configuration uses cerium metal as a catalyst to oxidize organic waste into carbon dioxide and water. The process occurs in an acidic solution, typically nitric acid. The first step involves the generation of an oxidant at the anode, followed by the reduction of water or another chemical species at the cathode. This technology serves as a nonthermal alternative to incineration. 

Nonthermal processes There are a number of chemical treatment methods developed and used for the processing of hazardous chemical waste. These methods are briefly discussed in the next sections. 

Waste may be stabilized or solidified by either thermal or non thermal treatments. Thermal treatments are ideal for destmction of organic contaminants. They reduce the volume of the waste and, hence, disposal costs. They are, however, energy intensive and more expensive than nonthermal methods, and release volatile elements that need to be contained. If the waste stream contains inorganic contaminants, the residue left after the thermal treatment is often more concentrated in these contaminants because they cannot be destroyed by such treatment. They also contaminate equipment such as furnaces and filters used during the treatment, which also ultimately need proper disposal. Thus, there is... 

Scientific studies have found that the differences between microwave and conventional pyrolysis go beyond the obvious difference in the source of heat. Other differences arise from the very high rates of heat transfer from the microwave-absorbent to the waste, the amount heat received by the primary pyrolytic products once they leave the absorbent bed and the highly reducing environment. These three aspects have been shown to have an important effect in the final products since they modify the extent of secondary and tertiary reactions. Moreover, the scientific studies have shown that a nonthermal microwave effect in these processes is unlikely to exist. Tests have showed the potential of the microwave-induced pyrolysis process for the treatment of real plastic-containing wastes and it is believed that a commercial process could be developed, for example, to recover clean aluminium from plastic/aluminium laminates. Other materials, in particular tyres, coal and medical wastes are very good candidates to be treated/recycled using microwave pyrolysis and there have been a considerable number patents filed with this goal in mind. 

Although it has not been compared directly with verteporfin, rostaporfin appears to have the same potential for management of choroidal neovascularization. Fifteen minutes after intravenous infusion, a red nonthermal diode laser source (664 nm) is used to activate the drug. The phase III trial compared rostaporfin with placebo in over 900 patients with vision between 20/500 and 20/40 and determined that patients treated with rostaporfin 0.5 mg/kg had stable vision compared with placebo recipients (65.6% vs. 39.3%). Patients with vision better than 20/200 and study-compliant lesion size likewise had significantly higher rates of stable vision compared with placebo (63.2% vs. 25%). A smaller subset of patients with predominantly occult CNV detrived a treatment benefit relative to placebo for patients losing less than 15 letters of acuity (63.6% vs. 29.4%). 

Linton et al. (2008) demonstrated the potential of high pressure (SOOMPa, lOmin) for treatment of raw milk to be nsed in the mannfacture of soft cheeses. High-pressnre treatment significantly rednced the level of L. monocytogenes in raw milk and so allowed production of safer nonthermally processed camembert-type soft cheese. 

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