The misuse of disinfectants is a disaster for the environment. Compounds containing chlorine, such as bleach, can produce potentially dangerous byproducts by reacting with other chemicals. Other potential greener disinfectants are based on phenol or its chemical relatives, but they can be expensive and energy-intensive to create.
Phenolic structures, however, abound in wood, as do some of the large branched molecules that make up the cell walls of plants. This is why the environmental engineer Shicheng Zhang of Fudan University in Shanghai and his colleagues questioned whether sawdust waste could provide a greener source of antimicrobial compounds.
Water and sawdust for a terrific disinfectant
The researchers cooked mixtures of water and sawdust for an hour under pressure, filtered them and examined the results. Then the team tested the sawdust mixtures for their ability to kill it staphylococcus epidermis, a skin microbe that can cause infections in immunocompromised individuals, and E. coli, a bacterium that can cause foodborne illness. Depending on the concentration, this disinfectant can kill more than 99% of microbes, the team reported Proceedings of January 18 of the National Academy of Sciences .
Sawdust disinfectant was equally successful in inactivating anthrax and influenza viruses, the study says.. It is also highly effective against spores, dormant forms of bacteria that can be difficult to kill. The tests have so far shown efficacy on the Bacillus subtilis (which, however, is already harmless in its own right).
Chemical analysis of this sort of “sawdust soup” revealed high quantities of phenolic compounds. It is likely that the wood's molecular chains are disrupted during pressure cooking, releasing antimicrobial phenolic molecules.
Under the microscope, the scientists saw that their disinfectant damaged the cell walls of E. E. coli coli e S. epidermis. Phenolic compounds can also damage the proteins and genetic material of bacteria and viruses, Zhang says.
More sustainable than that.
