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Journal of Engineering Research

Journal of Engineering Research

Abstract

Increased use of available water resources necessitates the reuse of treated wastewater at least for irrigation purposes. Generally, pathogenic microorganisms are present in treated wastewater; these pathogens are responsible for spread of many infectious diseases. Disinfection stands out as the pivotal stage in the treatment of effluents during wastewater reuse, crucial for averting the transmission of infectious diseases However, disinfection of wastewater with chlorine may form toxic by-products, a number of which are mutagenic and/or carcinogenic. The aim of present study was to examine the possibility of using three processes, namely; ozonation, UV-radiation, and electrochemical process for disinfection of secondary effluent to be use for irrigation purposes. Same contact time of 30 minutes for inactivation of studied microorganisms was provided. Results of investigation indicated that ozonation with residual chlorine of 0.20-0.45 mg/l reduce the fecal coliform, Clostridium perfringens and coliphage up to 99.5, 78.1 and 83.2% respectively. Application of UV-radiation (dose 30 mW/cm2) reduces studied microorganisms up to 99.3, 82.2, and 89.6% respectively. Electrochemical disinfection process (with current density of 1.2 A/dm2) reduces the studied microorganisms up to 99.5, 99.1, and 96.2% respectively. Study revealed that Clostridium perfringens is relatively insensitive to ozonation and UV-radiation. However, both Clostridium perfringens and coliphage responded to electrochemical disinfection process and their counts reduced significantly. Though increase in current density from of 1.2 to of 2.4 A/dm2 did not improve the process efficiency significantly. Results show that UV-radiation and electrochemical processes could be used for disinfecting secondary effluent to obtain a quality suitable for irrigation purposes.

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