CITY OF ORILLIA BIODEGRADABLE BAG STUDY. December 2003 Solid Waste Management Division

Transcription

1 CITY OF ORILLIA BIODEGRADABLE BAG STUDY December 003 Solid Waste Management Division

2 TABLE OF CONTENTS 1.0 INTRODUCTION BACKGROUND CERTIFICATION OF COMPOSTABLE BAGS...1. POTENTIAL FOR COMPOST CONTAMINATION MUNICIPALITIES IN ONTARIO TESTING BIODEGRADABLE BAGS BAG BRANDS STUDIED GOALS AND OBJECTIVES METHODOLOGY BAG STRENGTH TRIAL WINDROW TRIAL RESULTS AND DISCUSSION BAG STRENGTH TRIAL Yard Waste Bags Kitchen Waste Bags WINDROW TRIAL BIOSAK Bags BioBag Bags BioTrue Bags SUMMARY AND CONCLUSIONS RECOMMENDATIONS...13 REFERENCES...13

3 LIST OF TABLES TABLE 1: American and European heavy metal limits for compostable plastics as well as limits for compost in Ontario...3 TABLE : Product information for certified bag brands...5 LIST OF FIGURES FIGURE 1: Logo indicating that plastic product is certified compostable under ASTM D FIGURE : 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 : 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 six weeks...11 PHOTO 5: BioTrue yard waste bag in a windrow pile after one week...1

4 1.0 Introduction Currently residents of the City of Orillia are asked to place their yard waste in a clear plastic bag, a rigid container, or bundled and tied. The bags are opened and emptied by collection staff into the collection vehicle. The price charged by the contractor for this service is likely to increase appreciably with the new contract starting in July of 004. Use of biodegradable plastic bags would facilitate yard waste collection in that the bags would not have to be opened or emptied by collection staff, and hence, would minimize the collection price charged for this service. The purpose of this study was to determine how well three brands of certified compostable (biodegradable) bags performed both as a collection medium and in the 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)..0 Background Over the past decade a fair amount of research has been undertaken in Europe and North America regarding biodegradable plastics. When these products first came on the market in the 1980 s, they were made by mixing polyethylene with starch. Such products were labelled biodegradable when in fact after the starch broke down, plastic (polyethylene) fragments still remained (EPIC, 001). This led to confusion as to whether these materials were doing what the manufacturers claimed they were supposed to do. Currently there are newer biodegradable plastic products on the market which do in fact completely break down. These products are made from such materials as polyester, starch, and derivatives from vegetable oil. There is a notable difference in terminology regarding a compostable versus a biodegradable plastic. A biodegradable plastic will break down into carbon dioxide, water, and biomass (humus material). A compostable plastic refers to a plastic that breaks down in a composting environment as fast as the surrounding material and leaves no visible, distinguishable or toxic material. A compostable plastic is not necessarily a biodegradable plastic since inorganic materials may be left behind. A new certification process, however, ensures that designated compostable bags are in fact biodegradable..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 1

5 compostable. This designation is found in ASTM D Specifications for Compostable Plastics. In order for a plastic to meet these standards it must: 1.) Biodegrade Be converted rapidly to carbon dioxide, water and biomass at the same rate as kraft paper and other compostable materials;.) Disintegrate Not be visible or need to be screened out after composting; 3.) Be safe for the environment Produce no harmful by-products or hinder the ability of the compost to support plant growth The ASTM tests measure biodegradability, disintegration, and ecotoxicity and are measured 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 and control materials). Temperature, oxygen, and moisture are maintained in these flasks at optimum levels to sustain microbial activity. Biodegradation is determined by measuring the amount of carbon dioxide produced by the degrading plastic over a 180 day period (Narayan and Mojo, No Date; Stevens, 00). The percentage of the material which is mineralized is based on the measured levels of carbon dioxide produced. A conversion ratio of 60 percent or more is considered a pass, and is based on mineralization of kraft paper. Disintegration is measured by sieving the residue material left behind after the biodegradation test. The product passes this test if less than 10 percent of the residue material remains on a mm screen. Once again, kraft paper is the reference material. This test ensures that any non-degraded pieces left over would be indistinguishable in the compost. Ecotoxicity is determined by measuring plant growth and germination for different concentrations of the resulting compost mixed with soil. If plant growth and germination are significantly lower (statistically) than those of the control compost, the material will not pass this test. In addition to these three tests, the plastic material must undergo chemical testing to ensure the product meets pollutant limits. This will be addressed in the next section. Plastics which meet these standards can be affixed with the Compostable Logo from the Biodegradable Products Institute (BPI) as displayed in Figure 1.

