Plastic-to-soil Biodegradation
The Problem
Current technological solutions have been unable to stem the tide of post-consumer plastic waste, disproportionately impacting small, remote, rural and marginalized communities.
Geographic isolation, land availability, and lack of expensive infrastructure mean that common solutions such as landfilling, incineration and mechanical./chemical recycling are either short-sighted solutions or unfeasible at these scales.
Many US recycling programs have been gutted or closed altogether, at best collecting <10% of plastic waste. The vast majority of mixed, contaminated, low-value plastic waste threatens both terrestrial and aquatic ecosystems.
The Opportunity
At the same time, the carbon within these polymers could be directed towards an environmental application: building soil organic carbon in support of local regenerative agriculture.
What We’re Doing About It
To tackle the current technology gap, we have pioneered a new technology that transforms mixed plastic waste streams into a biodegradable, agriculturally valuable soil carbon amendment (Carbonmeal). This process utilizes a low cost, green catalyst to perform chemical oxidation alongside biological degradation to demonstrate non-hazardous, decentralized, distributed process suitable for small communities.
This work is funded in part by a National Science Foundation (NSF) Small Business Innovation Research (SBIR) Grant.
Technical Details
Two steps are required to breakdown the long polymer chains in commercial plastics:
1) Chemical: The Fe-fatty acid (FeFA) catalyst blended into the waste plastic through standard plastic compounding techniques catalyzes the Fenton reaction. The Fenton reaction disproportionates aqueous hydrogen peroxide (H2O2) into highly oxidizing reactive oxygen species (ROS). These strong oxidants cleave the otherwise recalcitrant polymer backbone into smaller oligomers, initiative the process of oxidation and preparing the surface for biodegradation.
2) Biological: The chemically-activated intermediate is composted with a consortium of microorganisms. These microorganisms occur naturally within commercial composting operations, and further remediate the plastic-derived organic substrate into biomass and a mixture of small and large organic acids.
Our work continues to both optimize the cost and performance of the peroxide-based chemical oxidation, as well as evolve and bioprospect for microorganisms that more efficiently biodegrade a wider range of commercial post-consumer plastics into Carbonmeal.