Grantee Research Project Results

Final Report: Upcycling Food Waste into Bacterial nanocellulose to Create High-Performance Dimensional Wood

EPA Contract Number: 68HERC25C0019
Title: Upcycling Food Waste into Bacterial nanocellulose to Create High-Performance Dimensional Wood
Investigators: Tavas, Gabriel E
Small Business: Symmetry Wood, PBC
EPA Contact: Richards, April
Phase: I
Project Period: December 16, 2024 through June 15, 2025
Project Amount: $100,000
RFA: Small Business Innovation Research (SBIR) - Phase I (2025) RFA Text |  Recipients Lists
Research Category: Small Business Innovation Research (SBIR)

Description:

Symmetry Wood’s Phase I SBIR project sponsored by the EPA explored the potential of bacterial nanocellulose to valorize organic wastes, converting them into entirely biobased, tree-free Pyrus™ hardwood. Specifically, it involved growing nanocellulose from various types of beer waste as well as converting already-grown nanocellulose waste from kombucha breweries into wood samples suitable for materials characterization testing. By experimenting with both nanocellulose growth and nanocellulose-to-wood processing, Symmetry Wood’s team gained practical insights for scaling its production. Additionally, Pyrus™ underwent unprecedented materials characterization, which enabled comparison to endangered tropical hardwoods and other materials.

Summary/Accomplishments (Outputs/Outcomes):

Symmetry Wood confirmed that beer waste is a viable option for generating bacterial nanocellulose, although multiple prerequisites must be met, especially beyond the laboratory scale. Moreover, certain types of beer waste are easier to use than others. During the final trial of nanocellulose growth, close to 90% of the sugar content of 30 gallons of dissolved beer waste was consumed by the nanocellulose fermentation process over 28 days. Assuming typical brewery waste characteristics, aerobic bacterial metabolism, and standard bioprocessing conversion factors, there was likely a 70-85% reduction in chemical oxygen demand (COD) and a 20-30% reduction in total dissolved solids (TDS) over the 28 days. Approximately 60 grams of nanocellulose was collected from the trial. The Symmetry team also processed bacterial nanocellulose from kombucha with new equipment to create the thickest, solid Pyrus™ samples to date. 23 samples of different dimensions were subjected to three-point bending, tensile, and compression tests which had already been conducted on tree-derived wood in another scientific study. Flexural yield stress of Pyrus™ ranged from 73-114 MPa, close to twice that reported for natural wood domestic to the United States, such as basswood, oak, poplar, western red cedar, and eastern white pine. The tensile stress reached 49.56 MPa, greater than even a single layer of densified tree-derived wood. Lastly, compressive strength averaged 203 MPa, far higher than that of any natural or densified tree-based wood (and several times that of concrete).

Conclusions:

Beer waste can certainly contribute to the scaling of Pyrus™ production, allowing Symmetry Wood to produce more nanocellulose without relying on kombucha breweries, and reducing the risk of organic pollution from the beer industry. However, other types of organic waste would probably be easier to use first, both for biochemical and logistical reasons. As well, the largest beer breweries may be looking for Symmetry Wood to achieve a greater level of production, along with a greater volume of wastes utilized, before they would seriously consider a partnership. Craft beer breweries and kombucha companies have proven more readily supportive and accommodating. The mechanical property testing, conducted as part of this SBIR project, confirmed that, even in its early stage of development, Pyrus™ has isotropic mechanical properties that consistently match or surpass those of the most common U.S. domestic woods. Its compression strength surpassed that of all tree-derived woods, as well as that of concrete. Provided it becomes cost effective, Pyrus™ has the potential to replace some of the $1.6 billion worth of tropical hardwood imported annually into the U.S. for manufacturing of musical instruments, flooring, decking, furniture, and more.

Commercialization:

There is enough nanocellulose waste from Symmetry’s partner in the kombucha industry and customer interest from major guitar manufacturers to enable the initial commercialization of Pyrus™. In-house organic waste fermentation is not necessary to make the first $1 million in sales. The near-term priority is to enhance the efficiency, automation, and productivity of Pyrus™ manufacturing. The use of other types of organic waste will only become essential once sales of Pyrus™ approach either 50% of US stringed instrument fretboards and fretboard-bridge combinations, or a similar volume of flooring. At that point, Symmetry will have gathered the resources and partnerships necessary to start commercial fermentation.