6 FIGURE 1: Logo indicating that plastic product is certified compostable under ASTM D Potential for Compost Contamination Compost produced at the Waste Diversion Site regularly meets metal and organic chemical concentration limits set out in Schedule B of the landfill s Provisional Certificate of Approval No. A5061 and Table 1 of Ontario Regulation 101/94 for regular use compost. By meeting these limits, the City s compost can be sold to the public. As such, it is essential that if biodegradable bags are to be incorporated into the City s composting operation, they do not add any sources of contamination to the final product. The compostable bag certification process ensures that the three brands of bags tested will not reduce the quality of the compost the City produces. As well as meeting the ASTM standards, these bags also meet European standards for compostable plastics (EN 1343). The heavy metal limits set out in the European standards are more stringent than those set out in the ASTM standards. ASTM heavy metal limits are based on 50 percent of the legal limit for soils in the United States. European limits are based on 50 percent of the quantities normally found in compost. Table 1 lists heavy metal limits under the ASTM D standards, the European EN 1343 standards, and O. Reg. 101/94 limits for regular use compost. TABLE 1: American and European heavy metal limits for compostable plastics as well as limits for compost in Ontario Metal Arsenic Cadmium Chromium Cobalt Copper Lead Mercury Molybdenum Nickel Selenium Zinc Concentration Limits (mg/kg) ASTM D EN 1343 O. Reg. 101/

7 As can be seen in Table 1, the European limits meet or exceed those set out by the MOE, except for mercury which is only slightly higher. Neither certification has a limit for cobalt. According to Steven Mojo, the Executive Director of the Biodegradable Plastics Institute, no product which has been certified compostable has had any heavy metals added. Furthermore, the Region of Peel and the City of Peterborough who have also tested the certified bag brands examined in this study have not found the bags to have any adverse affects on compost quality. In both municipalities, the resulting compost has met O. Reg. 101/94 for regular compost and can be sold to the public. Therefore, there is no concern that these bags will affect the City s compost quality..3 Municipalities in Ontario Testing Biodegradable Bags Currently, two municipalities in Ontario are testing certified compostable bags in their organics collection programs including the Region of Peel and the City of Peterborough. Peel Region has tested four brands of bags in their organics collection programs since May of 00. Testing has occurred with 500 households in Mississauga, 700 households in Brampton, 500 households in Bolton and 11,000 households in Caledon. The first bag tested (Ecostar which is not certified) resulted in compost with some heavy metals contamination and the company since has gone out of business. The second bag (BioTrue) has performed very well. It breaks down well although there were some difficulties with the bag breaking open at the curb. The third bag (ECOSAFE which breaks down slower than ASTM specifications) also performed well and is currently being used in Caledon. Both the BioTrue and ECOSAFE bags have not adversely affected compost quality and tests have shown that the resulting compost meets MOE Class A guidelines (i.e., it can be sold as regular compost). The fourth bag tested was a paper bag. The Region is currently in the process of testing the BioBag and has so far had very good results, as the bag breaks down nicely. The Region is also currently in talks with W Ralston about their product (BIOSAK ), which has recently come on the market. The City of Peterborough has been running a pilot study at 650 homes for over two years using the 10 litre BioBag. Participating residents have been given kitchen and curbside containers for their organics collection. Staff have found that 75 percent of the residents involved in the program are using the bags despite the extra cost. Of these participating residents, 87 percent are very satisfied with the product. They have not experienced any problems with the bags breaking up at the curb (although there are concerns if the bags sit for more than two weeks). The resulting compost has met O. Reg. 101/94 limits and City staff are very satisfied with the product. 4

