The German Seaport of Emden is facing a tough challenge:
Can they treat the environmental legacy pollution in the sediments and provide sufficient depth of water for port operation without spreading polluted materials to other parts of the harbor?
And do this in a climate friendly way and reduce carbon emissions?
During the process the harbor authorities must secure that any existing pollutants under no circumstances will be distributed to other port areas during the process.
This is a pilot project that began in 2020 with the extensive investigation of the actual pollution scenario by legacy contaminants in the harbour and culminated in 2021 in the kickstart of a field test and is still ongoing.
This is the question that the Port of Emden is trying to answer in their DUAL Ports Pilot Project where a promising in Situ pollutant treatment alternative is being investigated in a field experiment in a semi-enclosed section of the harbour.
Laboratory tests give strong indications that it works on a bigger scale.
Pollution from TBT
In parts of the port of Emden, the sediment presents environmental pollutants that entered the harbour mostly due to shipyard activities in the past decades, when several nowadays banned substances were still allowed. Near an old shipyard located at the inner part of the harbour, large quantities of PAHs (polyaromatic hydrocarbons) and TBT (Tributyltin) can be found.
A challenge the Port of Emden is facing is that the recirculation dredging procedures can only be carried out in areas where no pollutants are present in the sediment to be treated.
Any existing pollutants may under no circumstances be distributed to other port areas. This is not ensured by using the recirculation process used in the other parts of the port and therefore the potentially contaminated areas remained so far untouched.
This prevents the use of water depth conservation measures and thus the long-term use of certain parts of the harbour. Therefore, the harbour has seen a target to create an innovative, economically advantageous, and sustainable concept for the removal of pollutants in the port’s sediments, to maintain port operations there in the long term.
Fluid mud
The port is located at the mouth of the River Ems, and this causes problems with large deposits of estuarine sediments in the port. It significantly affects the depth of the port, and it is necessary on an ongoing operation to remove the deposits on the bottom.
This is done by a method where the material, that would otherwise settle, is recirculated, and is turned into a navigable mud layer, also called fluid mud, providing an increased water depth in the harbor.
The adapted trailing suction hopper dredger is used for this. This vessel dredges the very fine sediment into its hold, putting it in contact with the atmospheric air. The constant mixing of the material hinders the settlement and consolidation of it and thus makes it possible to sail through this created fluid mud layer.
A purpose-built vessel constantly sucks up the deposits on the bottom and releases it out again like fluid mud through which the ships in the harbor can navigate.
The process is very simple yet innovative. Normally, sediment on the bounds would be removed completely from the port and sailed away to be dumped either at sea – if not polluted or transported to a land depot. Both methods are expensive and burden the climate with increased carbon emissions.
Sedimentation and thus lower depth are a challenge all ports struggle with.
The Port infrastructure company Niedersachsen Ports has been using the fluid mud method in the port of Emden since 1992 and has good experience with it. Since 2000 the water depth maintenance of the harbour has been done solely by the recirculation process.
The question then is how the port can keep the depth in the areas contaminated with the pollutant TBT from a nearby shipyard without the contaminated mud being spread out in the rest of the port.
“The use of our already established recirculation process not only as a port maintenance method but also as a tool to facilitate the degradation of pollutants is very promising and suitable in our particular case, since we are dealing with organic pollutants in a relatively low to moderate concentration. The TBT will eventually disappear, but it will take a very long time to degrade. We would like to propose a process that stimulates the natural biodegradation of these organic substances, speeding up the degradation process of TBT,” explains Daniela da Rosa, Niedersachsen Ports, Emden.
How is it done?
The degradation of TBT by microorganisms in the environment is a naturally occurring process. Usually, it happens quite slowly because TBT is a man made, persistent substance that is very hard to degrade. A number of methods have been developed over the years for the removal of contaminants from sediments with varying cost ranges, waste generations, energy demands, transport requirements, and so on. Based on the scientific findings regarding contaminants degradation, the processes that take place during the recirculation process may facilitate the natural biodegradation of these compounds and therefore represent an in situ treatment approach worth investigating.
The enrichment of the fluid mud with oxygen from the air can potentially create more favorable conditions for the degrading microorganisms that are present in the system and cause higher microbial degrading activity.
TBT is more quickly transformed into less harmful products thorough the microbial metabolism activity.
The goal of the process is to create improvements of the conditions to optimize naturally occurring processes.
Test area established
A survey was conducted to identify which parts of the harbor that was suitable to conduct a test of the designed process. Area 1 was the least contaminated and other investigated areas were not suitable for the decided process.
Back in September 2021 a “bio-reactor” was set up located at the Oil Harbour (see illustration) to test the process.
“We moved a small part of moderately polluted material from area 1 and brought it into the oil harbour to test the effect of the recirculation process on the TBT degradation rates. The test and the monitoring will run until April 2022. We collect data every second week and analyze this data very thoroughly in order to hopefully be able to evaluate the effectiveness of the process by the end of the project. We have good reason to believe that this method works,” concludes Daniela da Rosa.
The pilot will continue this spring, and port of Emden expects that the outcome will be positive. The goal is to integrate area 1 of the harbor into the regular maintenance schedule to secure nautical depth.
