Plastic-to-Soil

Secure, Sustainable, Self-sufficient Island Communities

The Problem

 

Current technological solutions have been unable to stem the tide, 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.

 

See our full infographic and white paper on The Flow of Waste and Carbon in Hawai'i to learn more.

What we're doing about it

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To tackle the current technology gap, we have pioneered a new technology termed Pseudo-Intramolecular Controlled Oxidation (PICO) capable of transforming mixed plastic waste streams into a biodegradable, agriculturally valuable soil carbon amendment (Carbonmeal). In a process analogous to composting, this technology utilizes a low cost, green catalyst based on iron fatty acids (FeFA), and the non-hazardous, decentralized, distributed manufacturing process makes it suitable for small communities.

This work is funded in part by a 2021 National Science Foundation (NSF) Small Business Innovation Research (SBIR) Grant.

Technical Details

 

The PICO system comprises of two steps:

1) Compounding - The FeFA catalyst is thermomechanically blended into granulated plastic waste utilizing existing, low-cost decentralized plastic recycling technologies, such as the extrusion systems pioneered by Precious Plastic.  Inclusion of water, or other similar non-toxic blowing agents, creates a porous pellet with high surface area optimized for the oxidation-digestion reaction.

2) Oxidation-Digestion - The FeFA-activated plastic pellets are digested in safe, non-hazardous concentrations of H2O2. The imbedded, pseudo-intramolecular Fe-catalyst initiates the Fenton oxidation reaction: disproportionation into highly reactive, transient reactive oxygen species (ROS). This ROS cleaves and oxidizes a wide range of polymers into long-chain, insoluble carboxylates, simultaneously remediating contaminants and plastic additives to benign species. Imbedding the catalyst directly into the plastic ensures efficient use of H2O2 to lower cost and accelerate reaction times.

Simple coagulation/precipitation by acidification or addition of Ca or Mg cations produces a mixture of biodegradable long-chain fatty acids we collectively term Carbonmeal, easily separated by simple filtration.

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