Largest Biowall in U.S. Comes to Life

A 22-foot-wide, 80-foot-tall biowall stands at the heart of Drexel University’s Papadakis Integrated Sciences Building.

Drexel’s biowall is North America’s largest living biofilter and the only such structure installed at a U.S. university.

It consists of over 12 varieties of tropical plants that grow in the absence of soil. The plant roots are embedded between two layers of porous material. Water is recirculated between these layers to provide plant roots with nutrients and hydration.

The wall uses the natural respiratory properties of plants to cool the indoor air in the summer and function like a humidifier in the winter. It also naturally filters the air, directly improving IAQ.

It is estimated that biowall systems can remove 60-90% of pollutants with a single pass while reducing overall airborne pollutant concentrations by more than 25%.

The process starts with bacteria and fungi at a plant’s roots that use airborne pollutants as food. These harmful compounds are delivered to the microbes by actively drawing air through the biowall via the HVAC system.

This process breaks down VOCs such as benzene, toluene, methyl-ethyl ketone, and formaldehyde. The purified air is then redistributed throughout the building.

To better understand the benefits provided by this green technology, university researchers will study how well the biowall works, how different plant types and microbes vary in their abilities to purify VOCs, and which of the root-associated microbes are involved in VOC degradation.

The research will transform the biowall into a living laboratory, helping to quantify the benefits of the structure while shedding light on the mechanisms by which plants and their microbes improve air quality.

This work should help to identify plants and microbes that are efficient VOC degraders, paving the way for the design of more efficient living walls and healthier indoor environments.