For some reason, everybody seems to have got interested in keeping things clean lately. The COVID-19 pandemic saw antiviral hand gels sold out across the world while news reports circulated of people drinking bleach or bathing in disinfectant in an effort to keep the virus at bay.
The problem with all that – apart from the massive uptick in calls to poison control (seriously people, don’t drink bleach) – is that these disinfectant measures all come with a cost. Bleach, for instance, is one of the most hazardous compounds out there in terms of environmental effects, and without careful management can wipe out whole populations of aquatic life. Other sanitizers rely on isopropyl alcohol, which is only produced in a handful of places and has an outsized carbon footprint. There’s another kind of disinfectant, called phenolics, which may have better environmental credentials than the others, but are expensive and energy-intensive to produce.
That’s one motivation behind a new study, published this week in the journal PNAS, which aimed to find an alternative, sustainable disinfectant. The answer: sawdust.
“Biomass is widely available and renewable, and has typical multi-antibacterial structures, such as phenols and ketones,” the study points out. “In this study, a renewable disinfectant was developed from biomass and its effectiveness against highly pathogenic microorganisms was examined. The study demonstrates that effective use of biomass has the potential to support the biosafety of human environments with greater sustainability.”
Basically, the researchers noticed, phenolic structures already exist in nature – specifically, in the molecules of plant cell walls. By mixing sawdust with water under high pressure, the team created a liquid which they tested against viruses including E. coli, Staphylococcus epidermis, anthrax, and influenza A – all of which fell to the sawdust mixture.
“The inactivation rates of H1N1 (mask and quartz sand as carriers), H5N1, and H7N9 [flu viruses] were all 99.99% … and that of B. anthracis (quartz sand as carrier) was 99.49%,” the paper reports. “In addition, the inactivation rate of Bacillus subtilis var. niger spores (a typical challenge bacterium used to evaluate the disinfection effect) was 99.99%, indicating that the disinfection function of bioliquid had a broad spectrum.”
What’s more, the liquid was “safe in case people or animals unwittingly touch it,” the researchers noted, and cheap as well, costing less than 5 cents per kilogram to produce – that’s two hundred times less expensive than even some of the most economical hand sanitizers. And since the team found that many different types of sawdust can be used to create the liquid, they estimate a production capacity of a massive 113.02 million tons, which they point out is “beneficial for large-scale production, due to the abundance and low cost of renewable materials compared to those of the currently available commercial disinfectants.”
As the world continues to urbanize, industrialize, and hurtle towards a climate apocalypse, the need for biosafety – that is, keeping our environments relatively free from pathogens – is only getting more important. But with this new study, it is clear that the development and production of disinfecting agents doesn’t need to come with the high price we’re used to paying right now.
“Overall, the developed bioliquid is a good candidate for the prevention of an outbreak and for establishing better biosafety of human environments,” the authors write. “In addition, this bioliquid has a broad spectrum of action and a low cost, as it is obtained from renewable biomass, which is advantageous for large-scale applications.”
“Given the potential demonstrated in this study, the separation method for the enrichment of low-molecular-weight and low-polarity compounds should be more broadly studied to promote the commercial application of bioliquid,” they conclude.