Liberty Industrial contacted Keenan Recycling seeking a sustainable solution for marine growth removed during the decommissioning of a North Sea vessel. While Keenan Recycling processes over 2,500 tonnes of shellfish waste annually, this marked its first encounter with this specific waste stream.
Keenan Recycling conducted a risk assessment to ensure the marine growth wouldn’t negatively impact the composting process or the final product. Following a sample analysis and confirmation of minimal contamination, the next step involved securing regulatory approval.
As the specific waste category wasn’t listed on Keenan’s existing permit, special permission from Scottish Environment Protection Agency (SEPA) was required. This involved categorising the waste according to the European Waste Catalogue and obtaining approval for a trial basis.
The composting process
Keenan Recycling utilised an in-vessel composting system at its New Deer facility. The process involves:
- Shredding: The marine growth is shredded to create a homogenous mixture with increased surface area for microbial activity
- Blending: The shredded growth is combined with garden waste and oversize woody material to achieve the optimal composting blend, ensuring proper nitrogen content, moisture and oxygen levels
- In-vessel composting: The mixture is loaded into vessels where natural microbial activity breaks down the organic material, generating heat and sanitising the waste
- Maturation and screening: Following the initial composting phase, the material undergoes maturation and screening to remove larger pieces and any plastic contaminants
- Final product: After a final maturation period, the composted material meets BSI PAS 100 standards, transforming it from waste to a valuable soil improver
Benefits of recycling marine growth waste
- Environmental advantages: Recycling diverts organic waste from landfills, promoting sustainability and reducing methane emissions.
- Agricultural applications: The resulting compost boasts beneficial properties for local agriculture. Rich in nutrients like N, P, and K, it increases organic matter, improves soil biodiversity, and acts as a natural liming agent, potentially reducing reliance on chemical fertilisers.
Looking ahead
Keenan Recycling said this successful collaboration demonstrates the viability of recycling marine growth waste while contributing to a more sustainable future.
“It was very pleasing to be able to provide an outlet for this waste stream though as I hate to see any organic waste getting landfilled. It’s vitally important that there are alternatives from an environmental perspective but also as there will be a complete ban of biodegradable waste to landfill at the end of next year,” said Gregor Keenan, operations director at Keenan Recycling.
“Going forward, we really just need to know what we’re getting in terms of the waste type, quality, where it’s from and when it will be delivered. Last year, we processed over 105,000 tonnes at our New Deer site so there’s a huge amount of admin involved for a relatively small team,” added Keenan.
“This collaboration with Keenan Recycling showcases our commitment to finding innovative and sustainable solutions for decommissioning waste. Recycling the marine growth demonstrates the potential for responsible waste management in the industry, while creating a valuable resource for agriculture. We look forward to working together on future projects to minimise our environmental impact,” added Lawrence Henderson, project director, decommissioning, at Liberty Industrial.
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