Commercial food waste from restaurants and grocery stores by Ty Newell, Elizabeth Markstahler and Matthew Snyder Ty Newell is an associate professor of mechanical engineering at the University of Illinois and is president of the Community Recycling Center’s board. Elizabeth Markstahler is director of operations at the Community Recycling Center. Matthew Snyder is executive director of the Community Recycling Center andìs a research engineer at the U.S. Army Construction Engineering Laboratory in Champaign, Illinois. The Community Recycling Center is a not-for-profit corporation located in Champaign-Urbana, Illinois and was the National Recycling Coalition “Recycling Center of the Year” awardee in 1990.

A study concludes that starting a food waste collection program can significantly reduce a community’s waste stream.

56 Resource Recycling

February 1993

Food waste is attracting a lot of interest because it is one of the largest waste generation categories. Both residential and commercial waste stream investigations cite food waste as representing between 10 percent and 15 percent of all waste. When collected in a source-separated manner, food waste can be processed into a high quality compost material. Collection and processing of food waste is relatively new compared to the “wellestablished” field of curbside collection of containers and newspapers. To gain experience in the food waste area, the Illinois Department of Energy and Natural Resources supported the Community Recycling Center’s efforts to audit food and other waste materials from seven commercial participants. The reason for concentrating on commercially generated food waste is because a relatively small number of businesses in the commercial sector (food stores and restaurants) generate most of the material. In ChampaignUrbana, with a population of 100,000, for example, it is estimated that the residential sector will generate 6,000 to 7,000 tons per year of food waste material, compared to approximately 5,000 tons per year estimated for the commercial sector. However, material from the residential sector must be collected from over 30,000 residential households, compared to only 350 commercial business in the food-related sector (260 restaurants, 90 food stores). Commercial businesses tend to have relatively well-structured waste generation systems (e.g., shipping/receiving, produce cleaning/washing and dishwashing areas). Overall, the commercial sector is a logical place to phase in food waste collection programs with subsequent extension to the residential community. The study had severa1 goals. First, examine the waste generation rates.

Second, conduct waste audits in a manner that simulates a real food waste collection program. Third, examine the characteristics of each participant and compare similar and dissimilar features. Fourth, develop methods for estimating waste generation rates from restaurants and food stores. And finally, assess the collection costs of a commercial food waste program.

CollectiorVauditing methods Seven businesses participated in the food waste study. Waste was collected from each participant for two weeks. Four restaurants, two grocery stores and a University of Illinois sorority gave a broad range of waste generation rates and composition. Although the sampling size for the program was small, enough information was gathered to gain the confidente required for initiating a food waste collection system. One word of caution: While a larger sampling size would improve the statistical average values of the study, the nature of the waste stream is one in which the deviations are real and must be dealt with individually. The auditing procedure consisted of collecting containers designated for each material category of interest. Collection containers were taken to the Community Recycling Center’s processing facility and weighed. No dumping/sorting activities were used to further separate and categorize material, but comments were written on the visual condition of the material. (Dumping/sorting of material would be considered a waste transfer activity and would require special permitting.) General waste, food waste and corrugated containers were usually collected in two-cubic-yard roll-off containers. Barrels (55-gallon) were used to collect glass, plastic, paper and metal can materials following CRC’s standard commercial material collection practices. Volume estimates were made by visual inspection. Dumpster estimates were re-

Board of Trade. According to Mike Walsh, advisory economist in the Economic Analysis and Planning Department of the Chicago Board of Trade, the Board of Trade may some day operate a commodities exchange for recyclable products, in much the same way as it does now for other commodities. Walsh said the Board of Trade has met with representatives of industry and the public sector to discuss the needs and interests of the recycling markets. “There is a lot of interest, but we need to further explore whether that interest can be turned into participation in a market,” Walsh says. The Board of Trade was formed in 1848 as a centralized marketplace for grain. Today its largest volume market is in financia1 futures and options on such commodíties as government treasury bonds. If the Board of Trade decides to add recyclable goods to its product list, the first step might be to set up a cash market. The Board of Trade would bring buyers and sellers together to market quantities of used newspapers or glass, for example. Walsh said that some day the Board of Trade might offer a futures market for recyclable products, where buyers could lock in future transaction prices. The advantages of a futures market would be standardized contracts and stabilized prices. For the present, however, the emphasis is on exploring a cash market. Recycling experts agree that, to a large degree, the future of the industry will depend on the success of such innovative marketing programs. Increased and stable demand, they aver, is the only way to meet the challenges of increased supply. RR

