Food for Thought, New Materials

Recap SYMBIOSIS deep dive: Phytoremediation, cleaning our soil with plants

BlueCity Symbiosis Lowres-Jacqueline Fuijkschot-24

A group of around 20 people, comprising students, policymakers, designers, and entrepreneurs joined the conversation on phytoremediation. To help understand the topic, it started with a presentation on phytoremediation by Freek van der Heuvel from BioClear Earth. This blog captures the discussion and key insights of the deep dive and is written by Thomas Hofman, working at PaperInnovator.

Explaining phytoremediation

Phytoremediation consist of multiple factors: extraction, stabilization, degradation, stimulation and volatilization. It is the process of “cleaning” soils and waters and capturing impurities in Willow trees are able to perform most of these processes. Freek van der Heuvel named four different ways his company used phytoremediation:

  • Willow trees are being used by BioClear for the phytoextraction of heavy metals. There is a project in Appingedam, the Netherlands, where an old factory ground, contaminated with heavy metals, is being remediated by these willow trees. There is no time restraint, so ideal for phytoremediation with willows.
  • Next to this, hydraulic control is also taking place with willows: groundwater control by plants instead of by pumps or mechanical devices. BioClear Earth shares projects with tree wells, these are able to control contaminated groundwater. These projects currently run in the Almelo region. Trees used are summer oak (zomereik), fledder elm (fladderiep) and poplar (populier). They developed a straw system to reach deeper ground.
  • Helophyte filter: These can be vertical, horizontal or vloeivelden. Able to produce clean biomass.
  • Water corridor: Removal of pollutants and nutrients. Use of microorganisms, fixate pesticides. So far only researched in the lab setting. Pilot just started in a rural area.

Plant growing in BlueCity

After this presentation, a lively discussion started with the group. Which plants have potential for phytoremediation? Different plant species can do this. There is a choice between fast growers and accumulators. Both have their benefits. Young plants generally grow faster. Some points of attention were shared:

  • Use of the biomass, specifically the willow trees. The heavy metals accumulate in the trees. Lead and cadmium stay in the root system, while zinc and copper accumulate in the leaves. At the moment, the biomass is burned for energy. Could there be other uses. Problems with contamination, for example if the trees are used for furniture or consumer goods. The heavy metals are stored in proteins and incorporated in other compounds. Are they then still harmful? Immediate water solubility or the potential for the release of these metals has to be taken into account. Perhaps the biomass can be used as a food stock for other organisms, for example degradation by fungi and bacteria. Bypasses immediate heavy metal concerns.
  • It was argued that phytoremediation is a natural process. While man made projects could be able to significantly improve the rate at which phytoremediation takes place.
  • Profitability is achieved by scaling up the process. More biomass means that it could be profitable. Space is required, which is a problem in small countries (Netherlands).
  • At this point, the discussion shifted to arguments on regulation needed to force companies to focus on sustainability. How can the larger polluting companies be forced to remediate the contaminated ground. There was a general consensus that there are too many regulations. It was proposed to from regulation free zones, where there can be experiments on circular challenges. It was proposed that regulations hold back progress.

Key learning points

  • It is possible to build with more bio-based materials
  • New regulations are needed for polluting companies
  • More freedom to experiment
  • More long term focussed business models. Change in societal expectations is needed.
  • Choose the battles. Focus on progress.
  • Change the consumer. To change the society as a whole.

This blog is the result of a two-hours deep dive: a conversation at the start of BlueCity’s annual SYMBIOSIS symposium.

Author: Nienke Binnendijk
Picture deep dive: Jacqueline Fuijkscho
Picture plant: Sophie de Vos