Federal Agency Tries Biodegradables

From BioCycle
Journal of Composting &Organics Recycling
March 2001, Page 80

TARGETING CAFETERIA STREAM
FEDERAL AGENCY TRIES BIODEGRADABLES
U.S. Department of the Interior pilot project diverts food residuals and biodegradable food service ware from employee cafeteria to composting.
Jeff Olawski

IN 1989, then Secretary of the Interior Manuel Lujan, Jr. — wanting to set an example for environmental stewardship — banned the use of polystyrene products in the department’s Washington D.C. headquarters’ cafeteria. A search for replacements revealed that paper products did not perform up to expectations. The cups were too hot to hold comfortably and often leaked, and the plates were too flimsy. With no substitute product in sight, the department’s food service contractor came up with an alternative: a polystyrene recycling project. The project was an apparent success until it was discovered — after five years of operation — that the materials were not being recycled. Instead, the recycling contractor had been sending the polystyrene to a landfill.

Caught in a crisis, the Department of the Interior (DOI) had to find another alternative, one that would satisfy a diverse set of requirements. The food service contractor demanded that the price be competitive, and DOI employees insisted that the product work properly. Above all was DOI’s requirement that whatever the alternative, it had to be better for the environment or else it wouldn’t be worth making the change.

The DOI eventually found EarthShell Packaging, which is made from potato starch, limestone, water and a small amount of recycled paper fiber. In addition to being biodegradable, the product was manufactured in a clean, energy efficient manner. Although the product was still in the research and development phase, the manufacturer — EarthShell Corporation of Baltimore, Maryland — was nonetheless interested in partnering with DOI to conduct “real world” testing of its then fledgling product line in order to move it to market. Besides offering a short-term solution to the polystyrene problem, DOI recognized the long-term impact biodegradable food service ware could have if combined with composting. The department employs 70,000 nationwide and has millions of visitors each year to the national parks and other facilities it manages. With that in mind, a pilot composting project was designed to explore the feasibility of cocomposting biodegradable food service ware and organics and to serve as a model for food residual management that could be replicated throughout all DOI facilities nationwide.

LAUNCHING THE PROJECT

The composting project — involving the DOI, U.S. Department of Agriculture (USDA), U.S. Environmental Protection Agency (EPA) and EarthShell — kicked off on Earth Day 1999 and ran for a year. Food service workers at DOI’s Washington D.C. headquarters cafeteria switched from the polystyrene plates and bowls to biodegradables. An educational campaign was launched that informed patrons of the program. Source separation areas in the cafeteria were redesigned so that patrons easily could divert biodegradable food service ware, unbleached recycled content paper napkins, any leftover organics and the 100 percent recycled content carry-out trays into specially marked containers lined with biodegradable trash bags. Once or twice a week, the DOI trucked the bagged material to USDA’s Agricultural Research Center in Beltsville, Maryland, where Patricia Millner and colleagues tested different composting methods.

Millner, a USDA microbiologist, added grass clippings and partially decomposed fall leaves to the organics and food service ware in 3.5:2:1 proportions in order to achieve a C:N ratio of 32:1. Several approaches were used to reduce particle sizes and to improve the mix uniformity prior to composting. Moistening followed by pulverization (achieved by running over the mix with a front-end loader) worked the best and was as rapid as grinding. The mixtures were composted using windrows, static piles in bins (turned weekly with a front-end loader) and an Earth Tub in-vessel system. These were the methods that DOI most likely would consider in any future expansion of the pilot, especially if the food residuals were to be incorporated into an existing yard trimmings composting operation.

The quickest and most consistent results were obtained from the in-vessel container, which has a mixing auger. Only small traces of the biodegradable plates, bowls and bags could be identified after four weeks. Windrows and static piles were less efficient in decomposing the shredded biodegradables as the polymer films’ lighter weight made them susceptible to separating out during turning operations. As a result, they concentrated outside the piles rather than being uniformly distributed within. By six months, virtually all of traces of the biodegradables were gone in all the composts — on a gravimetric basis they represented a very small percentage (<0.5%) of the composts’ total dry weight.

According to Millner, peak self-heating ceased after approximately 12 weeks, although some additional decomposition occurred during the curing phase. At the six- month mark, mature compost from all three methods was screened using a standard three-eighth-inch trommel, and the final product did not contain any visibly recognizable traces of the food service ware. Preliminary results indicate that the compost is high quality. Millner used it to grow cucumbers and found they did as well as those grown in commercial potting mixes.

LESSONS LEARNED

The largest problem encountered during the pilot project was nonbiodegradable product contamination, which occurred in the cafeteria source separation area. It turned out that DOI cafeteria patrons thought that all of the food service ware was biodegradable; however, only the six-inch bowls and nine-inch plates were EarthShell products. The remaining service ware such as cups were still polystyrene and the eating utensils were conventional plastic. As a result, nonbiodegradables became commingled with the biodegradables, with plastic forks, knives, spoons and plastic wrap proving to be the major contaminants. This was a major problem that required personnel at USDA’s Beltsville Composting Research Facility to hand sort prior to composting.

Although the year-long composting project ended in May, 2000, the department would like to expand it into a full-scale operation that would include the headquarters’ cafeteria prep waste. To address the contamination issue, patron education efforts would be stepped up and the use of biodegradable service ware maximized. However, project team leader Ken Naser notes that DOI has yet to locate a local commercial composting facility that will accept food residuals. Nonetheless, the department continues to look for suitable facilities and composting partners in the Washington, D.C. metro area, and is even considering operating its own facility if suitable land can be found. Meanwhile, EarthShell Corporation continues to supply the department’s cafeteria with biodegradable plates and bowls. In January, the cafeteria started using and testing the company’s latest product — a clamshell sandwich container which, according to Naser, insulates well, is rigid enough to protect its contents, and opens and closes without problems. — J.O.

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