The results of the project regarding the success in the treatment of TBT are still under evaluation and the process can take a longer time in comparison to conventional approaches. In terms of the financial and environmental aspects, however, this is a highly promising approach. The pilot project of Port of Emden is a part of the Dual Ports project, and the preliminary data clearly indicates that the targets in cost and CO2 reduction will be exceeded and that it will improve the economy at the Port of Emden.
“We hope the results of the test will produce meaningful insights for us and that it hopefully will represent the treatment alternative that the port is seeking. We hope to make use of the recirculation process to achieve sustainable decontamination of sediments whilst at the same time to carry on with the more resource efficient port maintenance strategy,” says Daniela da Rosa.
The Pilot project at the Port of Emden supports the overall goals of the Dual Ports project which is 20% operating cost reduction, 20% total cost reduction, and 10% emissions reduction.
According to the calculations carried out by the HWWI the pilot in Emden fulfils all targets by over 90% when the new method is compared with the conventional approach (extraction of the contaminated material, transport to, and depot at a specialized facility).
Contaminated sediments are a major challenge for ports. In some parts of the port of Emden in Germany, the sediment is polluted with environmental pollutants. This prevents the use of water depth preservation measures and thus the long-term use of certain parts of the port. Therefore, the Sediment pilot within DUAL Ports is looking at an innovative and sustainable concept for the removal of pollutants in the sediment, in order to keep the port attractive to customers and maintain port operations there in the long term.
Within this pilot, a pollutant cadastre was developed in 2020, which provided information on the local pollutants. For this purpose, 17 deep boreholes were carried out from which a total of 62 samples were taken and analysed (the project area is in the area of the shipyard sites, see picture). The pollutant register is the basis for the development of innovative approaches within DUAL Ports. The aim is to clean up the sediments as locally as possible and, if necessary, make them usable e.g. in port construction. Students from Leibniz University are also involved in developing approaches together.
One pollutant is to be cleaned locally in a pilot test: TBT (tributyltin) which is an additive from anti-fouling paint degrades when in contact with oxygen. The test is planned for 2021 and is intended to provide information on the extent to which the large-scale degradation by aeration of the sediments is successful.
For more information please contact:
Matthäus Wuckowski, Sustainability Manager at Niedersachsen Ports GmbH & Co. KG
T: +49 170 1644219 | E: mwuckowski@nports.de
In October, the port companies Niedersachsen Ports and Groningen Seaports hosted the workshop Sediment Management in Ports in Eemshaven, Holland. Experts were invited to share their work on issues concerning an efficient management of sediments and the handling of dredging material in ports. The workshops participants had the opportunity to find answers to questions such as what is the impact of current and future sediment movements in the North Sea and the rivers on the sediment entry into ports and what technological developments promise the highest benefit when it comes to warranting safe access to the ports and improve their ecological footprints?
We have collected presentations from the speakers of the workshop Sediment Management in Ports, so you may also have the opportunity to obtain knowledge on the subject.
The nature perspective: Environmental Effects of Sediment Management by Gregor Scheiffarth and Dr. Inga Nordhaus, Lower Saxon Wadden Sea National Park Authority (DE)
Large-scale sediment transport and morphological modeling as a sediment management tool by Dennis Oberrecht, NLWKN (DE)
General Dredging Introduction and Sediment Logistics by Jef De Brabandere, Adjuvans (BE)
Generating Energy by Gasification of Marine Sediments and Waste by Theis von Appen, EXOY Green Systems Gmb H (DE)
Plastix Flux to the Sea and Innovation Trajectories by Eric Toorman (Devriesa, Lisa), Flanders Marine Institute (BE)
Analysis-Methodology of Event-Driven Sedimentation in a Shipyard by Jan Fischer, Ludwig-Franzius-Institute for Hydraulic, Estuarine and Coastal Engineering (DE)
Building with Nature by Martin Baptist, Wagening Marine Research Ecoshape (NL)
Re-use of Sediment in Port or Coastal Infrastructure by Luca Sittoni, Deltares, Ecoshape (NL)
The EU Project DUAL Ports
Niedersachsen Ports has designed this workshop as part of the European project DUAL Ports, which was initiated in 2015. It is funded by the EU and the Interreg North Sea Program. DUAL Ports brings ports, companies, and scientific institutions from Belgium, Germany, the Netherlands, Denmark, and Scotland to the table. The objective of this collaboration is the joint development of solutions and approaches for the long-term reduction of CO2 emissions and pollution caused by the activities of the port industry. The exchange of knowledge between the partners and the resulting synergies are intended to support and accelerate the development and implementation of sustainability innovations in ports.
Further information about the project DUAL Ports is available here: www.northsearegion.eu/dual-ports and www.dualports.eu
The Workshop-Agenda is available here: https://www.nports.de/fileadmin/user_upload/Sediment_Workshop_Eemshaven_Agenda.pdf
“I look at sediment management from a natural perspective. In the projects I am involved with, I look at sediment as a source to create natural values. To create salt marshes and systems that redefine sediment instead of just throwing it out into the sea and wait to see where it ends up. We can use sediment as a resource to recycle – to make something more beautiful of it.”