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n Figure 1 -

Waste percentage categories for all study participants

7

%

m

2

3

Y

8

of Source: Ty Newell, Elizabeth Markstahler and Matthew Sn der, An Investigation Commerclaly Generated Food Wasfe and Recycla tYle MateriaIs, Community Recycling Center, December 1992. \

corded as fractions of a bin. Small volumes were sometimes recorded by the size of a bag (e.g., one bag = 35 gallons) in a waste bin. “Volume” is a difficult quantity to assess because it is dependent on compaction by personnel at the business. For example, general waste bins were frequently filled because a significant volume of material consisted of plastic film and other types of fluffy material that would expand to the size of the bin. Food waste generally showed more consistency because of its naturally dense condition.

containers. Restaurants such as Bob Evans and Pizza Hut had smaller fractions of recyclable containers compared with Katsina’s and Minneci’s because beverages were served in glasses from soda dispensers rather than bottles. The Delta Gamma Sorority had the largest “garbage” fraction because of the other n Figure 2 -

non-food related waste generated in a residence hall environmet?. Waste generation rates ranged widely. Jerry’s IGA food store on Philo Road generated 30,000 pounds of waste over a two-week period compared to Jerry’s IGA on Kirby Avenue with 14,000 pounds of waste. Table 1 contains the overall waste generation amounts for each business. Restaurant waste generation varied over a wider range from Minneci’s at the low end to Bob Evans at the high end. Combining waste generation and volume amounts allows waste densities to be determined. Figures 2 and 3 are plots of garbage weight versus volume and food waste weight versus volume, respectively. The average density of garbage was found to be 120 pounds per cubic yard. A line representing 120 pounds per cubic yard density is shown on Figure 2, with two surrounding lines showing plu.s/minus 10 percent deviations. The Bob Evans Restaurant data point in Figure 2 has a circle around it. Garbage density for Bob Evans is almost three times the garbage density found in any of the other audits. The primary reason is due to food waste in the garbage bins. The Bob Evans Restaurant is a very high volume restaurant located at a busy shopping center and interstate highway exit location. Disposing food waste into the correct container during peak periods was difficult. Discussion with restaurant management indicated that color-coding collection containers

Garbage weight versus collection volume

5000

Waste category results The primary waste categories studied were food waste, recyclables and “garbage” (materials without a developed collection and/or processing system locally available, such as miscellaneous plastic film packaging). Figure 1 is a chart that shows waste category percentages from each of the study’s participants. The two grocery stores were dominated by corrugated containers and food waste. Recyclable containers (glass, metal cans, plastic containers and Office paper) were a small fraction of the material composition. The restaurants were dominated by food waste with garbage as the second largest material, followed by corrugated

56 Resource Recycling

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1993

0 ’ 0

I 5

I 10

I 15

I 20

I 25

Volume (cubic yards) @

= Bob Evans Restaurant

Source: Ty Newell, Elizabeth Marketahler and Matthew Sn der, An Investigafion of Commerclally Generafed Food Waste and Recycla l le Materials, Community Recycling Center, December 1992. L

30

H Figure 3 -

and streamlining the system as much as possible would help improve the system. Also, the two-week audit period was relatively brief for properly training restaurant employees (approximately 70 employees). No attempts were made to separate food waste found in garbage bins (as well as occasional garbage found in food waste bins). An interesting feature of the Bob Evans Restaurant is its relatively low 0.8 pounds of waste generated per meal. Figure 3 shows relatively good agreement among all participants with the exception of Pizza Hut (for which the data point has a circle around it in Figure 3), and the Delta Gamma Sorority (marked by a square surrounding the data point). Pizza Hut was found to have large uncooked dough amounts (one day had 570 pounds of food, primarily dough, with a density of 850 pounds per cubic yard). Pizzerias can keep dough only for approximately 17 hours before throwing it out. Casual examination of roll-off containers from other pizzerias showed uncooked dough to be a relatively common waste material. The Delta Gamma Sorority had a food density somewhat less

Food waste weight versus collected volume

5000 4000 35 Y0 3000 a> in g 2000 B

0

LL 1000 0 8 6 4 Volume (cubic yards)

0 @ = Pizza Hut.

q

= Delta Gamma Sorotity

Source: Ty Newell! Elizabeth Markstahler and Matthew Sn der, An Invesfigafion of Commeroally Generated Food Waste and Recycla t le Materials, Community Recycling Center, December 1992.

