INTERNATIONAL LATEX CONFERENCE 2015 Enhancing the Biodegradation of Waste Rubber A novel approach to sustainable management of discarded rubber materials Teresa Clark 8/12/2015 Rubber items are a critical part of modern society and a focus on the waste management of rubber is becoming more critical. Advancements have been made in recycling rubber waste, but a vast majority of rubber products are discarded into landfills. Sustainability efforts must include self-remediation through biodegradation of rubber (pre- consumer and post-consumer) in these waste sites. Current advancements provide insight into alternative methods of utilizing bio-mimicry to these return waste products to the natural carbon cycle, produce “green” energy and expand the scope of “Zero Waste”. Included are an assessment of the unique environment within landfills and the energy impact of utilizing these methods. Additionally, a brief update to the current progress in validating the biodegradation of rubber waste is included. Enhancing the Biodegradation of Waste Rubber International Latex Conference 2015 - Teresa Clark Contents Introduction .................................................................................................................................................. 2 Waste disposal of rubber materials .............................................................................................................. 2 Composting of Rubber .................................................................................................................................. 5 Recycling Non-Tire Rubber Waste ................................................................................................................ 5 Recycling Waste through Biodegradation .................................................................................................... 7 Carbon Recycling of Landfilled Rubber ......................................................................................................... 8 Biodegradation of Rubber ............................................................................................................................. 8 Bioremediation within Landfills .................................................................................................................... 9 Modern Landfill Design ............................................................................................................................... 10 Biodegradation Process in Modern Landfills .............................................................................................. 10 Microbial Biodegradation In Landfills ......................................................................................................... 11 The Value of LFG from Modern Landfills .................................................................................................... 12 Biodegradation Rates and GHG .................................................................................................................. 14 Energy Conversion of Landfilled Rubber ..................................................................................................... 15 Testing methods and results ....................................................................................................................... 16 Importance of Microbial Diversity in Testing .............................................................................................. 19 A Novel Approach to Rubber Waste ........................................................................................................... 20 Works Cited ................................................................................................................................................. 22 Figure 1 – Conversion of complex materials to .......................................................................................... 12 Figure 2 (Barlaz, Landfill Gas Modeling, 2010) ........................................................................................... 15 Figure 3 – ASTM D5511 performed for 195 days........................................................................................ 17 Figure 4- ASTM D5511 performed for 305 days. ........................................................................................ 17 Figure 5- ASTM D5526 performed for 200 days ......................................................................................... 17 Figure 6 – BMP performed for 110 days ..................................................................................................... 18 Figure 7 – BMP performed for 105 days ..................................................................................................... 18 Figure 8 – BMP performed for 175 days ..................................................................................................... 18 Figure 9 – BMP performed for 30 days ....................................................................................................... 19 © 2015 ENSO Plastics 1 Enhancing the Biodegradation of Waste Rubber International Latex Conference 2015 - Teresa Clark Introduction Rubber products are everywhere to be found, though most people don’t recognize rubber in all of its applications. Since 1920, the demand for rubber in manufacturing was primarily dependent on the automobile industry, the biggest consumer of rubber products. Today, rubber is used in a wide variety of other applications such as, radio and T.V sets and in telephones. Electric wires are made safe and more effective by rubber insulation. Rubber forms a part of many mechanical devices in the kitchen. It helps to exclude draughts and to insulate against noise. Sofas and chairs may be upholstered with foam rubber cushions, and beds may have natural rubber pillows and mattresses. Clothing and footwear may contain rubber: e.g. elasticized threads in undergarments or shoe soles and protective gloves. Most sports equipment, virtually all balls, and many mechanical toys contain rubber in some or all of their parts. Still other applications have been developed due to special properties of certain types of synthetic rubber, and there are now more than 100,000 types of articles using rubber as a raw material. (Eldho Abraham, 2011) While the production of rubber articles continues to increase, the waste of disposed rubber must be considered. Ideally, waste rubber should integrate seamlessly into the natural carbon cycle without any residual toxicity. A novel concept is to produce self-remediating rubber articles that take advantage of our existing waste disposal methods to create the most valuable end of life scenario. Waste disposal of rubber materials Rubber items are a critical part of modern society and as the use of rubber continues to increase, a focus on the waste management of rubber is paramount. The waste rubber formed in latex-based industries is around 10–15% of the rubber consumed (Eldho Abraham, 2011). While this is a significant amount of industrial waste, the post- consumer rubber waste is far greater. In the US alone the waste disposal of rubber and leather is 15,060,000,000lbs - an increase of over 250% in the last 40 years (See Table 1). Recovery for recycling of these materials is at 17.9%. In 1960 the recovery rate for rubber and leather was also at 17.9%, however it dropped drastically in 1980 to 3.1% and has been slowly recovering over the past 30 years (Table 2). Interestingly, as is seen in Table 3, virtually all the recovery is for durable tires, with no reportable amounts of rubber in other durables and non-durables being collected for recovery. So while advancements have been made in recycling rubber waste from tires, virtually all of non-tire rubber products are discarded into landfills. This is an increasingly concerning issue as the disposal of rubber articles can cause negative environmental impacts. An effective integrated waste management system includes waste collection and sorting, followed by one or more of the following options: recycling, biological treatment of organic materials, thermal treatment, and landfilling. Composition of solid waste varies among communities or regions; as such, there can be no single acceptable solution to solid waste management (SWM). The waste management options implemented, however, must both be environmentally sustainable and economically viable for all sectors of the community. (Caraban, 2008) In the US, the primary method of disposal is landfilling, with the remaining portions sent for recycling, composting and incineration. This is reflected in the number of facilities. In the US there are approximately 1908 operating landfills, 633 material reclamation facilities recycling) and 86 incineration sites. (EPA, Municipal Solid Waste Generation, Recycling, and Disposal in the United States, Tables and Figures for 2012) Other countries have higher landfill diversion, however this is typically limited to plastics, metals and paper and does not significantly impact the landfilling of rubber based disposable items, resulting in the disposal of most rubber waste in landfills as well. While landfilling is the primary disposal method for most all rubber products, with exception of approximately 40% in rubber tires, there can be serious detrimental aspects to disposing of rubber in this manner. Rubber materials are not inherently biodegradable within landfills, which leaves the material stagnant for hundreds of years. © 2015 ENSO Plastics 2 Enhancing the Biodegradation of Waste Rubber International