Sterilisation of water

An ingenious apparatus has been designed,3 in which the ultra-violet light, produced simultaneously m the silent discharge employed for preparing ozone, is utilised to assist m the sterilisation of water. The last named is first acted on by the light, the partial sterilisation thus induced being completed immediately after by contact with the ozone. 

Formation of Water—Purification—Storage—Removal of Iron and Algie — Filtration—Hardness—Softening of Hard Waters—Pennutit—Sterilisation of Water—Physical and Chemical Methods... 

Another extensive application is in the sterilisation of water. As early as 1886 experiments were carried out on the c onisation of water to effect the removal of organic matter and bacteria. Eight years previously Pasteur had introduced his germ theory of disease and the danger of transmitting diseases such as typhoid and cholera by vitiated waters was beginning to be realised. In 1885 Percy Frankland had shown that almost all the bacterial content of water... 

Mercury vapour lamps are widely used for a variety of purposes, as for example in the sterilisation of water and the irradiation of milk to produce vitamin D. The use of mercury in making mirrors has largely been superseded by silvering. 

Hypochlorite can be produced by the reaction of chlorine gas with sodium hydroxide solution. On-site generation of hypochlorite avoids storage and transport difficulties associated with chlorine gas, and is convenient for many applications, including sewage treatment, sterilisation of water, disinfection, biological growth prevention and enhanced oxidation of, for example, cyanide wastes. The electrochemical generation of hypochlorite has been the subject of several reviews (see [84]). 

Miscellaneous Applications. PEIs and their derivatives ate used as cementation auxihaties in cmde oil exploration (459), and for breaking cmde oil emulsions (460) in cmde oil extraction. Seed coatings of water-soluble copolymers containing polyethyleneimine have been developed (461). Polyethyleneimine derivatives have positive photoresist properties (462) amidated polyethyleneimines improve the flow properties of cement (463) and with few exceptions, A/-acyla2iddines act as chemical sterilisers for insects (464). 

In addition to these forms of water, several other official aqueous vehicles can be used. These are isotonic injections that can be sterilised, eg, sodium chloride. Ringer s, dextrose, dextrose and sodium chloride, and lactated Ringer s. Addition of water-miscible solvents such as ethanol or propylene glycol increases solubiUty and stabiUty. 

Titanium dioxide has also been involved in the photocatalysis of toxic inorganic substances to yield harmless or less-toxic species. Sterilisation of drinking water by chlorine yields potentially carcinogenic compounds so that ozone has been used as an alternative sterilising agent. Bromate... 

The direct sterilisation of particulafe solid foods in a gas-solid fluidized bed was proposed as long ago as 1968 by Lawrence et al. (1968) who sterilised wheat flour in steam-air mixtures at the pilot scale. However, Jowitt (1977) described an atmospheric pressure process for fhe sferilisation of canned foods in which the cans are immersed in a fluidized bed of inert particles. This has a number of advantages compared to the conventional retorting process using pressurised steam or hot water ... 

Finally, a little chlorine gas is added, which sterilises the water and kills any remaining bacteria. Excess chlorine can be removed by the addition of sulfur dioxide gas. The addition of chlorine gas makes the water more acidic and so appropriate amounts of sodium hydroxide solution are added. Fluoride is sometimes added to water if there is insufficient occurring naturally, as it helps to prevent tooth decay. 

Sterilization. Seeds of each wheat accession were surface-sterilised by soaking in 70% ethanol for 2.5 min, followed by four rinses in sterilised distilled water. They were then soaked in 2.5% sodium hypochlorite solution for 15 min, followed by five rinses in sterilized distilled water. 

Pre-germination. Surface-sterilized seeds of the wheat genotypes were each soaked in sterilized water for imbibition of water in light at 25°C for 24 h and then rinsed with fresh sterilised water. The wheat seeds were then incubated in light at 25°C for another 24 h. 

