Disinfection treatment methods

In some instances, provisional guideline values have been set for constiments for which there is some evidence of a potential hazard but where the available information on health effects is limited. Provisional guideline values have also been set for substances for which the calculated guideline value would be below the practical quantification level, or below the level that can be achieved through practical treatment methods, as well as for certain substances when it is likely that guideline values will be exceeded as a result of disinfection procedures. 

The practical use of solar disinfection in drinking water was first studied by Acra et al., who filled polyethylene bags with water before exposing them to full sunlight. Recently, a review of solar disinfection used as a water treatment method has been published (Reed 2004). 

Equipment Method of treatment Sterilization or disinfection Preferred method Comments... 

When there is less control over raw water quality, such as when the supply is downstream of several towns already using a river, or when the natural supply from a groundwater source is poor, more complicated treatment methods are required (e.g.. Fig. 5.1). Following the preliminary treatment steps outlined in the following paragraphs, filtration plus chlorination, or chlorination alone can be used to disinfect the finished supply. When filtration is not used to supplement disinfection, the U.S. EPA recommends that two different disinfection methods be used to ensure supply safety, (e.g., uv irradiation and chlorination). 

Certain waste treatments reduce multiple hazards in one step. For example, incineration can destroy oxidizable organic chemicals and infectious agents, waste feed rates can be controlled to meet emission limits for volatile radionuclides, and radioactive ash can be disposed of as a dry radioactive waste. Likewise, some chemical treatment methods (e.g., those using bleach) both oxidize toxic chemicals and disinfect biological hazards. Such treatment could convert a chemical-radioactive-biological waste to a radioactive waste. 

Phenols The term phenols is used to designate a series of hydroxyl derivatives of benzene, with phenol as the parent compound. These compounds come from paper mills and cellulose factories as well as from degradation of pesticides such as carbaryl. Disinfecting treatments of chlorine-containing waters produce chlorophenols, which cause a persistent taste. Analytical control of these compounds is commonly performed by chromatographic or photometric methods. 

Following biological treatment and clarification, treatment plants disinfect the water and many discharge it to surface water. Some treatment plants use advanced treatment methods in addition to the unit operations described here, and it is possible that some advanced treatment methods may remove microbeads [139]. 

Nanotechnology can usher in a revolution in the domains of water treatment and distributed water reuse. It is capable of precluding concerns related to the formation of harmful disinfection by products associated with conventional water treatment methods. Nanomaterials are endowed with unique properties like high surface to... 

Water treatment method that uses ozone as an oxidant to remove pollutants, i.e., chemical pollutants present in small concentrations that are difficult to remove, or to disinfect water. 

In all antiseptic testing, it is recognized that skin and mucous membranes to which products ate appHed cannot be disinfected or sterilized but it is possible to significantly reduce the population of transient and resident pathogenic bacterial flora. AH in vivo test methods requite a deterrnination of the bacteria on the skin before and after treatment. Because of the normal variation in bacterial population of the skin of different people, a number of people must be tested in order to make a statistical analysis of the results. Different parts of the body are used for different tests. In aH of the tests the details of the protocol ate extremely important and must be strictly adhered to in order to obtain reproducible results. 

Treatment of a water supply is a safety factor, not a corrective measure. There are a number of ways of purifying water. In evaluating the methods of treatment available, the following points regarding water disinfectants should be eonsidered ... 

Boiling - This involves bringing the water to its boiling point in a container over heat. The water must be maintained at this temperature 15 to 20 minutes. This will disinfect the water. Boiling water is an effective method of treatment because no important waterborne diseases are caused by heat-resisting organisms. 

In one procedure that has been widely used, the sample, after suitable treatment, is refluxed with sodium and isopropyl alcohol, after which the solution is diluted with water and the inorganic chloride is determined by standard methods (13, 54) The method has been adopted by the Association of Official Agricultural Chemists 29, 30) as a tentative one for technical DDT and for dusts, oil solutions, and aqueous emulsions of DDT, for use in the absence of other chlorine-containing compounds. The National Association of Insecticide and Disinfectant Manufacturers has also accepted the total-chlorine method for the analysis of these preparations 28). Essentially the same procedures have been described by Donovan 22), of the Insecticide Division of the Production and Marketing Administration, for technical DDT and various commercial DDT products containing no other compounds interfering with the chlorine determination. 

The above two studies with actual contaminated water (possibly containing a wide range of bacteria/microorganisms) confirm the suitability of the hydrodynamic cavitation phenomena for microbial disinfection. Cost of the treatment is another important factor, which needs to be ascertained, before cavitation can be recommended as a replacement technique for the conventional methods of... 

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