Landfill

NatureWorks LLC is designing polymer materials to be more environmentally sustainable (i.e. closing the loop and being a part of nature’s carbon cycle). Landfills take valuable biowastes like food, paper and organics and are preventing it from entering the natural biological carbon cycle (50% of the Municipal Solid Waste stream is organic biowastes).

Landfills are the last resource for waste management.

Remember, the three R's --Reduce, Reuse, and Recycle.

NatureWorks^® biopolymer fits into weight reduction over traditional packaging (i.e. glass), physical recycling by collection and hydrolysis, biological recycling by composting, anaerobic digestion, and landfill gas energy recovery should it degrade in a managed landfill.

Landfills are decreasing in number; for example in the United States it fell from 8,000 in 1988 to 1,654 in 2004. The United States Environmental Protection Agency (USEPA) has promulgated New Source Performance Standards and Emission Guidelines for landfills pursuant to mandates in the Clean Air Act. These rules require landfills to collect landfill gas and prescribe design standards and performance limits for gas extraction systems to use for energy purposes.

In the latest version in 2001, the popular book Rubbish revealed that landfills are not buried pits of decay, as generally assumed, but rather tombs that preserve much of the buried waste. The book, which chronicles the findings of the University of Arizona’s archeological “Garbage Project,” tells of newspapers that are readable after being buried for 30 years in the landfill. It describes the discovery whole and recognizable food items excavated from landfills, like the 15-year old T-bone steak with the meat and fat still clinging to the bone. Other investigations have similarly demonstrated that landfills preserve a large portion of the resident organic matter. In general, the extent of decomposition found among different landfills, and within a given landfill, is inconsistent depending on the amount and distribution of moisture.

NatureWorks biopolymer is made primarily of polylactic acid (PLA), a repeating chain of lactic acid, which undergoes a 2-step degradation process. First, the moisture and heat attack the NatureWorks biopolymer chains and split them apart, creating smaller polymers, and finally, lactic acid. Microorganisms which would be present in compost and soil consume the smaller biopolymer fragments and lactic acid as nutrients. Since lactic acid is widely found in nature, a large number of organisms metabolize lactic acid, completing the cycle. The rate of the initial chemical hydrolysis is temperature and humidity dependent, and conditions in a landfill are expected to result in relatively slow degradation due to lack of moisture and soil temperatures.

The fate of NatureWorks biopolymer and other biowastes based on an inactive landfill model is unlikely to be biologically consumed to a large extent based on above studies due to lack and distribution of moisture. Thus NatureWorks biopolymer would not become biologically active and contribute to methane production.

If NatureWorks biopolymer was placed in a biologically actively landfill, it would actively biodegrade with other the biowastes (the organic wastes) and the methane gas would be captured for power generation, leaving behind a stable, inert material. This would return NatureWorks biopolymer into nature’s carbon cycle without the legacy costs to future generations.

NatureWorks biopolymer has the potential to be disposed of via a variety of conventional methods and offer new options for the future, including industrial composting.

The multiple disposal alternatives of NatureWorks biopolymer means it can play a key role in landfill diversion.  NatureWorks biopolymer has been successfully composted in applications where collection is feasible and a commercial composting infrastructure is in place. If land-filled, PLA is inert – it contains no harmful toxins that can leach into the soil.

Trials by leading machine sorting system manufacturers show that NatureWorks biopolymer can be separated from the post-consumer RPET (recycled Polyethylene Terapthalate) stream, and can be separated into its own stream when post-consumer amounts warrant. NatureWorks LLC continues to work with recycling stakeholders to ensure the successful integration of PLA into the recycling stream.  In addition to its ability to be mechanically recycled and composted, NatureWorks biopolymer has shown favorable properties for use where incineration is the preferred waste disposal system and offers potential for chemical recycling. 

To assist recyclers in North America, NatureWorks LLC has established a post-consumer bottles buy-back program to facilitate the removal of collected PLA bottles until the market for recycled PLA has matured.