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rants participants. A square has been placed around the sorority data point. Other Cardboard Garbage Food Location Garbage plus food waste tends to be 240 6,265 2,927 4,470 Jerry’s IGA @ Kirby 3.85 times larger than corrugated con909 ll ,923 9,290 Jerry’s IGA @ Philo 8,240 tainer generation rates. A line on Figure 4 98 1,100 4,638 4,870 Bob Evans Restaurant shows this relation, with two lines repre390 210 1,800 1,473 Katsina’s Restaurant senting plus/minus 10 percent deviations 113 255 Minneci’s Ristorante 490 680 surrounding this line. The only major de61 525 Pizza Hut 680 1,360 viation in Figure 4 is the circled data point 96 300 1.084 623 Delta Gamma Sorority representing Bob Evans Restaurant. There are two posible reasons for the (1) Pounds collected over a two-week audit period. First, some cardboard was I deviation. found in the garbage roll-off container. Source: Ty Newell, Elizabeth Markstahler and Matthew Snyder, An Investigation of Commercially Generated Food Waste and Recyclable Materials, Community Recycling Center, DeBetter separation techniques would tend cember 1992. to lower the data point as well as move it to the riaht in closer aareement with the than 450 pounds per cubic yard. (The for restaurants and grocery stores, re- other data. The overallcorrection due to sorority also had approximately 600 spectively. The basis of Figure 4 and 5 is this would not be sufficient to bring data pounds of food waste from a Halloween that most material delivered to the into agreement with the other sites. pumpkin carving activity that have not businesses is delivered in corrugated Another explanation is that the Bob been included in the Table 1 information.) containers. Evans organization (almost 300 restauThe value of the relations is that an al- rants) is able to ship material with more ternate method for waste estimation can efficient packaging. Another feature of be formulated for businesses that already the plot in Figure 4 is the variation of food Other characteristics Detailed descriptions of the audits and collect (and know) their corrugated con- and garbage data points. Individually, the participants can be found in the proj- tainer waste stream. Grocery stores neither food nor garbage correlate well ect’s final report, An Investigation of would be primary candidates for this with cardboard; however, when comCommercially Generated Food Waste method of estimation because they fre- bined, the correlation agreement is quite quently have corrugated container baling reasonable. and Recyclable MateriaIs, December 1992. Severa1 other parameters‘ have systems in place. Figure 5 shows a similar relationship been examined in order to find features Figure 4 includes data from the Delta between food plus garbage wastes for that can help explain waste generation Gamma Sorority as well as all restau- grocery stores. Only two data points are characteristics. For example, restaurants showed a large variation in waste generH Figure 4 - Restaurant waste generation as a function of ation per employee (4.6 pounds to 7.8 corrugated container generation pounds waste per day per employee), 10000 waste generation per meal (0.8 to 2.2 pounds waste per meal) and waste per seating capacity (0.9 pounds to 4.8 $!j+8000 pounds of waste per day per seat). 5 G + F = 3.85*CC (1) The two grocery stores showed a range of waste generation per floor area -5 6000 from 52 pounds per 1,000 square feet per I .-cn day to 62 pounds per 1,000 square feet g 4000 per day. The smaller grocery store has the higher waste production per floor Q, area. The smaller store is representative gj 2000 of older style grocery stores while the larger store is very modern with specialty areas (gourmet shop, florist, bakery, 0 snack bar, etc.) that tend to have lower 1000 600 800 0 200 400 material volumes per floor area. The grocery stores have similar waste generCorrugated container weight (pounds) ation per employee - 25 pounds per emG + F = Garbage plus food. ployee per day. CC = Corrugated containers. An interesting characteristic of the @ Delta Gamma Sorority. study participants is an apparent relation between the amount of waste (food and @= Bob Evans Restaurant. garbage) generated and the amount of (1) Ga~;~a,“us food is approximately 3.85 times the generation rate of corrugated corrugated containers collected. Grocery stores and restaurants showed different Source: Ty Newell, Elizabeth Markstahler and Matthew Snyder, An Invesfigafion of wasteicorrugated container correlations. Commercially Generated Food Waste and Recyclable MateriaIs, Community Figures 4 and 5 show the relation beRecycling Center, December 1992. tween waste and corrugated containers

n Table 1 -

Waste audit weight results (1)

