Disinfection for water system using new electrolytic system

Abstract

The land area of Hong Kong is 1104 km² and the population reaches nearly 7 million. Severe environmental problems raised up because of concentrated economic activities, population growth, and lack of pollution control. In this paper, a theoretical basis and practical evidence for the application of new electrolytic system on the water treatment are provided. These experimental results are expected to be helpful for the process design of water treatment system and reduction of the water pollution. This thesis compiles the works carried out to develop a RuO₂ electrolytic and TiO₂ photocatalytic system for water disinfection system. A RuO₂ electrolytic and TiO₂ photocatalytic integrated water disinfection system was developed to disinfect swimming pool water, fountain water and flashing water. This relatively compact system enables water disinfection without having to resort to conventional chlorine dosing, which is costly and poses potential health hazards to the public. The electrolytically generated free chlorine could achieve a stable 1-3 mg/L residual level that could effectively produce a bacterial reduction which was equivalent to more than 99 % bacterial removal as required by local legislation. These results, when translated into absolute figures for specific pathogenic bacteria, represented an extremely promising 99.9 % of Escherichia coli and a 100 % Cholera vibrio removal. Furthermore, a stable 100 % pathogenic destruction was achieved at a relatively short treatment time of 60 minutes and relatively low operational electro-potential of 30 volts. The pilot-scale system was installed, monitored and assessed on a long-term basis at Harbour Place, Hung Hom. The technology for water treatment was tested on-site rigorously in order to demonstrate its stable treatment performances, long-term reliabilities and maintenance requirements. The Ruthenium Dioxide coated electrolytic disinfection system has been very effective in treating and disinfecting water in water features in residential estates. The effectiveness and stability of electrolytic disinfection mechanism and process have been optimized. The system will also be tested and proven in treating saline water, domestic and commercial toilet flushing water to remove the pathogens.