Water pollution disinfectants

Aieta EM, Berg JD, Roberts PV, et al. 1980. Comparison of chlorine dioxide and chlorine in wastewater disinfection. J Water Pollut Control Fed 52(4) 810-824. 

Gerba, C. P., Wallis, C., and Melnick, J. L. (1977b). Disinfection of waste water by photodynamic action. J. Water Pollut. Control Fed. 49,575-583. 

Oliver BG, Carey JH (1976) Ultraviolet Disinfection an Alternative to Chlorination, / Water Pollut. Contr. Fed. 48, No. 11 2619-2624. 

WPCF, Wastewater Disinfection. Manual of Practice FD-10, Water Pollution Control Federation, Alexandria, VA, 1986. 

Volatile Organic Compounds (VOCs) constitute a very important class of water pollutants because of their persistence in addition, many of them are suspected of being carcinogenic. There are about 60 VOCs, including benzene, toluene, ethylbenzene, and xylenes ( BTEX compounds ), halomethanes, and haloethanes. The presence of some of them in water is due to anthropic activities, for example, the use of chlorinated solvents in industries and laundries, and the formation of halomethanes as by-products of water disinfectants. With respect to Italian law DL 31/01, the maximum allowable concentration (threshold) for the sum of trichloroethylene and tetrachloroethylene concentrations in drinking water is 10 ppb, whereas the minimum account for the sum of a set of four halogenated compounds, namely chloroform, bromoform, bromodichloromethane, and chlorodibromomethane must be as low as possible and must not exceed 30 ppb. Note that 30 ppb is equivalent to 30 Tg L-i. 

A major problem with the use of chlorine as a disinfection agent is by-product production from the reaction of chlorine or bromine generated from chlorine with organics in water. The most common such by-products are the trihalomethanes including chloroform, HCCI3, and dibromochlo-romethane, HCBr2Cl, noted as water pollutants in Chapter 4, Section 4.13. Humic substances are common precursors to chlorinated by-products their removal before water chlorination prevents the formation of organochlorine by-products. 

Ceramic membranes impregnated with crosslinked silylated CD polymers, i.e. organic-inorganic filters were investigated for removal of some organic pollutants from water [59]. It was established that they remove polycyclic aromatic hydrocarbons PAH, the monocyclic aromatic hydrocarbons, trihalo methanes, methyl-f-butyl ether and pesticides. Trihalomethanes are disinfection by-products, they (especially dibromochloromethane) increase the risk of cancer. The pesticides simazine and atrazine are drinking water pollutants. 

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. 

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). 

Water can usually be used as an ingredient, a solvent, and a principal agent for cleaning and disinfection in plants or transportation systems for delivering raw materials. Since water consumption will always be a part of the food processing industry, it has become the key target for pollution prevention and source reduction practices. 

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... 

Waste water from a drain or rain-overflow usually contains sediment, including sand, dust and solid particles such as grit. But smaller, colloidal particles also pollute the water. Water purification requires the removal of such particulate matter, generally before disinfecting the water and subsequent removal of any water-soluble effluent. 

An adequate supply of clean, potable WATER is one of the primary requirements for good health. Traditionally, health hazards associated with water have been the classic waterborne diseases, namely, typhoid, cholera, and hepatitis. The advent, advancement, and practice of the science of bacteriology after the late 18th century led to the recognition of the causes and sources of these diseases, which resulted in the development of disinfection processes and in the recognition of the necessity to prevent public potable water sources from pollution from sewage and postdisinfection contamination. 

Ozone is used in the treatment of drinking water and in industries where high purity water is required (e.g., breweries, pharmaceuticals, and electronics). Ozone is also used in industrial wastewater pollution control, wastewater disinfection, and odor control in the treatment of process water, such as cooling tower water in the treatment of swimming pools and spas in pulp bleaching and in organic synthesis, as a selective oxidant. 

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