CITY OF ORILLIA

BIODEGRADABLE BAG STUDY

December 2003Solid Waste Management Division

TABLE OF CONTENTS

1.0 INTRODUCTION .........................................................................................1

2.0 BACKGROUND...........................................................................................12.1 CERTIFICATION OF COMPOSTABLE BAGS.......................................................12.2 POTENTIAL FOR COMPOST CONTAMINATION ..................................................32.3 MUNICIPALITIES IN ONTARIO TESTING BIODEGRADABLE BAGS.........................42.3 BAG BRANDS STUDIED.................................................................................5

3.0 GOALS AND OBJECTIVES........................................................................6

4.0 METHODOLOGY ........................................................................................64.1 BAG STRENGTH TRIAL .................................................................................74.2 WINDROW TRIAL .........................................................................................7

5.0 RESULTS AND DISCUSSION ....................................................................85.1 BAG STRENGTH TRIAL .................................................................................8

5.1.1 Yard Waste Bags ................................................................................85.1.2 Kitchen Waste Bags............................................................................9

5.2 WINDROW TRIAL .......................................................................................105.2.1 BIOSAK® Bags.................................................................................105.2.2 BioBag® Bags...................................................................................115.2.3 BioTrue Bags ....................................................................................12

6.0 SUMMARY AND CONCLUSIONS ............................................................12

7.0 RECOMMENDATIONS..............................................................................13

REFERENCES ...................................................................................................13

LIST OF TABLES

TABLE 1: American and European heavy metal limits for compostable plastics aswell as limits for compost in Ontario................................................................3

TABLE 2: Product information for certified bag brands.........................................5

LIST OF FIGURES

FIGURE 1: Logo indicating that plastic product is certified compostable underASTM D6400-99. ............................................................................................3

FIGURE 2: Results for yard waste biodegradable bag strength trial.....................9

FIGURE 3: Results for kitchen waste biodegradable bag strength trial ..............10

LIST OF PHOTOS

PHOTO 1: Biodegradable yard waste bags in the storage compartment..............7

PHOTO 2: Windrow preparation with bags ...........................................................8

PHOTO 3: In tact BIOSAK® yard waste bag in a windrow pile after seven weeks......................................................................................................................11

PHOTO 4: Fragment of BioBag® yard waste bag in a windrow pile after sixweeks............................................................................................................11

PHOTO 5: BioTrue yard waste bag in a windrow pile after one week.................12

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1.0 Introduction

Currently residents of the City of Orillia are asked to place their yard waste in aclear plastic bag, a rigid container, or bundled and tied. The bags are openedand emptied by collection staff into the collection vehicle. The price charged bythe contractor for this service is likely to increase appreciably with the newcontract starting in July of 2004. Use of biodegradable plastic bags wouldfacilitate yard waste collection in that the bags would not have to be opened oremptied by collection staff, and hence, would minimize the collection pricecharged for this service.

The purpose of this study was to determine how well three brands of certifiedcompostable (biodegradable) bags performed both as a collection medium and inthe City’s windrow composting operation. The brands tested include BIOSAK®(W Ralston Inc.), BioBag® (BioCompostable Technologies Inc./Polar Gruppen),and BioTrue (BioTrue Biodegradable Film Products Inc./Farnell Packaging).

2.0 Background

Over the past decade a fair amount of research has been undertaken in Europeand North America regarding biodegradable plastics. When these products firstcame on the market in the 1980’s, they were made by mixing polyethylene withstarch. Such products were labelled biodegradable when in fact after the starchbroke down, plastic (polyethylene) fragments still remained (EPIC, 2001). Thisled to confusion as to whether these materials were doing what themanufacturers claimed they were supposed to do. Currently there are newerbiodegradable plastic products on the market which do in fact completely breakdown. These products are made from such materials as polyester, starch, andderivatives from vegetable oil.

