Biological air cleaning system

Biological air cleaning system (BACESS)


In 1989 after nearly 20 years research NASA published that the superior air purification was carried out by a system consisting of plants and soil. The root zone system BioVentic is an air treatment system based on light soil filter with vegetation. Contaminated air is pressed through the root zone filter by a ventilator. Energy consumption is 38 watt/h. Installation has been set up in Denmark, Sweden, Netherlands, USA and since 2007 in Greenland.
Unilever, Rotterdam

This study has been made with a view to objectifying root zones possible cleaning efficiency in slightly different setups measuring selected parameters which normally are used when examining indoor climate. While NASA has been working with tests under strictly controlled conditions, this present study was on practical plants in operation. The study has shown that especially soil covered with limestone has the largest cleaning efficiency and does not give unintended side effects. Based on the present tests root zone installations seem to be effective and they can certainly strengthen the indoor climate to a great extent.


The invention is based on the knowledge that soil, which contains microorganisms and serves as a substrate for plants, has a capacity to remove harmful particles and gases from the air.

Measurements on installations have shown the following results:
  • Health and comfort condition based on questionnaires from Glostrup Hospital, Denmark showed that health and comfort problems are in average reduced by 50%.
  • Temperature is reduced due to high evapotranspiration from the soil media and the plants. The temperature reduction is approximately 3 °C in the range of 2 – 5 °C. The cooling reduces the relative humidity and evaporation helps raising the relative humidity.
  • PM10* was significant reduced 2-29% in Post-Denmark office and 15% in Transform office comparing with and without air treatment.
  • At bank office “Fælleskassen” (Copenhagen, Denmark) it was observed that the installation could clean for PM10 relative to the external reference approxemately 75%, and relative to the internal reference at “Fælleskassen” 50%.
  • Chemical reductions tested in climate chambers (Aarhus University, Denmark) resulted in an efficiency of 90% when comparing with and without air treatment.
  • 22 smell based chemicals are tested between intake and outlet with cleaning efficiency 80-99% for the chosen chemicals and 25-71% for ammonia.
  • Bacteria were reduced with 81-95% when comparing values between intake and discharge from the root zone.
  • Micro fungi in the air were reduced by 89% when the soil was covered with limestone. However the same test, without limestone, increased the emission of micro fungi by a factor of 3.
  • Efficiency based on number of fungal spores/m³ air showed a 81% reduction after passing through root zone covered with limestone. However yeast cells from plants can be released and raise concentration nearby the vegetation.

* PM10: Particulate matter up to 10 micrometers in size, ”big” particles between 2.5 and 10 micrometers in smoke, dust and dirt from factories, roads and farming, as well as mould spores and pollen.

Suitable plant genera are for example:
  • Chrysanthemum morifolium
  • Dracaena deremensis
  • Philodendrum domesticum
  • Chlorophytum comosum
  • Epipremnum aureum
  • Schefflera ssp.
  • Sansevieria ssp.
  • Spathiphyllum ssp.            among other possible species.
New improved design

Principle root zone air treatment
Technical layout: Air ventilation per hour should be 50% of the room volume.


Jørgen Løgstrup
Søren Thorhauge Andersen
Bacess A/S and Transform af 1994 ApS
Postgaardsvej 11
9260 Gistrup, Denmark
Patent: EU 1356239, ZL 01822087.8 (China), 6,638,338 B2 (USA)

This is an altered version by Michael Blumberg, by courtesy of the authors.