8 Other municipalities that are testing or using non-certified compostable bags include the Region of Durham and Centre and South Hastings. Durham Region was using a non-certified bag (BIO-SOLO from Indaco Manufacturing Ltd.), as the company had won the Region s tender to supply residents with sample bags. This tender was awarded before certified bags had come on the market. The plastic in these bags apparently does not biodegrade rather just breaks apart. As well, it takes these bags 9 to 1 months to break down in the compost pile. The Region is currently promoting the use of certified bags, however, such bags are expensive. Quinte Waste Solutions (for Centre and South Hastings) are currently using the non-certified BIO-SOLO bags in their pilot study. Some problems with the bags breaking open at the curb were noticed, but the bags are cheap. No compost quality results were available since another company (Canadian Waste) handles the composting operation. The trial has been ongoing for about two years now and Canadian Waste has not indicated any problems with the compost quality likely because the finished compost is used for landfill cover..3 Bag Brands Studied Three brands of certified compostable bags available in Canada were examined in this study including BIOSAK (W Ralston Inc.), BioBag (BioCompostable Technologies Inc./Polar Gruppen), and BioTrue (BioTrue Biodegradable Film Products Inc./Farnell Packaging). The BioBag and the BIOSAK bags are made 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 organic waste. The BioTrue bag is made from Easter Bio resin which is made by Eastman Chemical Inc. Both yard and kitchen waste bags were examined. Product information on these three bags is outlined in Table. TABLE : Product information for certified bag brands Product Certified Compostable Bag Brands Information BIOSAK BioBag BioTrue Yard & Kitchen Bag Sizes 18 x 0 30 x x x x x 39 Resin Components Breakdown Period Advertized Corn starch, polyester, and derivatives from vegetable oil Corn starch, polyester, and derivatives from vegetable oil Copolyester (made from diacids and glycols) 10 to 45 days 10 to 45 days 0 to 85 days 5

9 TABLE : Continued Product Certified Compostable Bag Brands Information BIOSAK BioBag BioTrue Easily Identifiable? Yes Yes Yes Bag Strength Maintains strength for 1 to weeks. Guaranteed to perform as a bag for at least weeks in all types of weather Shelf Life years years years Fresh grass clippings weaken bag after 1 week Other Municipalities Using Product In discussions with Markham and Regions of Peel and Durham City of Peterborough Peel Region Peel Region, numerous municipalities in Nova Scotia and in the U.S. 3.0 Goals and Objectives A number of goals and objectives were set out for this study. They include: 1.) Minimize yard waste collection costs for the City of Orillia..) Determine how long the yard and kitchen waste biodegradable bags remain in tact while holding organic material. 3.) Determine the length of time it takes the yard and kitchen waste biodegradable bags to break down in a windrow composting operation. 4.) Determine if there are any additional odours produced in the windrow composting operation from the unopened bags. 4.0 Methodology Two separate trials were undertaken in this study including a bag strength trial and a windrow trial. The bag strength trial involved testing how long the three brands of yard and kitchen waste bags performed before breaking apart. The windrow trial involved placing yard and kitchen waste bags into three separate windrow piles and examining how well the bags broke down and whether any odours were noticed. The methodology followed for each trial is outlined in the following sections. 6