There is a notable difference in terminology regarding a compostable versus abiodegradable plastic. A biodegradable plastic will break down into carbondioxide, water, and biomass (humus material). A compostable plastic refers to aplastic that breaks down in a composting environment as fast as the surroundingmaterial and leaves no visible, distinguishable or toxic material. A compostableplastic is not necessarily a biodegradable plastic since inorganic materials maybe left behind. A new certification process, however, ensures that designatedcompostable bags are in fact biodegradable.

2.1 Certification of Compostable Bags

In 1999 after eight years of study, the American Society for Testing and Materials(ASTM) developed a new series of tests and criteria to designate plastics as

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compostable. This designation is found in ASTM D6400-99 “Specifications forCompostable Plastics.” In order for a plastic to meet these standards it must:

1.) Biodegrade – Be converted rapidly to carbon dioxide, water andbiomass at the same rate as kraft paper and other compostablematerials;

2.) Disintegrate – Not be visible or need to be screened out aftercomposting;

3.) Be safe for the environment – Produce no harmful by-products orhinder the ability of the compost to support plant growth

The ASTM tests measure biodegradability, disintegration, and ecotoxicity and aremeasured as follows. A known quantity of active compost and test material (i.e.,the sample plastic) are placed in sealed flasks (as is the case with blank andcontrol materials). Temperature, oxygen, and moisture are maintained in theseflasks at optimum levels to sustain microbial activity.

Biodegradation is determined by measuring the amount of carbon dioxideproduced by the degrading plastic over a 180 day period (Narayan and Mojo, NoDate; Stevens, 2002). The percentage of the material which is mineralized isbased on the measured levels of carbon dioxide produced. A conversion ratio of60 percent or more is considered a pass, and is based on mineralization of kraftpaper.

Disintegration is measured by sieving the residue material left behind after thebiodegradation test. The product passes this test if less than 10 percent of theresidue material remains on a 2 mm screen. Once again, kraft paper is thereference material. This test ensures that any non-degraded pieces left overwould be indistinguishable in the compost.

Ecotoxicity is determined by measuring plant growth and germination for differentconcentrations of the resulting compost mixed with soil. If plant growth andgermination are significantly lower (statistically) than those of the controlcompost, the material will not pass this test.

In addition to these three tests, the plastic material must undergo chemicaltesting to ensure the product meets pollutant limits. This will be addressed in thenext section. Plastics which meet these standards can be affixed with the“Compostable” Logo from the Biodegradable Products Institute (BPI) asdisplayed in Figure 1.

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FIGURE 1: Logo indicating that plastic product is certified compostable underASTM D6400-99.

2.2 Potential for Compost Contamination

Compost produced at the Waste Diversion Site regularly meets metal andorganic chemical concentration limits set out in Schedule B of the landfill’sProvisional Certificate of Approval No. A25061 and Table 1 of Ontario Regulation101/94 for regular use compost. By meeting these limits, the City’s compost canbe sold to the public. As such, it is essential that if biodegradable bags are to beincorporated into the City’s composting operation, they do not add any sources ofcontamination to the final product.

The compostable bag certification process ensures that the three brands of bagstested will not reduce the quality of the compost the City produces. As well asmeeting the ASTM standards, these bags also meet European standards forcompostable plastics (EN 13432). The heavy metal limits set out in theEuropean standards are more stringent than those set out in the ASTMstandards. ASTM heavy metal limits are based on 50 percent of the legal limitfor soils in the United States. European limits are based on 50 percent of thequantities normally found in compost. Table 1 lists heavy metal limits under theASTM D6400-99 standards, the European EN 13432 standards, and O. Reg.101/94 limits for regular use compost.

TABLE 1: American and European heavy metal limits for compostable plastics aswell as limits for compost in Ontario

Concentration Limits (mg/kg)MetalASTM D6400-99 EN 13432 O. Reg. 101/94

ArsenicCadmiumChromiumCobaltCopperLeadMercuryMolybdenumNickelSeleniumZinc

20.517--

7501508.5-

21050

1400

50.550-

50500.51

250.75150

103

502560

1500.15

2602

500

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As can be seen in Table 1, the European limits meet or exceed those set out bythe MOE, except for mercury which is only slightly higher. Neither certificationhas a limit for cobalt.

