TEXTE Environmental Impacts of Exhaust Gas Cleaning Systems for Reduction of SOx on Ships — Analysis of status quo
Report compiled within the framework of the project ImpEx
Identification of a correlation between the PAHyne parallel on-board measurements
with the laboratory results for PAHzpa16 and oil content (hydrocarbon oil index, HOT)
in the OL discharge water samples. The dataset, however, is insufficient to conduct
any robust statistical analyses. Thus further investigations are required. No
correlation was found with the on-board monitoring data.
The study reports, among several limitations during the sampling campaign, missing sampling
points or unsuitable design (material and piping size) of sampling points. The issues found with
the on-line monitoring systems are stressed in that research work and will be further examined
in the present project (AP 2.2).
An important part of this research study is the dispersion modelling based on the results of the
chemical characterization (see chapter 7.3). Additionally, water samples from the sampling
campaign were provided to the German Federal Institute for Hydrology (BfG) to conduct a
separate study about ecotoxicological effects of EGCS discharge (see Kathmann et al. (2020) in
chapter 7.2).
Carnival Corp. & plc and DNV GL (2019) (in Table A-4 presented as CCL) carried out a study,
where Carnival Corporation was responsible for the organization of the sampling campaign and
DNV GL for the compilation, review and analysis of the laboratory results. In this project, 53
ships operating with OL systems were sampled. Since a detailed project report is not available
(only a presentation), not all details of this database are known, e.g. information about the ships,
EGCS systems and sampling conditions. In a follow-up project (Faber et al., 2019), it is
mentioned that the samples were collected from cruise ships, bulk carriers and ferries being in
service in different locations in the Caribbean, the eastern Pacific, the Tasman Sea, the Strait of
Malacca, the Atlantic Ocean, the North Sea and the Baltic region. The results presented in Table
A-4 correspond to the average values excluding statistical outliers more than three standard
deviations from the mean in the sampling point prior to any dilution (here called “Gross post-
EGCS”). Besides the values shown in Table A-4, the scope of the parameters included others such
as hydrocarbons (C10-Ca40), suspended solids, pH, BOD, COD and chromium VI, but their results
are not reported. The enrichment of the pollutants in the seawater was calculated (“Net post-
EGCS” = “Gross post-EGCS” - inlet). These values were compared to the current IMO
requirements, wastewater land-based point standards (German Wastewater Ordinance and EU
Industrial Emissions Directive) and stricter quality standards (EU Water Framework Directive
and WHO Drinking Water Guidelines). The authors concluded:
Phenanthrene and sum of PAHgpa16 average gross post-EGCS concentrations were far
Jelow the IMO limit value for PAHypne. The same was observed for nitrate
concentrations.
Concentrations of the tested (and possible to compare) parameters in all samples
were below the wastewater land-based point standards.
Net post-EGCS average concentrations (excluding statistical outliers) of the tested
(and possible to compare) parameters were below the stricter quality standards.
When reviewing the net post-EGCS metal concentration values, only for chromium, copper,
nickel, vanadium and zinc an enrichment is clearly noticed. The aim of this work was to gain
information about the EGCS discharge water quality and the presence of pollutants. However, as
commented above, there is a related research project using the resulted database to conduct a
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