10 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 were sampled for each of the three brands of certified bags. At least two of the five replicate yard waste bags were filled with fresh grass clippings so as to mimic a worse-case scenario. Waste Diversion staff filled the other three replicate yard waste bags with mixed yard waste dropped off at the Waste Diversion Site including leaves, plant residue, small branches, and clipped flowers. Kitchen waste bags were filled with fresh food waste dropped off at the site from Huronia Regional Centre in Orillia and included mashed potatoes, pasta, cooked vegetables, banana peels, and french fries. Yard and food waste bags were placed in separate compartments of a storage unit with closing doors so as to mimic storage in a garage (Photo 1). Bags were checked daily for any signs of breakage by lifting them up by their tops and examining the circumference of each bag. Any holes or rips in the bags were noted. Bag breakage was assumed to occur when the contents of the bag spilled out or when any rip was equal to or greater than half the circumference of the bag. PHOTO 1: Biodegradable yard waste bags in the storage compartment 4. Windrow Trial Waste Diversion staff prepared three separate windrow piles to test the three brands of bags. Active compost was placed at the base of these piles. Filled yard and kitchen waste bags of the same brand were mixed together in each pile. The bags were then covered with month-old compost (Photo ). Twenty-three replicate yard waste bags and twenty-three replicate kitchen waste bags were used in each pile for each of the three brands of bags. Staff filled yard and kitchen waste bags with fresh mixed yard waste and fresh food waste, respectively, as described previously. All the bags were tied shut. 7

11 PHOTO : 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 increase to an optimal level. Due to the low volume of material in these piles, there were initially some difficulties with low pile temperatures. Because of this, more active compost was placed on each pile during the fifth week of the study to ensure the piles would actively compost. Once the piles reached temperatures of 55 o C for at least three consecutive days, the piles were turned. After 6 weeks, the piles had reached this temperature and were turned. Compost temperatures were measured laterally at a depth of 1 meter internal to the face of each pile. Monitoring occurred at four locations around each pile. Once the piles had reached at least 55 o C for three consecutive days, the piles were turned. Turning occurred roughly once a week after the sixth week of the study. Observations of bag breakdown were recorded for a period of twelve weeks. Weekly inspections were undertaken and Waste Diversion staff provided feedback on their observations of bag breakdown. Any noticeable odour problems were recorded. 5.0 Results and Discussion 5.1 Bag Strength Trial Yard Waste Bags A storage door was left open containing two replicates of each brand of yard waste bag after the first week of the trial. As such, results observed for these bags during the second week of the study were disqualified and any bag breakage 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 8

12 other one had broken open during the first week. This did not affect the other three 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 two week test. There was some minor tearing during the second week in each brand 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 similar results found for BIOSAK and the BioBag are not surprising given that the bags are made of the same resin. The BioTrue yard waste bags did not perform well in this test. One bag containing fresh grass clippings broke open only after three days while the other bag containing grass broke apart after six days. Two of the other BioTrue bags containing mixed yard waste broke open after one week. Peel Region has also noticed some difficulties with these bags breaking open at the curb. Figure summarizes the bag strength results found for the three brands of yard waste bags. FIGURE : Results for yard waste biodegradable bag strength trial Bag Bag Time (Days) Brand No BIOSAK BioBag BioTrue Note: 1.) Arrows represent length of time bag remained in tact.) Shaded areas represent disqualified results 5.1. Kitchen Waste Bags All the brands of kitchen waste bags tested performed well strength wise. Two of the five BioTrue bags broke open (one at the end of the first week and the other at the end of the second week). Otherwise no breakage occurred. Each bag, 9

