Arizona State University
IN-26: Innovation C

Arizona State University seeks to achieve zero waste. Unfortunately, composting opportunities are limited in the region. Additionally, the composting facilities that do exist have different opinions about compostable food serviceware. To develop a better understanding of alternative composting methods and of compostable food serviceware, ASU partnered with NatureWorks, the City of Tempe, and DTEnvironmental to evaluate compostable food serviceware in an in-vessel composting unit. This project had the following goals: 1. Understand extent of biodegradation of a range of Ingeo PLA based compostable product formats (thermoformed goods, injection molded goods, extrusion coated paper, etc.). 2. Understand any impact such products and other composting formula ingredients have on in-vessel operation, process conditions, feedstock C/N ratio, and final in-vessel composter unit end-product. 3. Assess final in-vessel composting unit end-product to determine if a) Ingeo PLA-based compostable food serviceware are still visible and/or recognizable and b) in-vessel composting unit end-product meets State of Arizona standards for compost or if further processing is required. 4. If composting of compostable food serviceware is shown to be successful, then determine approximate operating conditions and range (time, temperature, feedstock ratio, etc.), that can be used as guidance for operators going forward, to handle a typical food/compostable food serviceware waste stream generated from food service operations. Summary of findings: Collective • Compostable food serviceware did physically break down after curing in the compost pile • The compost analyzed was healthy compost • The in-vessel unit presented a few challenges for the compostable food serviceware o Some products prematurely exited the machine o Cups had a tendency to combine with one another and ball up o Composting of food serviceware items was impacted by how they were introduced to the unit (i.e. the number introduced and how they were introduced) by the operator. For example, placing excessive stacks of cups into an in-vessel composting unit may generate issues based on the lack of separation. • Using colored SOLO Cups was not the best way to track the progress of materials running through the unit. They primarily became difficult to distinguish from other materials added for research ASU • Food waste from the kitchens at ASU was fairly clean • Food waste from ASU is melon heavy Tempe • It required more work than anticipated to operate the in-vessel but eventually got the hang of it. NatureWorks • Though not complete, the biodegradation of compostable plastic food serviceware, as measured by loss of average molecular weight (Mn), was noted during the in-vessel processing stage • The extent of the biodegradation of compostable food serviceware during the in-vessel processing stage varied among items with some items, such as plastic cups and cutlery, biodegrading more rapidly than items such as hot cup lids • Biodegradation of compostable food serviceware appeared to be almost complete after curing in the compost pile, as evidenced by the near absence of product pieces in the finished compost DTEnvironmental • The lab work corroborates previous physical observation of degradation rate of the compostable serviceware with the in-vessel system • Inclusive of a curing phase, the serviceware is largely broken down in the time it takes to meet Process to Further Reduce Pathogens (PFRP). • PFRP can be met in the drum with compostable serviceware included. At the end of the curing phase, the great majority of the serviceware was not recognizable. • Overs (materials not broken down completely) can be screened on exit from the drum and re-introduced into the beginning of the process. Detailed results were published as a Case Study in the AASHE Resources.