60 Flesource Recycling

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1993

’

available from the study. Both data points do seem in reasonable agreement (relative to the plus/minus 10 percent deviation lines) and indicate that food plus garbage waste generation is approximately 1.39 times the corrugated containers generation rate.

n Figure 5 -

Grocery store waste generation as a function of corrugated container generation

G + F = 1.39*CC(l)

Commercial food waste collection costs An examination of the cost impact of a source-separated commercial food waste program has been evaluated using computer software, kNOw WASTE Collector, developed by The Advent Corporation. The simulation examined the impact of a food waste collection program on a community of 100,000 residents over a range of commercial participation from 0 to 100 percent. Four scenarios were examined. First, a collection system was assumed in which the collection frequency for the food waste remains the same as in the original mixed waste collection system. The second case assumed more frequent collection of food waste (approximately three times more may occur at some restaurants and food stores in which odor buildup may be a concern). Cases one and two assumed that travel to the garbage disposal site and to a food waste processing site (e.g., a composting facility) was the same. Cases three and four are the same as cases one and two except for a longer travel distance used for garbage disposal compared to food waste disposal. This case represents communities that do not have local landfil1 access but that develop a food waste processing system locally. The travel time to and from a local facility has been assumed to be 30 minutes and the travel time to and from a distant facility has been assumed to be 1 OO minutes. This is similar to the situation that currently exists in the Champaign-Urbana area. Overall, the simulation results indicated that a food waste collection program should leave commercial collection costs relatively unaffected. At worst, a food waste collection program may add 2 percent to a community’s commercial collection cost. The worst situation is case two in which the food collection frequency is increased by a factor of three and the disposal distance is the same for both garbage and food. The best case shows a collection cost reduction for commercial waste to be approximately 5 percent. This gain was found for case three in which food waste is collected at the same waste frequency as in the original garbage collection system and the disposal

0

2000

4000

6000

Corrugated

container

8000

10000

12000

weight (pounds)

G + F = Garbage plus food. CC = Corrugated containers. (1)

~~~;~a~lus

food tends to be 1.39 times Ithe generation

rate of cornrgated

Source: Ty Newell, Elizabeth Markstahler and Matthew Snyder, An Invesfigation of Commercill Generated Food Waste and Recyclable MateriaIs, Community Recylcing c! enter, December 1992.

distance for food is approximately onethird the distance of garbage disposal. While the specific costs are very dependent on equipment, labor, maintenance, insurance and other cost factors, the system assumed for the simulation showed collection costs to be approximately $45 per ton with approximately half for labor and the other half for trucks, roll-off containers, maintenance and fuel. The food waste collection program would result in a collection cost variation of $1 to $2 per ton of commercial waste generated. In terms of equipment, the simulation indicated that the community would have a commercial collection fleet of approximately 22 to 23 collection vehicles. The food waste program would shift one to three trucks to food waste collection, depending on the participation level obtained. In terms of cost justification, a commercial food waste collection program would be viable when the cost associated with food waste processing is competitive with garbage disposal costs. Because of the relatively low collection cost for commercial waste (compared to residential waste collection in which collection costs dominate), waste processing cost differences have a larger impact.

Conclusions The commercial food waste study has provided information that is valuable for understanding some of the characteristics of a commercial food waste collection program. Although the business sample is small, the range of businesses covered (in both size and characteristics) has been sufficient to develop the confidente that starting a commercial food waste collection program can have a significant impact on a community’s waste stream without causing significant problems to its current waste collection system. Methods for estimating the amount of food waste that can be recovered from restaurants and food stores have been developed; however, one must always be aware that each waste generator has its own characteristics. RR Information on the kNOw WASTE Collector software is available from the Community Recycling Center, 720 Market Street, Champaign, IL 61820; (217) 351-4495. Acknowledgments The authors express their appreciation to the Illinois Department of Energy and Natural Resources for supporting the work described in this paper.

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61 1993