Wealth from Sludge

This post originally appeared on Circulate, an online location for news and editorial insight on the circular economy and related subjects from the Ellen MacArthur Foundation.

The most common examples of the circular economy in practice are in sectors like consumer electronics — high value products and technologically focused. Indeed, many of the initial opportunities, or “lowest hanging fruit”, have been in developing business models around reuse, refurbishment and remanufacturing, and it is likely that the economic gain from those opportunities will continue to be lucrative. However, the transition to a circular economy will also require the creation of new flows of resources and materials.

In some cases, it is possible to create cycles where products and their materials are kept within “controllable loops”, but changing the global economy will also require the re-utilisation of waste streams that can not be cycled in this way. One of the circular economy’s fundamental principles is that “waste equals food”.

Significant progress is being made in that direction already and in many cases it is being led by companies previously prescribed the role of simply collecting and dealing with the waste created by a linear economy.

As economies are changing and valuations of materials evolve, it is becoming evident that former waste managers are moving towards being “material managers”. Waste management sector companies are actually one of the best placed to take advantage of the opportunities created by a transition from a linear to a circular economy, by rethinking their traditional place as “end-of-pipe” actors.

Johan Borje, director of marketing and business development at Ragn-Sells, a Sweden-based waste sector company told Circulate: “It is an evolution where the demands on us — from customers and competition — is to extract as much material out of waste streams as possible.”

Borje went on to discuss the company’s changing relationship with its customers:

“We see us further integrating into the business processes of our customers. This will help to reduce waste, recycle more of the waste created, as well as enable reverse logistics services”.

f course, the strongest driver of maximising the value of waste is the economics. In one example, Ragn-Sells is working to extract phosphorus from sewage sludge to be used in agriculture and to re-enter the biological cycle as a natural fertiliser.

Sewage sludge is possibly the ultimate characterisation of waste. However, Ragn-Sells — working through subsidiary EasyMining Sweden — have identified it as a flow of nutrients with potential value to the economy.

Ragn-Sells sends 160,000 tonnes of sewage sludge directly to agriculture annually for fertiliser (already around 80% of the amount it handles), but by utilising EasyMining Sweden’s “CleanMAP technology”, the company is now also aiming to extract valuable nutrients from the sludge — the most notable of which is phosphorus.

For many, thinking about phosphorus might bring back painful memories of trying to remember the periodic table, but its role and importance in our economic system is frequently under-stated. It is an essential chemical element for life and plays a critical role in our food systems as a required nutrient that typically enters the food chain by being drawn up from the soil through plant roots. Like many of the world’s essential resources, it is also finite, but it does cycle naturally in the environment. The problem is that increasing food demands from growing populations have been met by modern intensive farming methods, where high yield crops are generated by irrigation techniques and the use of pesticides, all of which necessitates higher levels of phosphorus being used than occur naturally.


  1. There isn’t unanimous agreement among scientists on how much phosphorus is left, but many predict that peak phosphorus will be reached by 2030
  2. Around half of the world’s phosphorus reserves are found in the Middle East
  3. Most commercial compounds of phosphorus are used in fertiliser
  4. Phosphorus is not found in nature on its own, but is found in a number of minerals
  5. The process of mining and extracting phosphorus is energy intensive.

Credit: Ragn-Sells

In the past, a decline in yields was prevented by a combination of fertilisation using farm animal manure and crop rotation, which would allow fields time to recover their nutrients. However, performance, at least in terms of size of yield, is better when growth is supported by the use of fertilisers and pesticides. Those innovations have enabled increasing production of commercial farming, but have also created a higher demand and need to dig up phosphorus-bearing minerals to transform into fertiliser. The chemical process involved is energy intensive and the amount of phosphorus that can be dug out of the ground is finite. Some estimates predict that “peak phosphorus” will have been reached by as early as 2030.

Ragn-Sells’ vision is to create a phosphorus cycle, where high quality sludge is fed directly back into agriculture as fertiliser, while low quality sludge can be processed, and the phosphorus extracted for return as a raw material to the fertiliser industry.

So far, CleanMap has only been used on a prototyping scale, but Borje told Circulate that he is confident that it can be scaled up successfully:

“The phosphorus product does not have to go through the phosphate industry, but can be directly sold to a distributor or end consumer. We are convinced of the commercial viability, as long as we secure large-scale volumes. There is no loss in quality compared to alternatives commercially available today.”

Borje added that the first large scale plant is now being designed and the installation is expected to be ready within the next two years.

Making use of waste, providing a link in the chain of a biological cycle and economic advantages, the Ragn-Sells’ phosphorus recovery project takes advantage of many of the principles of the circular economy and will also be good for business.

The company’s activities in this area are not limited to phosphorus either. Ragn-Sells runs a number of other projects working in a similar vein including; the extraction of heavy metals from industrial sludge, recycling of ashes through better metal extraction and separation of hazardous substances, REE extraction from industry residuals, landfill mining, reuse of textiles and constructions, and city logistics.

These projects have a few things in common. They require imagination and invention to think about by-products differently and to exploit their benefits, often by working in new cross-sector collaborations with different industries. Ragn-Sells is among the early movers in the sector exploiting opportunities as valuations of materials change, and as the idea that “waste” should no longer exist grows stronger in business and in public opinion. More and more, waste management companies are moving from damage minimisation towards the management of resources, which is more promising in terms of building resilience and economic viability for the global economy in the long-term.


Seb is the content coordinator at the Ellen MacArthur Foundation and writes regular news pieces for Circulate. You can e-mail Seb at seb.[at]circulate.org

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