Disinfectant considerations

Solar heating, which can result in a 7-log reduction in viable bacteria over 6 hours, is a possible disinfection consideration for developing countries. 

Several methods have received considerable research attention as alternatives to salt curing. These include use of sodium bisulfite as a disinfectant to allow preservation with or without decreased salt in a brine cure use of disinfectants such as quatenary amines for temporary preservation in direct shipping to the taimery from the packing plant (see Disinfectants and antiseptics) preservation of hides by radiation sterilization (see Sterilization techniques) and substitution of materials such as potassium chloride for sodium chloride. These methods have found only limited commercial success. 

Eggers H.J. (1990) Experiments on antiviral activity of hand disinfectants. Some theoretical and practical considerations. ZentralblattBakt, 273, 36-51. 

Considerable research has been done in many industrial countries, especially in Japan and in the former U.S.S.R., on the radiation treatment of waste water and other liquid wastes (see Pikaev and Shubin, 1984 Sakumoto and Miyata, 1984). Apart from disinfection or sterilization, the processes involve the radiation treatment of polluted water, the radiation-induced decomposition of dyes, phenols, cyanides, and so forth, (vide supra). At the basis of purification of aqueous waste... 

Testing separately samples using both methods at 100°C learns that that the velocity of the processes increases considerably and the time for treatment is shortened but the values of physicomechanical properties are reduced with 8-9%. That is a reason to consider that optimal conditions for treatment using both methods are 80°C during 50 minutes. These conditions could be created and maintained in means for decontamination and disinfection of devices and armament. 

A considerable amount of o-cresol is consumed directly as either a solvent or disinfectant. o-Cresol is also used as a chemical intermediate for a wide variety of products. o-Cresol is hydrogenated to... 

Other Important Considerations with Membranes Oxidizers such as sodium hypochlorite (i.e., CIO2), bromine, iodine, and ozone, which are typically used in the disinfection of wastewater, are not well tolerated by thin-hlm membranes. Such disinfectants can thus influence the efficacy of membranes in removing contaminants such as PPCPs. Furthermore, membranes can become fouled by microorganisms that can metabolize the membrane material. Thus, microbial counts of >100 cells/mL can be problematic. Likewise, dead-cell debris can also cause fouling. Membranes can also be fouled by heavy metals such as chromium. Thus, if heavy metals are deemed a problem, they should be precipitated from the wastewater prior to the filtration with membranes. 

Bromate has been classified as a human carcinogen by both the I/VRC (International Agency for the Research on Cancer) and the USEPA (United States Environmental Protection Agency) and is known to be toxic to fish and other aquatic life [11, 12]. Bromate could be produced in aquatic systems upon the oxidation of aqueous bromide. Controlled ozonation has been considered as an effective disinfectant tool in aquatic systems [13] but when sea water is subjected to ozonation, oxy-bromide ozonation by-products (OBP) are produced and these are important both in terms of their disinfection ability and also in relation to their potential toxicity. When seawater is oxidized, aqueous bromide (Br-) is initially converted to hypobro-mite (OBr ) which can then either be reduced back to bromide or oxidized further to bromate (Br03-) which is known to be toxic to fish and other aquatic life and classified as a human carcinogen. There has been thus a considerable interest in bromate analysis so that trace analysis of bromate in water has received considerable attention in recent years. 

Phage preparations have also been found to be very useful in the disinfection of surfaces and facilities in hospitals. Walls in wards, different surfaces, and even instruments and wounds (the source of some pathogens) have also been treated, with a considerable effect in children s clinics [41], Recent studies demonstrated a high eradicating effect of P. aeruginosa and S. aureus phages in a laboratory environmental model [42, 43]. 

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... 

Considerable information of a general nature is available for uncontaminated water subject to the production of disinfection byproducts. The mutagens produced by drinking water chlorination appear to be numerous, but they exist either at low levels or are of low potency. For both the unresolved mixtures and for the few mutagenic compounds thus far identified, activity is readily reduced or destroyed by treatment with alkali or 4-nitrothiophenol and may be removed by GAC treatment. From water sources subject both to mutagen formation via disinfection and to periodic contamination by toxic chemicals, experimental full-scale GAC treatment systems have provided mutagen-free water. 

This situation provided the opportunity for the decision maker to consider many other factors when the control decision was made. The predominant factors driving the control decision were judgmental and unquantifiable. They included the essentiality of the disinfection process in the control of waterborne disease (which is a large risk), the desire to optimize drinking water quality so as to avoid unnecessary risks, and the consideration of the unique compliance problems of small underfinanced and marginally operated water systems. Ultimately, the decision was driven by the feasibility and costs of treatment process improvements. 

In the control of chlorine disinfectant systems, the effective use of the chlorine for its intended purpose is assumed if the treated water considerably downstream from the chlorinalor contains a residual of chlorine. Depending upon use. lull-contact tinte may be assumed alter len miuules. or the interval may be extended lo several hnurs. The systems also are usually carefully monitored by bacteriological testing. Normally a dose of I lo 2 milligrams of chlorine per liter is adequate lo destroy all bacteria and leave an effective residual. Residuals of 0.1 to 0.2 milligrams per liter are usually maintained in the diluent streams front water-treatment plants as a factor of safely for consumers. 

Ellis KV (1991) Water disinfection a review with some consideration of the requirements of the third world. Crit Rev Env Contr 20 341-407... 

---