Biotesting – the modern criterion of evaluating the efficiency of UV-systems for water disinfection

Summary

Nowadays ultraviolet irradiation increasingly becomes an actual method of water disinfection. Herewith units with amalgam and mercury low pressure lamps are mostly used. In the radiation spectrum of these lamps the mercury resonance line is dominating with 253.7 nm wave length on which up to 40% of the lamp power can fall. Radiation with this wave length has a powerful disinfection effect. The impact of UV-irradiation results in irreversible DNA and RNA damage in microorganisms so that the latter lose their reproductive capacity (become inactivated). The main parameter that characterizes the efficiency of these installations is UV-irradiation dose. It is a calculated value, therefore to obtain the maximum information on the operation of a UV-disinfection unit it is advisable to carry out biotesting with the help of live microorganisms. Besides, in some countries (Germany, France, Austria, USA) biotesting of UV-systems is obligatory. In Russia bio-validation is not obligatory; therefore real biological tests are often substituted with computer simulation. Process simulation carried out for a seven-lamp unit manufactured by «LIT» Scientific-Production Association produces the results close to the results obtained during biotesting. This confirms the range of use of disinfection UV-unit claimed by the manufacturer. However, the absolute guarantee of the UV-unit efficiency is bio-validation only since it supposes the use of live water and microorganisms. The data obtained in the process of biotesting allow describing the specific features of the disinfection unit operation to the fullest extent possible. The certificate verifying biotesting is a credible guarantee that the unit will provide for the required level of water disinfection.

Key words

microorganisms , inactivation , biotesting , amalgam lamp , ultraviolet irradiation , UV disinfection , UV-unit , irradiation dose

Efficiency and economic expediency of the industrial methods for wastewater disinfection

Summary

Technical and economic assessment of municipal and industrial wastewater disinfection methods is given. At present the method of UV-disinfection with the use of low pressure amalgam lamps is recognized from both technical and economic points of view as a most acceptable method widely used all around the world. UV disinfection ensures most efficient inactivation of pathogenic microorganisms including chlorine-tolerant (viruses) present in effluents. UV irradiation of wastewater is not accompanied with formation of by-products that could produce negative impact on living organisms and human health, i. e. this method is both environmentally and hygienically safe.

Key words

chlorination , ozonization , disinfection , ultraviolet , wastewater , toxicity , amalgam lamp