|
The 22-foot-wide, 80-foot-tall biowall at Drexel
University is not only beautiful but also purifies
indoor air. Considered as North America’s largest
living biofilter, it consists of over 12 different
varieties of tropical plants that grow in the absence
of soil. The plant roots are embedded between two
layers of woven, porous material. Water is
recirculated down the wall between these layers
providing plant roots with nutrients and hydration.
Bacteria and fungi found on the plants’ roots utilise
harmful airborne pollutants as food, breaking down
volatile organic compounds (VOCs) like benzene,
toluene, methyl-ethyl ketone and formaldehyde into
carbon dioxide and water. It has been estimated that
such a biowall is capable of removing 60-90% of
pollutants with a single pass while reducing overall
airborne pollutant concentrations by more than 25%.
|
