Permeable Reactive Bio-Barriers
- shriyadwivedi186
- 10 minutes ago
- 3 min read
Treated ground water is not directly consumed by us. It's used in public drinking water supplies, agricultural crop irrigation, and industrial manufacturing processes like cooling towers and underground aquifers. But how do we actually "treat" groundwater? Well, one way is by modeling filtration infrastructure after actual biofilms. In this article, let's take a look at how taking inspiration from nature's controversial microscopic living beings benefits us.
What Are Biofilms?
Biofilms are a community of microbial cells that adhere to a surface in moist or aqueous environments. This community of cells doesn't just have to come from one bacterial species, but could actually contain various types of bacteria as well as fungi, algae, and yeasts all thriving together in one glue-like substance. A biofilm's structure is due to the extracellular polymeric substances (EPS) or sugary molecules attaching to each other, creating a resistant, 3-D matrix.
Biofilms could be found in many different environments as long as they have adequate nutrients, moisture, and a solid surface to attach to. In this way, biofilms have been identified on rocks near rivers, unwashed shower stalls, and even on the surface of our intestinal organs and dental plaque! However, not all biofilms are bad, and not all are good.
The Good and the Bad
Many people believe that biofilms are automatically a threat to an environment; however, the effect of a biofilm depends on the different abiotic factors of the environment. It's no question that biofilms found clogging and contaminating our water distribution systems, accelerating industrial equipment corrosion, and reducing heat in power generators cost the U.S. billions of dollars each year. However, it's ability to act as a physical shield to any antibiotics or pollutant chemicals that come across is a natural marvel to other ecosystems. The slimy matrix of a biofilm is so closely stranded together that its surface creates a metabolically active film that can actually neutralize pollutants- not only blocking those chemicals, but also reducing its effects on the surrounding organisms.
Biofilms are essential in filtering municipal and industry wastewater, bioremediating hazardous waste sites, and forming bio-barriers for soil to prevent contamination. All of these processes require a strong biofilm network to ensure cleanliness and efficiency at all times. Therefore, researchers and engineers look at specifically bio-films to model bio-barriers for mechanical structures to filter groundwater.
How Do We Use Biobarriers?
For the past two decades, teams of engineers have modeled large-scale biobarriers that mimic the same selective permeable membrane that biofilms have underwater, cleaning contaminated groundwater. These structures are called Permeable Reactive Bio-Barriers (PRBBs).
(but how do we make them?)
PRBBs are built by first building a narrow trench in the same path that contaminated groundwater is flowing. Then, the trench is filled with reactive agents such as iron or limestone that breaks down contaminants within the water. To make the barrier more permeable, the reactive material could be mixed with materials such as sand, yielding cleaner groundwater.
My Take
Understanding PRBBs is integral in expanding knowledge of water filtration methods, but the marvel of framing its system around a biofilm's EPS cements the idea that nature itself can show us how to remediate itself. In fact, such engineering projects show a shift in engineered solutions. Now instead of fighting against nature, we are working alongside it, preventing disruption of ecosystem.
Constructing a PRBB is seen as relatively inexpensive and uses little to no energy, allowing the natural flow of groundwater to promote filtration. By leveraging microbial activity and natural chemical reactions, these systems treat contamination directly at its source rather than transporting it elsewhere for processing.
More broadly, I believe PRBBs reflect a shift in environmental engineering toward biomimicry. As water challenges intensify, solutions that are passive, adaptive, and rooted in natural processes will likely become more important because they scale with the environment instead of working against it.
Sources: