Date of Award

8-10-2005

Degree Type

Dissertation

Degree Name

Ph.D.

Degree Program

Engineering and Applied Science

Department

Civil and Environmental Engineering

Major Professor

La Motta, Enrique

Second Advisor

Faschan, Adam

Third Advisor

Kura, Bhaskar

Fourth Advisor

McCorquodale, J. Alex

Fifth Advisor

Stoessel, Ronald

Abstract

This research evaluated and demonstrated the disinfection efficiency of an electrochemical system for total coliform removal from wastewater effluents after secondary treatment. Four bench scale batch electrochemical cells were assembled and operated in the laboratory: the first electro-disinfection reactor was set with aluminum electrodes, the second with standard 316 stainless steel electrodes, the third one with titanium electrodes, and the fourth one with a standard 316 stainless steel cathode and a titanium anode. During the electro-disinfection process the water sample was placed on the reactor/disinfector to which direct current (DC) was charged. The results showed that total coliform counts in the treated water decreased significantly and that the characteristics of the effluent were highly improved, especially when stainless steel or titanium electrodes were employed. A bactericidal efficiency of 98.7 % or higher was achieved within a contact time of less than 15 min and a current density lower than 7.5 mA/cm2 when stainless steel electrodes were used, and a contact time of less than 5 min and a current density lower than 3.5 mA/cm2 when the stainless steel/titanium cell was utilized. Electrochlorination does not seem to be the predominant disinfective means of the process. Production of other short lived and more powerful killing substances such as H2O2, [O], •OH, and •HO2 provide the strong disinfecting action of the system within a short contact time. The bactericidal efficiency of the process generally increased with the current density and contact time, and the impact of these factors was much larger than that of salinity. The results obtained suggest that this electrochemical treatment is applicable to wastewater effluents. However, further investigation on the optimum operating conditions and a detailed comparative study of energy consumption by the electrochemical treatment system and the conventional methods are needed before constructing an industrial application system in the future. It is also indispensable to find out if halogenated hydrocarbons and other toxic compounds are produced during the process.

Rights

The University of New Orleans and its agents retain the non-exclusive license to archive and make accessible this dissertation or thesis in whole or in part in all forms of media, now or hereafter known. The author retains all other ownership rights to the copyright of the thesis or dissertation.

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