The latest in indoor air quality technology at Drexel University’s new Papadakis Integrated Sciences Building in Philadelphia, Pennsylvannia, is the original air filtering oxygen producer, the plant, as featured in the atrium’s great showpiece, a vertical wall of living plants, 20 feet wide, rising five stories (75 feet) in height. It is the largest such wall in North America and the only one at a U.S. university.
Scientists and students at the university are currently studying the biowall and the plant and microbe communities responsible for its air filtration properties to get a better understanding of how the whole thing works. Dr. Michael Waring, an assistant professor in the university’s College of Engineering who specializes in indoor environmental engineering, will focus on the chemical and physical aspects of the living wall, while two biology faculty members from the College of Arts and Sciences, Dr. Jacob Russell and Dr. Shivanthi Anandan, will focus on the wall’s biological functions.
Drexel’s biowall consists of over 12 different varieties of tropical plants that don’t need soil to grow. These plants embed their roots between two layers of woven, porous material (similar to that of a kitchen scrubbing pad); water trickles down the wall between these layers, providing plant roots with nutrients and hydration.
This water is also an important element of the wall’s air filtering properties, as fans running behind the wall continuously pull contaminated indoor air through the biowall’s porous materials, causing volatile organic compounds to naturally dissolve into the water and become available to bacteria and fungi on the plants’ roots. These microbes then consume and break down the VOCs into benign products (primarily carbon dioxide and water), and virtuous cycle continues.
Drexel’s biowall comes courtesy of NEDLAW Living Walls, which estimates that it is capable of generating between 16,000 and 30,000 cubic feet of ‘virtual’ outside air per minute.