Enhancing Disinfection of Contaminated Natural Water Using 40 kHz Frequency Cavitational Reactor

Abstract

Natural water quality is continuously diminishing with human intervention and poses a major threat to the ecosystem. The present work investigated the treatment of contaminated lake water using a 40 kHz frequency cavitational reactor. The total colony count present in raw water was 1,300 ± 150 CFU with initial chemical oxygen demand (COD) of 100 ± 30 mg/L. The synergy of cavitation with a catalyst (titanium dioxide [TiO2]) and ozonation was studied. The comparative performance was analyzed by comparing individual and synergic effects. The combined effects of a catalyst with cavitation have shown the maximum removal of the microbial count and COD. Techno-economic feasibility analysis confirmed that the synergy of a catalyst with cavitation results in the maximum reduction in microbial count and COD. The percentage removal of coliform such as Enterobacter, Salmonella, and Escherichia coli (catalyst concentration: 25.0 μM/L and treatment time: 20 min) was 90.8, 92.6, and 100, respectively, with COD removal of 71.6%. Enhanced results may be obtained due to an increase in the cavitational effect in the presence of a solid catalyst. The synergy of cavitation with TiO2 enhanced the microbial removal rate by 45.8% compared to the individual effect. Investigation confirms that synergy effects produced from ultrasound and catalyst were highly beneficial for reducing microbial count from raw water with a substantial COD reduction.