Scrubber Washwater Survey (SWS)

Project: Effects of wash water from exhaust gas cleaning systems on the marine environment of seagoing ships

Since 2015, limit values have been in force in the North Sea and Baltic Sea that allow a maximum sulphur content of 0.1% in the fuel of ships (SECAs, Sulphur Emission Control Areas). Alternatively, the use of heavy fuel oils with a sulphur content of more than 0.1% is permissible if ship exhaust gas cleaning systems, so-called scrubbers, are used. This technology uses seawater for flue gas scrubbing. The seawater is enriched with water-soluble and particle-bound pollutants in open-loop systems and then returned to the sea. This pollutes the environment, at least in the vicinity of the ship. With an increasing use of this technology, which is foreseeable, this can also lead to more extensive damage to the environment.

The aim of the project is to improve the evaluation of the use of exhaust gas purification systems on seagoing vessels. If more comprehensive information on the use of this technology is available, European and international regulations will also be adapted and improved.

Interim results (as of January 2018)

A market and data analysis on the use of scrubber technology that has already been prepared will be continued and further developed. From 2020, global sulphur limits of 0.5 % will apply to marine fuels. The adaptation strategies of the shipping companies will be taken into account.

In the first project phase, a sampling and analysis concept was developed for the sampling and analysis of wash water from scrubber systems and completed in 2017. National and international feedback was taken into account. Based on this concept, a total of 5 sampling campaigns were carried out between May and November 2017 on the North Sea and Baltic Sea. Ships of different types of use were used. Both wash water from open-loop and closed-loop circulation systems were sampled.

Overall, extreme differences were found between the washing waters of individual scrubber systems. The consistent applicability of existing international standards to the scrubber washing water analysis must be fundamentally re-examined in parts.

Measures in the project

  • Inventory on the use of ship pollution abatement techniques to reduce sulphur in maritime navigation,
  • Collection of information on the expected quantities of wash water and thus the provision of a basis for the expansion and further development of the technology,
  • Investigations of the washing water for the detailed naming of the contents/pollutant contents,
  • Collection of information for an ecotoxicological assessment of washing waters,
  • Carrying out measurements in the marine environment in order to demonstrate the effects of the use of this technology on the environment,
  • Implementation of (mesoscale) dispersion modelling for the introduction of wash water into the water column in order to improve the assessment of its spatial impact.

The data obtained in the project will be used to advise international bodies. The BSH is involved in these committees together with the BMDV, the BMU and the UBA:

  • Subgroup EGCS (Exhaust Gas Cleaning System),
  • European Sustainable Shipping Forum (ESSF),
  • Marine Environment Protection Committee (MEPC),
  • International Maritime Organization (IMO),
  • Baltic Maritime Environment Protection Commission (HELCOM).

Furthermore, it supports national efforts to implement the Marine Strategy Framework Directive (MSFD) by investigating new pollutant input paths (scrubber wash water).

Current project work

The wash water are currently being investigated for organic pollutants, heavy metals, nutrients and other basic parameters. Since the beginning of 2017, a numerical modelling has been developed to investigate the dispersion and transport behaviour of scrubber wash waters. Currently, the model validation and the elaboration of source concepts and emission scenarios are taking place.

The project is an environmental research plan (UFOPLAN) funded by the Federal Environment Agency (UBA) and is being implemented by the BSH. Within the BSH, the BSH laboratory in Hamburg-Sülldorf and the departments of environmental protection in maritime transport and operational models are involved.