13 however, leaked water, and after a week the bags developed a mossy layer at the base of each bag. Furthermore, fruit flies were noticed around each bag after the first day of sitting in storage. The BioBag had the most leakage which is not surprising given that they are designed to be somewhat porous. It should also be emphasized that wet food waste was placed in these bags and this provided a worst 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 of kitchen waste bags. FIGURE 3: Results for kitchen waste biodegradable bag strength trial Bag Brand Bag Time (Days) No BIOSAK BioBag BioTrue Note: 1.) Arrows represent length of time bag remained in tact. 5. Windrow Trial 5..1 BIOSAK Bags After one week, there was noticeable breakdown in both the yard and kitchen waste BIOSAK bags. There were some torn areas, however, the bags maintained a strong shear strength. After six weeks, some yard waste bags were still noticeable but appeared to be undergoing degradation as they appeared shredded, however, one yard waste bag containing grass was found to be in tact. No kitchen waste bags were noticed after six weeks. After seven weeks one yard waste bag still remained in tact and is displayed in Photo 3. 10

14 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 and nine, only scraps of yard waste bags were noticed and the bags appeared to be mostly broken down. The BIOSAK bags took the longest to break down in the windrow trial, however, they did appear to fully break down after twelve weeks as no remnants of the bags were observed. 5.. BioBag Bags There was noticeable breakage in the yard and kitchen waste BioBag bags after the first week. The bags had some torn areas but there was still a fair amount of shear strength left in the bags. After six weeks, the bags had undergone appreciable degradation and only scraps of the bags were noticed (Photo 4). At this point, no kitchen waste bags were noticed. The bag fragments found were more brittle but had some shear strength left in them. PHOTO 4: Fragment of BioBag yard waste bag in a windrow pile after six weeks 11

15 After seven weeks, the bags appeared to be heavily degraded. Only small darkly stained bits of material were observed. Some small bits of bags were noticed after eight and nine weeks. After eleven weeks, no bag fragments were noticed and it appeared the bags had completely broken down. The BioBag was the second fastest bag to break down after the BioTrue bag 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 no bags or bag fragments were observed. During weeks eight and nine, some small bits of bags were seen. After eleven weeks, the bags appeared to have completely broken down as no fragments were observed. Although the BioTrue bag performed poorly in the bag strength tests, it performed exceptionally well in the windrow trial. This is not surprising given the bags appear to break down the fastest. 6.0 Summary and Conclusions The results of this study indicate that the BIOSAK and BioBag yard waste bags performed very well both as a collecting medium and in the City of Orillia s windrow composting operations undertaken at the Waste Diversion Site. Both of these bags lasted a full two weeks without breaking open, and hence, would likely perform well at the curbside. The BIOSAK yard waste bags had some difficulty breaking down initially in the windrow pile, however, they appeared to fully break down once the twelve week study was complete. 1

16 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 a week or less before breaking open. Therefore, city residents are likely to have some difficulties with these bags breaking open at the curb if they sit for a week or more before being set out for collection. A thicker film is needed if this brand of bag is to be used successfully in yard waste collection programs. There are, however, no concerns with these bags in the City s windrow composting operation. After six weeks in a windrow pile the bags had almost completely broken down which made them the fastest to compost. Each brand of kitchen waste bag performed quite well both in the bag strength and windrow trials. The BIOSAK and BioBag kitchen waste bags did not break open over the two-week period and only one BioTrue bag broke open after the first week. Each bag did, however, leak water, develop a mossy layer and attract fruit flies after only a short period of sitting in the storage units. Much of this 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 were found to perform well as a collecting medium for yard waste and in the City s windrow composting operation. If the City is to purchase sample yard waste bags for residents, either of these brands would be most appropriate and only price should determine which product is purchased..) If the City decides to promote the use of biodegradable kitchen waste bags for collecting kitchen organics, each brand (BIOSAK, BioBag, and BioTrue) has been found to be appropriate for such use. References Environment And Plastics Industry Council (EPIC) Special News and Views Report: New wave of biodegradable plastics capture niche markets. EPIC, Mississauga, ON (May 001). Narayan, R. and S. Mojo. No Year Given. Summary of ASTM D Test Method and Specifications & Correlation of Test Methods to Reral World Composting Results. International Biodegradable Products Institute. Stevens, E.S. 00. How green are green plastics? Biocycle. 43(1):