Martin Baptist is an engineer and marine ecologist at Wageningen Marine Research and working for EcoShape (NL). His interest in the harmonisation of human impacts with natural processes is central in one of his project which researches on the smart use of dredged sediment for the growth of salt marshes.
Salt marshes are very important ecosystems for several reasons:
- They are breeding and resting places for birds
- They are spawning ground for fish
- They reduce wave impact and protect the coast against erosion
- They trap sediment so the coast can grow
- Salt marshes also capture CO2
But the climate changes and the rise of sea level puts salt marshes under pressure. Martin Baptist is part of a project that investigates the right conditions for salt marsh construction and the best possible ways to develop salt marshes in a natural way.
In this project, the Marconi salt marshes, the EcoShape consortium studies morphological and biological conditions in a constructed salt marsh in large-scale experimental plots. Sand was mixed with dredged sediment in various percentages and parts were sown in with Glasswort seedlings. Knowledge obtained in the project helps the development of climate adaptation measures worldwide.
Another project Baptist is involved with is the ‘Mud Motor’. A Mud Motor is a dredged sediment disposal in the form of a semi-continuous source of mud. Natural processes are allowed to disperse the sediment to nearby mudflats and salt marshes. The Mud Motor is part of the Living Lab for MUD (Multifunctional Use of Dredged sediment) by Ecoshape and its partners that carries out five pilot projects to develop knowledge about the sustainable use of sediment.
The Mud Motor project showed that the feasibility of a Mud Motor depends on an assessment of travel time for the dredger, the effectiveness on salt marsh growth, reduced dredging volumes in a port and many other practical issues.
Sediment and salt marshes
Martin Baptist joined us as a speaker at our latest workshop on Sediment Management in Ports to present his perspective on sediment. He shared his research on the beneficial use of dredged sediment to enhance salt marsh development by applying a “Mud Motor” and by constructing salt marshes.
Sediment management is a necessary part of port maintenance and development that ensures ports’ ability to support big vessels and large volumes. The use of dredging technology differs and the most sustainable solution may also differ depending on each port. However, the disposal of sediment is necessary for many ports and can cause issues. Re-using sediment for salt marsh development is a sustainable way of using existing materiale.
Martin Baptists’ research have improved our understanding on transport processes in the channel and on the mudflats and salt marshes and provides guiding principles for future application of sediment management in salt marsh development.
Knowledge Transfer for the Topic: Sediment Management between Ports, Industry, and Environmental Research
Groningen | Oldenburg, October 29, 2019
The tidal currents keep the sea floor in perpetual motion. These currents cause the formation of sand and mud deposits that can affect maritime ship traffic. In order to ensure access to the ports and port facilities, the waterways must have a certain, guaranteed depth. Many port companies in the North Sea region are facing the same challenges: on the one hand, they must ensure smooth port operations and, on the other hand, reduce their ecological footprint.
The port companies Niedersachsen Ports and Groningen Seaports are conducting a workshop in Eemshaven, in which experts are working on issues concerning an efficient management of sediments and the handling of dredging material in ports. What is the impact of current and future sediment movements in the North Sea and the rivers on the sediment entry into ports? How can ports respond to changing framework conditions in an environmentally responsible, yet most efficient manner? What technological developments promise the highest benefit when it comes to warranting safe access to the ports and improve their ecological footprint?
Joint Solutions for Innovative Approaches
“From our experience we know that we can best answer questions within networks and collaborations. This is a great way to come up with joint, innovative solutions. Everyone benefits from it, but it is the Wadden Sea World Heritage Site that benefits the most”, Dr. Matthäus Wuczkowski, Sustainability Manager at Niedersachsen Ports, explains.
German, Dutch and Belgian experts from port industry, industry, research, and environmental protection exchange their practical experiences, share their knowledge about ongoing projects and about the latest research findings.
The National Park Administration for the Wadden Sea National Park of Lower Saxony (Niedersachsen), the Flanders Marine Institute, and the Ludwig-Franzius-Institute are delivering lectures on current research projects around the topic of sediment movements in the Wadden Sea and the impact of released pollutants. Additional emphases are placed on the introduction of efficient dredging technologies, as well as the alternative and environmentally compatible handling of the dredge spoil.
The EU Project DUAL Ports
Niedersachsen Ports has designed this workshop as part of the European project DUAL Ports, which was initiated in 2015. It is funded by the EU and the Interreg North Sea Program. DUAL Ports brings ports, companies, and scientific institutions from Belgium, Germany, the Netherlands, Denmark, and Scotland to the table. The objective of this collaboration is the joint development of solutions and approaches for the long-term reduction of CO2 emissions and pollution caused by the activities of the port industry. The exchange of knowledge between the partners and the resulting synergies are intended to support and accelerate the development and implementation of sustainability innovations in ports.
Further information about the project DUAL Ports is available here: www.northsearegion.eu/dual-ports and www.dualports.eu
The Workshop-Agenda is available here: https://www.nports.de/fileadmin/user_upload/Sediment_Workshop_Eemshaven_Agenda.pdf
