Technics tests water purification with plants!

The most sustainable water is the water you don't use. Or reuse, of course! At Bio-Planet Tournai, we're testing water purification on a small scale. The purifiers at work? Helophytes!

Purifying plants

Helo-what? R&D engineer Iris Deseau: "Helophytes are a group of water plants with their roots under water and the leaves and stems above the waterline. In Tournai, we work with reeds, but plants such as the yellow flag and purple loosestrife are helophytes as well. The purification installation consists of two layers: the plants on top, with porous pellets underneath. The combination of the pellets and the reed roots is the ideal environment for the micro-organisms that purify the water."

Why is the first helophyte filter located in Tournai? Iris: "Some additional pipework is needed for the installation, making it more difficult to test the system on an existing store. The new construction in Tournai came at the perfect time. We were able to easily add the extra piping to the design. Moreover, Bio-Planet was – logically – very enthusiastic about the biological nature of the water purification. So everything added up perfectly."

We use the purified water to flush the toilets; this makes up about 25% of the store's total water consumption.

Testing quality

With this first helophyte filter, we especially want to discover what quality of water the mixed waste flow yields after purification. Do we meet the standards for cleaning water? Because then we could also start using the water to clean the store. Iris: "We will also examine whether the quality is good enough for infiltration, for example. This is already allowed in the Netherlands; if we can prove that we achieve a sufficiently pure quality, we might be able to set some things in motion in Belgium as well."

Iris: "We are also examining which factors influence the quality of the water, and how big that impact is. Is the quality lower in the winter? What impact do the various components in the waste water have? Do we need to add more or less oxygen to the water based on that? We will be looking for the answers to these questions in the next months."

Next steps

Where will the next 'plant filter' be installed? Iris: "For now, we are still in a test phase, which we hope to learn from as much as possible. It's a new system, and we want to discover whether and how it fits in our 'water puzzle'. A big advantage is that the system uses waste water. Contrary to rainwater for example, this is a constant 'source' because the volume of waste water doesn't change much from day to day."