Sterilisation of blood products and other organ transplant tissues opens another area for photodynamic effect applications. Photodynamic activity of some inorganic sensitizers together with their photocatalytic activity can be very useful in water, air, and surface detoxification (see Chapter 21). APDT can be a new approach for safe food. The reduction of several Gram-positive bacteria and yeasts has been observed in tests with visible light and haematoporphyrin or chlorophylls (natural constituents of food) as photosensitizers [54],... 

By sterilisation is understood the destruction of all organisms4 in the water, whether pathogenic or not. In the absence of suitable mechanical filters or in cases of doubt as to the efficiency of the filters in removing pathogenic germs, sterilisation should be resorted to, for this is the only sure method of preventing the spread of water-borne diseases. 

Ultra-violet light, such as that emitted by a mercury-vapour lamp, exerts a powerful germicidal action on water and ice. In a series of experiments earned out at Marseilles it was observed that a lamp working with 3 amperes at 220 volts destroyed pathogenic organisms in water within a radius of 2 inches in two seconds.2 In order to ensure complete sterilisation m a stream of water, the latter is made to flow, by... 

Chemical Methods of Sterilisation.—Very efficient sterilisation of suspected waters may be effected by chemical methods, and the cost may be materially reduced by first purifying the water as far as may be... 

Calcium peroxide,3 Ca02, and magnesium peroxide Mg02, have also been recommended, the former being sold under the name of bicalzit, whilst an impure form of the latter is used in the sterilisation of bottled mineral waters. 

Chemistry (Theoretical and Applied).—Air. Water. Chemical theory. Acids, alkalies and salts. Carbon and its oxides fuels. Soaps. Textile fabrics. Water softeners. Sugars, starch, alcohol, acetic acid. Proteins. Fats. Yitamines. Yeasts, moulds and bacteria. Study of certain foods. Preservation and sterilisation of food stuffs. The practical work will be partly illustrative of the lectures, and partly experimental craft work, i.e. —... 

This salt is a white, crystalline powder, readily soluble in water, the solution having a neutral reaction. Its water content is variable, commercial samples containing from 8 to 5 molecules of water, although it may be obtained under suitable conditions with 2 and 6 molecules of water. It has been shown that solutions of atoxyl cannot be sterilised without some decomposition taking place. ... 

Diamorphine injection is prepared by dissolving the contents of a sealed container in Water for Injections BP immediately prior to use. The instability of the ester groups precludes sterilisation of the injection by autoclaving. 

A comparison of glutaraldehyde with other non-oxidising biocides has been made [Union Carbide 1991]. Each biocide was added to 10 m/ of sterilised cooling water the pH adjusted to 8.5 and the solutions inoculated with a mixture of P. aeruginosa, E. aerogenes, B. cereus and E. coli. Aliquots were removed at the... 

Radiation sterilisation of microbial-laden water is a possible method of... 

Investigation results have shown that in non-sterilised water the concentration of yperite in a solution quickly increases, reaches a maximum in one day and then decreases to a certain constant level (the end of drop dissolution) corresponding to the equilibrium concentration of yperite. Equilibrium was observed 4-5 days after the beginning of the experiments. Yperite concentrations in the water at equilibrium were 10-30 mg/ml (2-5% of the initial concentration). In deionised water the equilibrium concentration even after a year was about 2%. In sterilised natural water the curved pattern of measured yperite concentration was preserved. However, maximum yperite concentrations in water were approximately three fold higher than in the non-sterilised version. Equilibrium was observed after 6-7 days, in this case the yperite content was observed at the level of 3-6% of the initial content. The increase in yperite s transformation rate during the first period is possibly caused by micro-organism effects. However, final conclusions can be made only after additional studies. It is... 

Current sterilisation processes are generally not well adapted to polymers, except in the cases of water-soluble polymers and colloids, which can be sterilised by filtration in solution. The simplest process is autoclaving with steam at 120 °C for 20 min. This process can be detrimental to devices that include polymers with thermomechanical properties not compatible with the temperature used in the sterilisation process. 

---