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The Biological Basis for Ballast Water Performance Standards: "Viable/Non-Viable" or "Live/Dead"?
Ernest R Blatchley Iii1, John J Cullen2, Brian Petri3
1Lyles School of Civil Engineering and Division of Environmental & Ecological Engineering , Purdue University , 550 Stadium Mall Drive , West Lafayette , Indiana 47907 , United States.
Environmental Science & Technology
|June 22, 2018
Summary
Ballast water management regulations require effective species detection. The most probable number (MPN) assay is recommended over vital stains like FDA/CMFDA for evaluating UV treatment efficacy in preventing aquatic invasive species transfer.
Area of Science:
- Marine biology
- Environmental science
- Microbiology
Background:
- Shipping facilitates global commerce but risks invasive species transfer via ballast water.
- International Maritime Organization (IMO) and USCG regulations aim to mitigate this risk.
- Discharge standards are identical, but assay definitions for treatment effectiveness differ.
Purpose of the Study:
- To compare biological assays for quantifying ballast water treatment effectiveness.
- To evaluate the suitability of different assays for Type Approval testing.
- To determine the most appropriate assay for UV-based ballast water treatment.
Main Methods:
- Review of available assays: FDA/CMFDA vital stains, motility, and MPN.
- Analysis of assay mechanisms and implications for Type Approval.
- Evaluation of assay performance with UV irradiation treatment.
Main Results:
- FDA/CMFDA and MPN methods yield different results, especially for antimicrobial treatments preventing replication.
- UV irradiation effectiveness is accurately assessed by MPN, aligning with treatment objectives.
- FDA, CMFDA, and motility assays have recognized error sources.
Conclusions:
- MPN assay provides a direct measure of growth and reproduction, consistent with ballast water management goals.
- MPN is the recommended standard for Type Approval, particularly for UV-based treatment.
- Development of relevant indicative tests for compliance testing remains a research priority.