According to Steven Mojo, the Executive Director of the Biodegradable PlasticsInstitute, no product which has been certified compostable has had any heavymetals added. Furthermore, the Region of Peel and the City of Peterboroughwho have also tested the certified bag brands examined in this study have notfound the bags to have any adverse affects on compost quality. In bothmunicipalities, the resulting compost has met O. Reg. 101/94 for regular compostand can be sold to the public. Therefore, there is no concern that these bags willaffect the City’s compost quality.

2.3 Municipalities in Ontario Testing Biodegradable Bags

Currently, two municipalities in Ontario are testing certified compostable bags intheir organics collection programs including the Region of Peel and the City ofPeterborough.

Peel Region has tested four brands of bags in their organics collection programssince May of 2002. Testing has occurred with 500 households in Mississauga,700 households in Brampton, 500 households in Bolton and 11,000 householdsin Caledon. The first bag tested (Ecostar – which is not certified) resulted incompost with some heavy metals contamination and the company since hasgone out of business. The second bag (BioTrue) has performed very well. Itbreaks down well although there were some difficulties with the bag breakingopen at the curb. The third bag (ECOSAFE – which breaks down slower thanASTM specifications) also performed well and is currently being used in Caledon.Both the BioTrue and ECOSAFE bags have not adversely affected compostquality and tests have shown that the resulting compost meets MOE Class Aguidelines (i.e., it can be sold as regular compost). The fourth bag tested was apaper bag. The Region is currently in the process of testing the BioBag® and hasso far had very good results, as the bag breaks down nicely. The Region is alsocurrently in talks with W Ralston about their product (BIOSAK®), which hasrecently come on the market.

The City of Peterborough has been running a pilot study at 650 homes for overtwo years using the 10 litre BioBag. Participating residents have been givenkitchen and curbside containers for their organics collection. Staff have foundthat 75 percent of the residents involved in the program are using the bagsdespite the extra cost. Of these participating residents, 87 percent are verysatisfied with the product. They have not experienced any problems with thebags breaking up at the curb (although there are concerns if the bags sit for morethan two weeks). The resulting compost has met O. Reg. 101/94 limits and Citystaff are very satisfied with the product.

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Other municipalities that are testing or using non-certified compostable bagsinclude the Region of Durham and Centre and South Hastings.

Durham Region was using a non-certified bag (BIO-SOLO™ from IndacoManufacturing Ltd.), as the company had won the Region’s tender to supplyresidents with sample bags. This tender was awarded before certified bags hadcome on the market. The plastic in these bags apparently does not biodegraderather just breaks apart. As well, it takes these bags 9 to 12 months to breakdown in the compost pile. The Region is currently promoting the use of certifiedbags, however, such bags are expensive.

Quinte Waste Solutions (for Centre and South Hastings) are currently using thenon-certified BIO-SOLO™ bags in their pilot study. Some problems with the bagsbreaking open at the curb were noticed, but the bags are cheap. No compostquality results were available since another company (Canadian Waste) handlesthe composting operation. The trial has been ongoing for about two years nowand Canadian Waste has not indicated any problems with the compost qualitylikely because the finished compost is used for landfill cover.

2.3 Bag Brands Studied

Three brands of certified compostable bags available in Canada were examinedin this study including BIOSAK® (W Ralston Inc.), BioBag® (BioCompostableTechnologies Inc./Polar Gruppen), and BioTrue (BioTrue Biodegradable FilmProducts Inc./Farnell Packaging). The BioBag® and the BIOSAK® bags aremade from the same plastic resin (Mater-Bi) produced in Europe by Novamont.This resin is used daily in over 3,000 European municipalities to collect organicwaste. The BioTrue bag is made from Easter Bio® resin which is made byEastman Chemical Inc.

Both yard and kitchen waste bags were examined. Product information on thesethree bags is outlined in Table 2.

