Biodegradable Pots - Replacing agricultural and horticultural plastics on campus

Estimated Amount to be requested from the CSF: $70,000

Letter of Intent:


While University of Washington agriculture groups are among the greenest operations on campus, currently all horticulture and agriculture groups are using plastic pots for their needs. With the technology, expertise, and additional resources already available in the UW Paper and Bioresource Science Center, there is a clear opportunity for green, biodegradable pots to be produced on campus, thereby replacing all need for the purchase and disposal of thousands of plastic pots. Our ultimate goal is to provide the campus with sustainable alternatives to disposable plastics across campus groups, research facilities, and classrooms wherever possible.

Environmental Impact

Current campus use: While groups across campus are currently washing and reusing their plastics, this can be water-intensive and often includes bleaching the pots, creating hazardous run-off. The energy and petroleum intensive production of these plastic nursery pots, as well as the potential for them to end up in landfill to consider. To combat the drawbacks of using petroleum-based plastics, this project proposes the most sustainable product possible for use across campus.

Proposed solution: The biodegradable pots will be planted directly into the soil leading to zero waste products at end-use. Additionally, pulp fiber pots will be cut with up to 60% brewers’ spent grain. This remedies a growing problem of wasted spent grain that has arrived with the popularity of breweries in Washington State. One of the most unique attributes of these pots is the application of a sustainable re-use for this grain that will provide nutrients back to the soil. Furthermore, the remaining structure will be molded of barley or wheat straw as an economically feasible raw-material.

Utilizing another waste product from the Paper and Bioresource Lab, fertilizer can be implemented via spraying a ‘black liquor’ solution on the inside of the pots. Using black liquor from already-existing sulfite pulping operations can add sulfur and lower pH to amend the soils, as well as aid the structural integrity of the pots. Black liquor is made of residual sugars, lignin and dissolved solids, thus adding only organic material back to the soil. In total, carbon from these waste materials and black liquor are sequestered from the biomass into the ground, resulting in a carbon-neutral process from our estimates.

Student Leadership and Involvement

This project is overseen by a core of five Bioresource Science and Engineering juniors and seniors as well as students from the UW Society for Ecological Restoration (UW-SER), each specializing in different areas. With support from the UW Paper and Bioresource Lab, each member of the team has a specialty in analytics, chemical composition of the pots, machinery, molding technologies, or black liquor fertilizer implementation.

In addition, part of this grant covers a new molding system which can provide UW students a chance to apply classroom concepts in the lab, experiencing a production line from starting bio materials to end-product. This machinery can specifically be used for Bioresource Science and Engineering curriculum, providing students with hands-on experience with pilot-scale industry machinery.

Education, Outreach, & Behavior Change

This interdisciplinary project currently involves a close partnership across majors and campus groups. Currently, our closest partnership is with UW’s Society for Ecological Restoration. By servicing UW SER alone, we will replace the need for approximately 500 seedling containers per year, among others. With the help of this grant we hope to replace thousands more across campus. Once this product can be produced to scale, we can provide our biodegradable pots to any group on campus who would be interested in cutting plastics use and fertilizer costs. Ultimately, our goal is to see all plastics use by agriculture and horticulture groups replaced by our products, adding another element to UW’s reputation as a green campus.

Feasibility, Accountability, & Sustainability

This team of students is competent in their respective specialties, has experience in the Paper and Bioresource Labs as well as industry applicability. This team will be overseeing the full implementation of the project throughout, once these students graduate, new Bioresource Science and Engineering students will be fully equipped to continue production.

With the pilot-scale equipment, it will also be possible and necessary to create several molds and fertilizer options for various applications to eliminate all plastic pots on campus. Our proposed process for production is outlined in Figure 1 below.


Figure 1. Biodegradable products production, machine process

Budget Estimate

While we have the technology, information, and research to begin production, the current methodology is primitive, and capital is needed to increase and streamline production to extend reach across campus. While we have extra tanks, pumps and other generics to put towards this endeavor, in total, we are requesting $90,000 to complete this project, the details of which are outlined below.


  • $60,000 automated mold equipment (online estimate), Figure 1 displays the main units considered in this cost.
  • $10,000 Infrastructure (piping, wiring)
  • $8,000-$10,000 molds for several pot sizes (designed in collaboration with UW SER)
  • $2,000 sprayer for  black liquor coating


  • $2,000 start-up costs
  • $1,000-$3,000 chemicals - release agent, black liquor, shipping
  • $1,000 raw materials, shipping
  • $2,000 equipment spares (pumps, seals, extras)
Primary Contact First & Last Name: Kaitlin Tighe