Kombucha: more than just a drink

How this popular drink can help clean our water by being a part of our water filtration system.

Jar of Kombucha on a table
Kombucha is a popular beverage known for its potential health benefits. Image from https://images.everydayhealth.com/images/potential-benefits-of-kombucha-alt1-1440×810.jpg

Kombucha has gained popularity in health and wellness circles for its potential health benefits in the form of an antioxidant and immune system booster. Personally, a cold glass of orange juice in the morning is sufficient for me but I have heard time and time again about its amazing properties from the friends around me. I’ve met their enthusiasm with scepticism but there is no denying that kombucha is quite amazing, just not for the same reasons my friends were thinking of. There is a bigger place for kombucha than just a morning drink to start off the day and that place is an affordable solution to our clean water crisis.

The Refreshment

Kombucha is a fermented tea that is made with sweetened black or green tea and SCOBY (symbiotic culture of bacteria and yeast). The bacteria in the SCOBY consume the sugar in the tea to produce small amounts of alcohol, vitamin B, probiotics and acetic acid. The probiotic properties are what’s most sought after when consuming kombucha as it contains antioxidants which can have the ability to kill harmful bacteria in the body. 

The Water Filter

On top of its success as a beverage, kombucha has also had a big splash in the water-cleaning industry. It offers many advantages as an active component in the water filtration system because kombucha fermentation can be used to create Living Filtration Membranes (LFM). LFMs are untraditional filters that purify contaminants from water using living organisms. This process effectively removes risks to human health such as bacteria, parasites, and some viruses.

The typical manufactured filter, Commercial Polymer Membrane, uses size exclusion to remove impurities. However, they are more susceptible to biofouling as the pores can easily be obstructed. Biofilms are at risk of forming and this vastly decreases the efficiency of the water filtration process.

Graphical Abstract comparing the two types of filtration membranes and their likelihood of clogging.
The different membrane structures that lead to different levels of potential clogging. Image from https://pubs.acs.org/doi/10.1021/acs.estlett.0c00019

LFMs also have properties that provide unique advantages over commercial polymer membranes. It has the ability to self-heal after incurring damage from punctures and degradation. On top of that, an increase in membrane permeability can be achieved after LFMs undergo chemical treatments involving hydrogen peroxide and sodium hypochlorite (bleach).

Acetic Acid

Acetic acid, commonly found in vinegar, influences the permeability of microorganisms passing through the filter. It is a weak acid that lowers the pH of the environment, increasing the permeability of the bacteria membrane. This leaves them vulnerable to the now unsuitable environment, effectively killing them. Restricting the growth of bacteria inhibits the ability for biofilms to form which decreases clogging and chances of biofouling. SCOBY produces high concentrations of acetic acid, which has a key role in LFM’s ability to provide antimicrobial resistance.

Bottle of Acetic acid with a molecular model.
Acetic acid also known as ethanoic acid is a byproduct of fermentation and is commonly found in vinegar. Image from https://cdn.abcotvs.com/dip/images/10914461_072821-ktrk-shutterstock-acetic-acid-generic-img.jpg?w=1600

Plausibility for Implementation

A benefit of LFMs is that the cost of materials is inexpensive and accessible. All the materials can be easily found at a local grocery store. Although it is inexpensive to produce there are still questions about the long-term maintenance cost that need to be explored. More technological advancements need to occur in order to fully consider LFMs as a proper replacement.

However, LFMs still can have an impact on more rural communities that don’t have a fully realized water filtration system. Access to clean water is still a major issue in various communities around the world. The process of filtering water can be expensive and not readily available in many of these locations. Different engineering strategies such as LFMs must be considered to provide a less expensive alternative in order to meet the needs of communities of all socioeconomic backgrounds.

Something as mundane as a popular refreshment can contribute to our efforts in solving our clean water accessibility crisis. We must continue to use our understanding of molecular science and engineering to explore such avenues. 

See a previous IMSE blog post about developing sponges to filter out pollutants

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