TABLE 2: Product information for certified bag brandsCertified Compostable Bag BrandsProduct

Information BIOSAK® BioBag® BioTrueYard &Kitchen BagSizes

18” x 20”30” x 33”

16.9” x 17.7” 28.3” x 38.6”

16” x 16”33” x 39”

ResinComponents

Corn starch, polyester,and derivatives fromvegetable oil

Corn starch, polyester,and derivatives fromvegetable oil

Copolyester (made fromdiacids and glycols)

BreakdownPeriod Advertized

10 to 45 days 10 to 45 days 20 to 85 days

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TABLE 2: Continued…Certified Compostable Bag BrandsProduct

Information BIOSAK® BioBag® BioTrueEasilyIdentifiable?

Yes Yes Yes

Bag Strength Maintains strength for 1 to2 weeks.

Guaranteed to perform asa bag for at least 2 weeksin all types of weather

Fresh grass clippingsweaken bag after 1 week

Shelf Life 2 years 2 years 2 years

OtherMunicipalitiesUsing Product

In discussions withMarkham and Regions ofPeel and Durham

City of PeterboroughPeel Region

Peel Region, numerousmunicipalities in NovaScotia and in the U.S.

3.0 Goals and ObjectivesA number of goals and objectives were set out for this study. They include:

1.) Minimize yard waste collection costs for the City of Orillia.

2.) Determine how long the yard and kitchen waste biodegradable bagsremain in tact while holding organic material.

3.) Determine the length of time it takes the yard and kitchen wastebiodegradable bags to break down in a windrow composting operation.

4.) Determine if there are any additional odours produced in the windrowcomposting operation from the unopened bags.

4.0 Methodology

Two separate trials were undertaken in this study including a bag strength trialand a windrow trial. The bag strength trial involved testing how long the threebrands of yard and kitchen waste bags performed before breaking apart. Thewindrow trial involved placing yard and kitchen waste bags into three separatewindrow piles and examining how well the bags broke down and whether anyodours were noticed. The methodology followed for each trial is outlined in thefollowing sections.

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4.1 Bag Strength Trial

Bag strength was tested over a two week period or until the bags broke apart.Five replicate yard waste bags and five replicate kitchen waste bags weresampled for each of the three brands of certified bags. At least two of the fivereplicate yard waste bags were filled with fresh grass clippings so as to mimic aworse-case scenario. Waste Diversion staff filled the other three replicate yardwaste bags with mixed yard waste dropped off at the Waste Diversion Siteincluding leaves, plant residue, small branches, and clipped flowers. Kitchenwaste bags were filled with fresh food waste dropped off at the site from HuroniaRegional Centre in Orillia and included mashed potatoes, pasta, cookedvegetables, banana peels, and french fries.

Yard and food waste bags were placed in separate compartments of a storageunit with closing doors so as to mimic storage in a garage (Photo 1). Bags werechecked daily for any signs of breakage by lifting them up by their tops andexamining the circumference of each bag. Any holes or rips in the bags werenoted. Bag breakage was assumed to occur when the contents of the bagspilled out or when any rip was equal to or greater than half the circumference ofthe bag.

PHOTO 1: Biodegradable yard waste bags in the storage compartment

4.2 Windrow Trial

Waste Diversion staff prepared three separate windrow piles to test the threebrands of bags. Active compost was placed at the base of these piles. Filledyard and kitchen waste bags of the same brand were mixed together in each pile.The bags were then covered with month-old compost (Photo 2). Twenty-threereplicate yard waste bags and twenty-three replicate kitchen waste bags wereused in each pile for each of the three brands of bags. Staff filled yard andkitchen waste bags with fresh mixed yard waste and fresh food waste,respectively, as described previously. All the bags were tied shut.

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PHOTO 2: Windrow preparation with bags

Windrow piles were turned after the first week to examine any initial break-down.The piles were then left alone so as to allow each pile’s temperature to increaseto an optimal level. Due to the low volume of material in these piles, there wereinitially some difficulties with low pile temperatures. Because of this, more activecompost was placed on each pile during the fifth week of the study to ensure thepiles would actively compost. Once the piles reached temperatures of 55oC forat least three consecutive days, the piles were turned. After 6 weeks, the pileshad reached this temperature and were turned.

