Sustainable Growing

If Grodan were a country

Ellen Seelen
August 29, 2023

It would be one of the most successful recycling countries in the world. In 2022 alone, Grodan achieved a recycling rate of 65%! By comparison, Germany, considered the most efficient recycling country in the world, has a recycling rate of 68%. Nevertheless, we are not satisfied yet and are working on better and more recycling solutions worldwide.

Can you recycle Grodan stone wool?

Absolutely! The same properties that make stone wool such an effective growing media for cultivators actually make the material attractive for recycling markets.

Grodan recycling accounts for almost 60% of total ROCKWOOL recycling. Grodan products are recycled differently, though. This is because the Grodan stone wool products used have a different composition to ROCKWOOL stone wool products.

So how do we do that?

Grodan stone wool has several secondary applications including: feedstock for brick manufacturers, compost, stone wool and green roofs. We are always looking for new & innovative recycling solutions and new recycling providers.

From old to new. Circular solutions

ROCKWOOL's Rockcycle® program is a circular economy solution for the Netherlands and Denmark, which brings used stone wool back to factories so it can be re-manufactured into new stone wool products. Grodan stone wool can contain up to 75% recycled materials.

Clay for bricks

Used stone wool is a desired feedstock for brick manufacturers. Less energy is required to produce the finished bricks in the manufacturing process and the stone wool fibres add strength to the finished products.

Compost & Potting Mix

Compost is one of the main recycling applications for the North American market, where used stone wool is treated as a beneficial use amendment. The stone wool adds porosity, added water holding capacity, and additional nutrients.

Erosion Control

Used stone wool is processed and bagged to create erosion control devices or “waddles.” The stone wool is an alternative media to sand and straw. Grodan is presently collaborating with a recycler to commercialise this option for different markets.

Green Roofs

Processed used stone wool has shown to meet FLL Green Roof Guidelines. Stone wool’s natural water holding capacity is an ideal additive to green roof substrate brands.

Other solutions

We are constantly innovating and exploring for newer and better applications as we strive to make stone wool the most recycled product in the world. A few examples: wastewater filtration, expanding green roof applications, and soil for cowsheds & trotting tracks.

9,600 full trucks a year

As part of its commitment to the circular economy, Grodan has established a network of recycling facilities that accept, process, and recycle over 9,600 full truckloads of stone wool across North America, Europe, Asia and Australia. More than half of Grodan stone wool growers participate in recycling every year. Grodan’s recycling managers support growers by finding and building new recycling markets.

Used rock wool at a depot in the Netherlands
Used rock wool at a depot in the Netherlands

How about the future?

ROCKWOOL International is committed to sustainability, especially circularity. This means we are working on the following expansions and improvements:

  • Offering recycling services in even more countries 
  • Collaborating with new recyclers to provide localised solutions
  • Assisting growers in helping meet their specific recycling challenges
  • Develop products that are even easier to recycle and reuse

As we continue to expand recycling options for stone wool consumers, the goal is to make Grodan stone wool one of the most effectively recycled products in the world

3 full-time recycling managers

We have three experienced recycling professionals, who are core components for our Application & Development team and oversee recycling challenges and opportunities worldwide.

Yianni Monahan

Product Lifecycle Manager, North America, Grodan

Yianni is a mechanical engineer and has been working in the waste and recycling sector for more than 10 years. Yianni grew his specialty in recycling and solid waste where he launched a start-up focusing on energy recovery technologies.  

“For me sustainability is not just a buzz word it’s a commitment to action. That’s why we are focused on short & long term goals and how we can continue to make recycling stone wool more and more ideal for our growers”

Tom Vitters

Manager Recycling Europe and Export Markets, Grodan

Tom has more than 30 years of international experience in the waste industry and has set up several international take-back systems for challenging waste streams on behalf of leading waste management organisations in the EU.

"The versatility of the waste world makes it exciting; logistics, processing technology, legislation and finding solutions and then also doing something good for the environment"

Wouter Taal

Recycling Manager, Grodan

Wouter has been working in the world of waste and recycling for more than 9 years. Before joining Grodan, he worked at an international waste management company where he coordinated treatment processes that allowed waste to be used as raw material.

"Working within the world of recycling is both challenging and rewarding. Providing solutions for waste streams is a challenge, seeing how we can influence the environment is a just reward”


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