Effects of ballast water (BW) treatment by Advanced Electro-Catalysis Oxidation Processes (AEOP) on abundance, activity, and diversity of marine bacteria were examined in a full-scale ballast water management system (BWMS) at Yangshan Port, Shanghai, China. Water samples were collected immediately after treatment and at discharge to evaluate the contingency treatment performance of the BWMS for bacteria. After treatment, the total viable count reduced to 0.7 × 104 CFU·mL−1, and both E. coli and enterococci decreased to 10 CFU·100 mL−1, satisfied the D-2 Standard of the International Maritime Organization (IMO). AEOP can be as an effective contingency reception facility. Sequencing of 16S rRNA gene amplicons demonstrated the declining trend in bacterial diversity, while the treatment did not completely eliminate the risk of bacterial dispersal, including potentially pathogenic bacteria, survived in treated and discharged samples. Bacterial diversity is of greater concern when evaluating effects of ballast water treatment on microorganisms, because the bacteria which can develop adaptive mechanisms to environmental change will have a greater potential for invasion in the new environment.


  • Using high- throughput sequencing based on V4-V5 region of 16S rRNA genes.

  • AEOP can be considered as an effective ballast port contingency reception equipment.

  • The treatment can not completely eliminate the risk of pathogen spread.

  • Bacteria that develop adaptive mechanisms have a greater potential for invasion.

  • Diversity is better than density of bacteria in indicating effects of treatment.

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