Working together with the municipalities of Frederikshavn, Hjørring, Jammerbugt and Thisted, KIMO has been examining the recycling potential of washed-up HDPE / PP plastic. Our activities were supported by the Clean Coastline project.
The Importance of Sorting
Experts in reprocessing and recycling of plastics informed the project team that sorting plastic into single polymer groups would be critical. Proper sorting ensures the best quality of recycled material. The municipalities tested several sorting methods during the project period.
Frederikshavn Municipality tried to collect and sort material using machine collection and a mobile sorting plant. Larger objects could only be collected by hand. The municipality concluded that it was possible to collect washed-up litter with a machine, but the cost of subsequent sorting and disposal of the mixture of litter, stones and sand would be disproportionately large. Sand and stone could be discarded using a drum machine and / or a water bath. This reduces the amount of waste disposed of and some of the plastic material is separated out, but it also requires extra equipment and extra person and machine hours.
Employees in Hjørring municipality were trained in the sorting of washed-up litter. The purpose was to gain more knowledge about the amounts of plastic and other materials collected on municipal beaches. By gaining knowledge and on-the-ground experience of different types of plastic, the municipal employees were able to optimize the collection and sorting of different polymers resulting in less incineration and more recycling.
Jammerbugt municipality tested mechanical sorting of marine plastic in cooperation with I/S Reno Nord waste and energy company. The company uses an automated plastic sorting plant, and the experiment showed that it was possible. Washed-up waste was mixed with household waste at the plant. Unfortunately, it was not possible to ascertain how much was sorted for recycling and how much was discarded by the plant. One drawback is that objects that are too sandy, contain chemicals, or are too large, must be disposed of at the municipality before handing over. Yet another task that requires employee resources.
The conclusion is that sorting can be done both mechanically and by hand, but in order to obtain pure waste streams for optimal recycling of marine plastic, the municipality has to commit extra resources.
Plastic from the Danish west coast: is there sufficient volume to make recycling feasible?
KIMO in collaboration with four northern Jutland municipalities sorted washed up plastic for recycling. Fishing boxes, canisters and buckets made from HDPE and HDPP plastic were separated out. In total, approximately 3 tons of hard plastic were separated out for the project. Some items were discarded due to poor quality or content of chemicals. It was possible to sort up to 2-3 tons of plastic annually from the participating municipalities. A realistic estimate would be approximately 1-2 tons of hard plastic available per municipality per year.
It is estimated that 10 – 25 tons of HDPP / HDPE plastic could be available for recycling annually if all the municipalities of West Jutland sorted the material. KIMO’s investigation of washed-up waste from 2007-2009 showed that approx. 1,000 tons of washed-up waste was collected and disposed of on average. The figure is only used as a guide here, since there is no recent inventory. If 10-25 tonnes could be sorted from the other circa 1,000 tonnes that the west coast receives on an annual basis, it will be estimated to be 1-3% of the collected material.
The conclusion is that it would be very complicated and costly to separate out a relatively small amount of hard plastic making a viable business model for recycling Western Jutland marine plastic seem unlikely.
Examination of recycling potential of washed-up waste
A review of containers with mixed and unsorted, washed-up waste can give an estimate of what can be expected in a typical municipal beach cleaning. KIMO Denmark and the company Strandet sorted and categorized waste from some of the containers that Danish partners in Clean Coastline project provided in 2018.
At Frederikshavn Municipality’s waste facility in Skagen, KIMO investigated a random container with beach waste. The waste originated from the municipality’s own collection by hand and machinery and from voluntary beach cleaning.
The material in the container totaled 2,467 kg. By weight, most of the waste was only suitable for incineration (60.8%). These were mainly bags containing articles that were too small, dirty or of mixed materials. Plastic bottles, glass and other immediately recyclable items were removed by inspecting the bags.
