Disinfection of swro feed water using low amperage direct current

Abstract

Conventional water disinfection methods could lead to numerous disadvantages with regard to safety and maintenance in addition to the generation of unwanted harmful byproducts. Innovative alternative methods, like the employment of low amperage direct electric current is a cost effective technique that can contribute to similar disinfection results with easier maintenance and no release of hazardous byproducts. The present study focuses on the bactericidal effect of low amperage (0.1–1.0A) direct electric current on six different bacteria types when applied for short periods of time (5–30s). The impact of different parameters on the inactivation process is investigated. These parameters include: the distance between electrodes (5, 10, 15cm), pH of seawater (6, 8, 10) and operating temperature (10, 20, 30°C). The main objective of this study is to attribute the inactivation phenomenon exclusively to the impact of current rather than to the mutual effect of both electric current and chlorine generated by seawater electrolysis. The study outputs confirm that reaching 100% bacterial inactivation is possible. All four parameters: current intensities, application times, bacteria type and electrodes separation distances, have an effect on the inactivation rates. Moreover, the results show that for a specific inspected value of pH (6, 8 and 10) and temperature (10, 20 and 30), no significant influence on the inactivation process is detected. The mechanism through which the bacterial inactivation occurs could be explained by cell wall damage of the treated bacteria, as revealed by SEM. Low intensity electric current was found to be feasible for the disinfection of seawater inoculated with raw sewage and should be tested for the disinfection of other types of water like: Brackish water, surface water and groundwater.