The disposal of microplastics in our environment has gained considerable attention in the last years as a threat that cannot be ignored. The disposed microplastics in our waters originate from different sources, for example from tiny polyethylene scrubbing particles in creams. However, this is not the only source. During bottom fishing, the undesired disposal of microplastics take place as well. This article shows how the microplastics are disposed into the sea and how Senbis has contributed to develop a solution for this serious issue.

Microplastics due to the use of dolley-ropes.
In the fishery industry, high-value fishing nets are dragged by fishing trawlers over the seabed. During the dragging over the sand bottom, the nets are subjected to severe abrasive wear. To avoid the wear and damaging of the nets, the nets are protected with ropes. These ropes are called “dolly-ropes”. Fishermen knot the dolley-ropes on the nets prior to fishing. During the dragging the ropes spreads into tiny filaments and create a kind of protective “cushion” between the nets and the seabed, see figure 1. As a result, the dolly-ropes will be subjected to wear, not the nets.

Figure 1. Dragged fishnet over the seabed with dolley-ropes [1]

Dolley-ropes are usually manufactured from polyethylene fiber, see figure 2. Polyethylene is not a biodegradable material. Due to abrasive wear, the dolley-rope polyethylene debris remain behind in the sea for a very long time. In due course, the debris will merely break down into increasingly smaller fragments. These fragments could finally become microplastics which are, and can be, taken-up by micro-organisms and fishes. It is estimated that yearly about 25,000 kg polyethylene ends up into the North Sea alone, because of this method [2]. As polyethylene has a lower density than water, birds pick up somewhat larger worn pieces of dolly ropes floating at the sea surface level for constructing their nests. In short: polyethylene dolley-ropes are good for the nets, but not for our environment!

Figure 2. Polyethylene dolley-ropes [Source: Senbis Polymer Innovations]

DolleyropeFree project.
The Dutch government, VISNED (Dutch fishermen’s association) and the North Sea Foundation have expressed their concerns about the dolly-rope issue in 2014. Afterwards the “DolleyropeFree” project was founded. This project is coordinated by Wageningen Economic Research and Wing and the above-mentioned organizations. The material scientists of Senbis Polymer Innovations have in-depth expertise and pilot facilities to develop new sustainable polymer fibers. Therefore, Senbis was involved to develop new and sustainable dolley-rope fiber solutions.

Marine degradable dolley-rope fibers.
During the project, Senbis developed a wear resistant bio-based fiber which degrades in marine environments. The worn debris will degrade into carbon dioxide (CO2) and water during several months. So, the degradation of the biobased Senbis dolley-ropes take place significantly faster than the degradation of polyethylene, which takes centuries. In other words, it eliminates the microplastic issue after a few months. In addition, the degradation of the Senbis biobased dolley-ropes will not leave behind any toxic substances in the sea. As the bio-based fibers have a higher density than water, larger worn fiber particles sink to the sea bottom, preventing birds to pick up the material from the sea surface. Senbis has made extensive efforts to develop the fibers. The spun fiber was tested in practice by applying the biobased dolley-ropes on the fishing nets, see figure 3. It appeared that the wear resistance of the Senbis bio-based dolly-ropes was at least two times better than polyethylene dolly-ropes, extending the dolley-rope durability with at least a factor two as well.

Figure 3. Bio-based dolley-ropes of Senbis tested [Source: Senbis Polymer Innovations]

In conclusion, the sustainability benefits of the Senbis biobased dolly-ropes are: ·      Biobased origin rather than the fossil-based polyethylene, reducing the footprint of the polymer manufacturing phase

·      Two times improved fiber durability, due to the improved wear resistance

·      No microplastics that remain in the sea due to the marine degradability

The challenge today is to reduce the cost price of the bio-based fiber to ensure a wide applicability. This could be done by accelerating the production throughput.

 

Co-development at SPIC-Emmen.
Senbis is located on the Emmtec industrypark in Emmen. At this park there are many facilities available for the development and production of (bio)plastics and applications such as fibers. The Sustainable Polymer Innovation Cluster (SPIC-Emmen) offers these services openly to the market. This gives innovative companies such as Senbis more opportunity to effectively develop new sustainable products but also to upscale these products to mass production.

If you are interested in more detailed information, or how SPIC could help you to create sustainable solutions for your business, please feel free to contact Jan Willem Slijkoord (jw.slijkoord@www.spic-emmen.com) or visit www.spic-emmen.com.

 

By: Jan Willem Slijkoord
Business Development Manager SPIC

Sources:

[1] http://www.vispluisvrij.nl/over_pluis

[2] http://www.dollyropefree.com/blog/23/cleaning+the+nordic+seas+from+dolly+rope