Environmental Engineering Reference
In-Depth Information
revealed that organism detection technologies that enable both an indicative and
detailed inspection of ballast water samples are already available today. This con-
clusion was also supported by our tests conducted on board of commercial vessels
to evaluate the suitability of such technologies for practical work by PSC. In sum-
mary, for an indicative sample analysis, it is recommended to use Pulse-Amplitude
Modulated (PAM) fl uorometry to check for viable phytoplankton, use enzyme-
chemistry for bacteria analysis and a stereomicroscope for the analysis of the
zooplankton organisms above 50
m in minimum dimension. It should be noted that
the PAM method does not deliver organism counts, but it gives a semi-quantitative
measurement so that the higher the reading of the instruments is, the higher is the viable
biological content. Enzyme-chemistry for bacteria gives a presence/absence indication,
but cannot evaluate colony forming units as required by the D-2 standard. However,
the presence or absence of the indicator microbes are to be taken as an indication
that the BWM method used was successful or not.
The instruments for indicative analysis referred to above are portable and, with
the exception of the microscope, of hand-held design and deliver results possibly in
less than 10 min so that PSC could check for compliance already on board of the
inspected vessels. However, a certain training level is needed to use these organism
detection tools that a PSC offi cer can operate the tools.
For a detailed sample analysis, the recommended methods are more cumbersome
and include fl ow-cytometry and epifl uorescence microscopy for the analysis of
phytoplankton, with a viability test using stains. Zooplankton should be analysed by
a microscope either using gentle poking or a stain to check the organism viability.
For bacteria analysis it is recommended to use selective media and it seems that an
incubation time of at least 48 h is needed to proof compliance with the D-2 standard
so that these results may only become available when the vessel has already left
the port. In these cases PSC may keep record of such a vessel for a future inspection
of the vessel should she call for this port again or notify the next port of call.
The sample processing methods for a detailed analysis are not portable and require
a high experience level of a trained biologist so that the samples either need to be
brought to a laboratory for subsequent analysis or a van may be equipped with
these methods and driven to the port for a sample analysis on the pier.
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Final Conclusions
Noting the problems caused by unmanaged ballast water movements naval architects
considered to design vessels which would not require the use of water as ballast.
Other attempts to solve the problem included a vessel design with continuous fl ow
through of ballast water. However, all alternative ballast concepts so far did not
reach a commercially viable level so that the use of ballast water in segregated ballast
tanks and/or in cargo holds seems to be the only practicable ballast method today.
In the absence of the globally applicable BWM requirements of the BWM
Convention, some countries and regions require BWM already today. Most of these
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