Equipment from fishing in the form of nets and ropes, gloves etc. was separated out. Larger fishing related objects constituted 27.5% of the weight. This equipment cannot be recycled and is typically also sent for incineration. In terms of weight, approx. 11.7% of the total waste in the container had potential for recycling. Processed wood, which is the heaviest fraction, was 5.7% of the weight of the waste. Glass was 0.92% of weight and metal 0.32%. 4.1% of the weight was HDPE plastic. Other plastic consisted of PET bottles (0.33%), PE plastic bottles (0.19%) and PP plastic bottles (0.08%).
Strandet I/S conducted a similar analysis of washed-up waste for Thisted Municipality. Their analysis concluded that only approximately 1% of the collected waste is HDPE, which has the potential for recycling. In this study, less than 2% of the collected waste was immediately recyclable. Much of the collected waste was considered suitable only for incineration.
Fish boxes as recyclable plastic material
In Hjørring Municipality, the largest plastic objects were sorted out. KIMO Denmark counted 98 fish boxes in November 2018. This corresponds to approximately 392 kg of HDPE plastic. In addition, there were canisters and other HDPE items weighing approximately 100 kg. Some fish boxes were very dirty. The surface was often covered with sand, algae and shells. Some of the growth could be brushed off by hand but a high pressure cleaner was also used. After cleaning with a high pressure cleaner, the cleaner product is more suitable for reprocessing and there is less wear on the machinery. Fish boxes are relatively easy to sort and clean, and most are made of the same plastic type. There is a considerable amount of recoverable plastic material to be found in fish boxes. On the other hand, steps should also be taken to prevent their loss at sea in the first place.
It takes a lot of resources to recycle washed up plastic – even HDPE
KIMO asked Hjørring Municipality for a statement of the number of working hours and resources used in connection with the preparation of HDPE plastic for recycling. The statement does not include transport costs or other environmental factors. In practice, municipal employees do not work exclusively with marine plastic. The municipality’s best estimate is that the collection of the recyclable part of the washed up plastic requires approximately 450 person hours corresponding to circa DKK 160,000 per year. The machine hours are calculated in the hourly rate. After the collection, the municipality used an estimated 48 hours (circa DKK 15,000) on sorting. In addition, 63 hours (circa DKK 20,000) were spent on cleaning/high pressure washing of the objects. The amount of water used for cleaning was approximately 5 cubic metres.
Thus, in 2017 Hjørring municipality spent in the region of DKK 200,000 to prepare recyclable HDPE plastic material for reprocessing. With 900 kg of HDPE being delivered by the municipality for recycling, this equates to DKK 222 per kg in expenses for the municipality (exclusive of costs to transport the material to a recycling company and excluding reprocessing costs).
Are there business opportunities for „marine plastic“ in Denmark?
KIMO Denmark sent the washed up plastic collected from the municipalities for recycling and reprocessing. It is possible to reprocess HDPE/HDPP plastic articles for raw material (plastic granulate or powder). It can then be pressed, cast or sprayed in new forms and into new products. The durability and strength of the recycled material in „marine plastic“ should be investigated when a new product is desired. The strength of the material can be weaker compared to ordinary recycled plastic or new plastic.
The experience from Project Clean Coastline shows that recyclable material can be collected relatively easily from the beach, but it can be costly and difficult to sort into separate streams for recycling. It has not been possible to find a sustainable basis for sorting marine plastic in Denmark. A sustainable business model will mean that collection, sorting, reprocessing and production are made as close to the source (coast) as possible. The company Strandet I/S, which was established in step with the project and in close cooperation with Thisted Municipality, uses this business model.
Project Clean Coastline
Marine litter is a common challenge for the municipalities in the Kattegat-Skagerrak region (KASK region). Project Clean Coastline was a joint Scandinavian project from 2016-2018 with funding from Interreg Øresund-Kattegatt-Skagerrak. The main objective of the project was to find innovative methods for dealing with washed-up waste, investigate recycling possibilities and reduce waste entering the sea at local and regional level. It was a collaboration between 34 partners, including research institutions, waste companies and public administration. In Denmark, the project contributed, amongst others, to the development of the Nordic Beach Clean Day, the Coastal Lottery (KIMO Denmark) and the company Strandet. For more information, please download the project report.