Newswise — Researchers at Iowa State University and their partners will create a system that converts wastes generated by military expeditionary forces into food. The technology could vastly improve military logistics and may have wider application to produce food and reduce plastic wastes. 

The Defense Advanced Research Projects Agency (DARPA) has awarded a Phase I cooperative agreement for $2.7 million that could entail up to $7.8 million over the course of the project. Partners include the University of Delaware, Sandia National Laboratories, and the American Institute of Chemical Engineering (AIChE)/RAPID Institute. 

The system, dubbed Novel Oxo-degradation to Macronutrients for Austere Deployments (NOMAD), aims to convert plastic wastes into fatty alcohols and fatty acids, and paper wastes into sugars to be bioprocessed into single cell biomass rich in proteins and vitamins. Familiar examples of single cell proteins are nutritional yeast and Vegemite. NOMAD will be a fully integrated system that conforms to specific size, weight, and power requirements to enable transportation, deployment, and extraction by military expeditionary forces. 

Turning paper into sugars builds on previous biomass pyrolysis research at Iowa State, while the conversion of plastics into fatty compounds draws inspiration from the natural process of plastics degradation in the environment. 

“When exposed to heat or ultraviolet light in the presence of oxygen, plastics convert to oxygenated compounds that can be consumed by microorganisms – plastics are, in fact, bio-degradable, but the process is very slow, as evidenced by the accumulation of plastic wastes in the environment,” explains Dr. Robert Brown of Iowa State, the project’s principal investigator, Anson Marston Distinguished Professor in Engineering and the Gary and Donna Hoover Chair in Mechanical Engineering. 

“We can dramatically increase oxo-degradation of plastics to fatty compounds by raising the temperature a few hundred degrees Fahrenheit. The cooled product is used to grow yeast or bacteria into single cell proteins suitable as food,” Brown said. 

Food from wastes, especially plastics, has many potential benefits. For military expeditionary forces, the technology could potentially convert every pound of packaging and similar expendable supplies into four ounces of nutritionally-balanced high-protein nourishment for soldiers. Such a system would improve the military logistics resiliency and extend military missions. 

Beyond the military, the conversion of waste into food would go a long way toward solving looming problems of plastic disposal and ensuring a viable global food chain. It might also be possible to extend the technology to production of chemicals currently produced from petroleum, reducing the extraction rate for this fossil resource. 

NOMAD includes innovations in four processes needed to convert waste into food: release, breakdown, build-up, and recovery. For the release phase, waste streams of polyethylene terephthalate (PET), high density polyethylene (HDPE) and low density polyethylene (LDPE) plastics and paper are ground to peppercorn-sized particles and loaded into a thermal reactor. In this step, heat and oxygen break the plastics into fatty molecules and wastepaper into sugars. The team will build on Iowa State’s advances in autothermal pyrolysis to self-heat the reactor. 

Plastics and wastepaper, however, contain virtually none of the macro-elements (phosphorous, potassium and nitrogen), micro-elements (for example, trace metals) or amino acids required for microbial growth. So, the NOMAD project will aim to harvest these nutrients from the local environment, such as local water sources and purified nitrogenous waste. A key component of the design is the use of microalgae to harvest nitrogen, a key component protein, from the air.

One of the key challenges in bioprocessing is product recovery, which is particularly problematic for troops in the field. The project avoids this problem by exploiting the natural tendency of many kinds of microorganisms to spontaneously clump and settle out from suspension at the end of the process, allowing recovery as a slurry from the bottom of the bioreactor. 

Later phases of the project include development of procedures for disinfection of the equipment and integration of the various systems. 

In addition to Brown, the Iowa State team includes Laura Jarboe, a professor of chemical and biological engineering, and Zhiyou Wen, a professor of food science and human nutrition and director of the Center for Crops Utilization Research. The University of Delaware effort is led by Mark Blenner, professor of chemical engineering. The Sandia team includes Anthe George, scientific lead, Biomass Pretreatment and Process Development. The AIChE/RAPID Institute is represented by Fereshteh Farzad, principle technical program manager at the RAPID Manufacturing Institute.

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