Compost temperatures were measured laterally at a depth of 1 meter internal tothe face of each pile. Monitoring occurred at four locations around each pile.Once the piles had reached at least 55oC for three consecutive days, the pileswere turned. Turning occurred roughly once a week after the sixth week of thestudy.

Observations of bag breakdown were recorded for a period of twelve weeks.Weekly inspections were undertaken and Waste Diversion staff providedfeedback on their observations of bag breakdown. Any noticeable odourproblems were recorded.

5.0 Results and Discussion

5.1 Bag Strength Trial

5.1.1 Yard Waste Bags

A storage door was left open containing two replicates of each brand of yardwaste bag after the first week of the trial. As such, results observed for thesebags during the second week of the study were disqualified and any bagbreakage which did occur was assumed to be the result of damage from wildlife.It should be noted that this affected only one BioTrue yard waste bag since the

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other one had broken open during the first week. This did not affect the otherthree replicate yard waste bags, nor did it affect any of the kitchen waste bags.

Both the BIOSAK® and BioBag® yard waste bags performed well during the twoweek test. There was some minor tearing during the second week in eachbrand’s yard waste bags which contained grass, but they did not break open.The other bags containing mixed yard waste did not break open. The similarresults found for BIOSAK® and the BioBag® are not surprising given that thebags are made of the same resin.

The BioTrue yard waste bags did not perform well in this test. One bagcontaining fresh grass clippings broke open only after three days while the otherbag containing grass broke apart after six days. Two of the other BioTrue bagscontaining mixed yard waste broke open after one week. Peel Region has alsonoticed some difficulties with these bags breaking open at the curb. Figure 2summarizes the bag strength results found for the three brands of yard wastebags.

FIGURE 2: Results for yard waste biodegradable bag strength trialTime (Days)Bag

BrandBagNo. 1 2 3 4 5 6 7 8 9 10 11 12 13 141234

BIOSAK®

51234

BioBag®

51234

BioTrue

5Note: 1.) Arrows represent length of time bag remained in tact

2.) Shaded areas represent disqualified results

5.1.2 Kitchen Waste Bags

All the brands of kitchen waste bags tested performed well strength wise. Two ofthe five BioTrue bags broke open (one at the end of the first week and the otherat the end of the second week). Otherwise no breakage occurred. Each bag,

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however, leaked water, and after a week the bags developed a mossy layer atthe base of each bag. Furthermore, fruit flies were noticed around each bag afterthe first day of sitting in storage. The BioBag® had the most leakage which is notsurprising given that they are designed to be somewhat porous. It should also beemphasized that wet food waste was placed in these bags and this provided aworst case scenario in terms of the types of food that may be disposed of.Figure 3 summarizes the bag strength results found for the three brands ofkitchen waste bags.

FIGURE 3: Results for kitchen waste biodegradable bag strength trialTime (Days)Bag Brand Bag

No. 1 2 3 4 5 6 7 8 9 10 11 12 13 141234

BIOSAK®

51234

BioBag®

51234

BioTrue

5Note: 1.) Arrows represent length of time bag remained in tact.

5.2 Windrow Trial

5.2.1 BIOSAK® Bags

After one week, there was noticeable breakdown in both the yard and kitchenwaste BIOSAK® bags. There were some torn areas, however, the bagsmaintained a strong shear strength. After six weeks, some yard waste bagswere still noticeable but appeared to be undergoing degradation as theyappeared shredded, however, one yard waste bag containing grass was found tobe in tact. No kitchen waste bags were noticed after six weeks. After sevenweeks one yard waste bag still remained in tact and is displayed in Photo 3.

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PHOTO 3: In tact BIOSAK® yard waste bag in a windrow pile after seven weeks

Some anaerobic odours were noticed after seven weeks. By weeks eight andnine, only scraps of yard waste bags were noticed and the bags appeared to bemostly broken down. The BIOSAK® bags took the longest to break down in thewindrow trial, however, they did appear to fully break down after twelve weeks asno remnants of the bags were observed.

