Inactivation of pathogenic microorganisms under UV/O3 advanced disinfection system in mariculture water

Abstract

The damage that pathogenic microorganisms cause to mariculture has received a lot of attention lately. Streptococcus agalactiae (S.agalactiae), Escherichia coli (E. coli) and Uronema marinum (U. marinum) are typical harmful microorganisms. This study investigated the inactivation of S.agalactiae, E. coli and U. marinum under UV/O3 system. Results showed that the UV/O3 system could produce hydroxyl radicals (·OH) with strong oxidizing properties, which made the inactivation rate of S.agalactiae reaching 4.31 log in 120 s, the inactivation rate of E. coli reaching 3.1 log in 90 s, significantly more effective than single UV or O3 disinfection system. The efficiency of inactivation will be enhanced by an increase in O3 content and UV intensity. And there was an optimal O3 concentration during the inactivation process. In alkaline and high salinity environment, the inactivation efficiency was greater. Through the detection of chromosomal DNA of S. agalactiae, E. coli and U. marinum before and after inactivation, it demonstrated that the UV/O3 system destroyed the genetic material in the nucleus. The analysis of K+ showed that the system destroyed its physiological function. The non-toxicity of the inactivation approach was demonstrated by the toxicity tests. From the SEM images, it could be seen that the UV/O3 system had an effect on the morphology and structural of bacteria.