5.2.2 BioBag® Bags

There was noticeable breakage in the yard and kitchen waste BioBag® bagsafter the first week. The bags had some torn areas but there was still a fairamount of shear strength left in the bags. After six weeks, the bags hadundergone appreciable degradation and only scraps of the bags were noticed(Photo 4). At this point, no kitchen waste bags were noticed. The bag fragmentsfound were more brittle but had some shear strength left in them.

PHOTO 4: Fragment of BioBag® yard waste bag in a windrow pile after sixweeks

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After seven weeks, the bags appeared to be heavily degraded. Only small darklystained bits of material were observed. Some small bits of bags were noticedafter eight and nine weeks. After eleven weeks, no bag fragments were noticedand it appeared the bags had completely broken down. The BioBag® was thesecond fastest bag to break down after the BioTrue bag.

5.2.3 BioTrue Bags

By far, the fastest bag to break down in the windrow trial was the BioTrue bag.After the first week, there was appreciable breakage in the yard waste bags(Photo 5) and no kitchen waste bags were noticed.

PHOTO 5: BioTrue yard waste bag in a windrow pile after one week

The bags were brittle when stretched after the first week. After six weeks nobags or bag fragments were observed. During weeks eight and nine, some smallbits of bags were seen. After eleven weeks, the bags appeared to havecompletely broken down as no fragments were observed. Although the BioTruebag performed poorly in the bag strength tests, it performed exceptionally well inthe windrow trial. This is not surprising given the bags appear to break down thefastest.

6.0 Summary and Conclusions

The results of this study indicate that the BIOSAK® and BioBag® yard wastebags performed very well both as a collecting medium and in the City of Orillia’swindrow composting operations undertaken at the Waste Diversion Site. Both ofthese bags lasted a full two weeks without breaking open, and hence, wouldlikely perform well at the curbside. The BIOSAK® yard waste bags had somedifficulty breaking down initially in the windrow pile, however, they appeared tofully break down once the twelve week study was complete.

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The BioTrue yard waste bag performed poorly in the bag strength trial, however,performed quite well in the windrow trial. The yard waste bags only lasted aweek or less before breaking open. Therefore, city residents are likely to havesome difficulties with these bags breaking open at the curb if they sit for a weekor more before being set out for collection. A thicker film is needed if this brandof bag is to be used successfully in yard waste collection programs. There are,however, no concerns with these bags in the City’s windrow compostingoperation. After six weeks in a windrow pile the bags had almost completelybroken down which made them the fastest to compost.

Each brand of kitchen waste bag performed quite well both in the bag strengthand windrow trials. The BIOSAK® and BioBag® kitchen waste bags did notbreak open over the two-week period and only one BioTrue bag broke open afterthe first week. Each bag did, however, leak water, develop a mossy layer andattract fruit flies after only a short period of sitting in the storage units. Much ofthis likely resulted from the wet food waste that was used in the bags.

7.0 Recommendations

1.) Both the BIOSAK® and the BioBag® biodegradable yard waste bags werefound to perform well as a collecting medium for yard waste and in theCity’s windrow composting operation. If the City is to purchase sampleyard waste bags for residents, either of these brands would be mostappropriate and only price should determine which product is purchased.

2.) If the City decides to promote the use of biodegradable kitchen wastebags for collecting kitchen organics, each brand (BIOSAK®, BioBag®, andBioTrue) has been found to be appropriate for such use.

References

Environment And Plastics Industry Council (EPIC). 2001. Special News andViews Report: New wave of biodegradable plastics capture niche markets.EPIC, Mississauga, ON (May 2001).

Narayan, R. and S. Mojo. No Year Given. Summary of ASTM D6400-99 TestMethod and Specifications & Correlation of Test Methods to Reral WorldComposting Results. International Biodegradable Products Institute.

Stevens, E.S. 2002. How green are green plastics? Biocycle. 43(12): 42-45.