Greenhouse gases composting

PLA may be fabricated into film for packaging and is also made into fibers useful for carpeting (24). PLA is indeed biodegradable, but only under controlled composting conditions. Biodegradation of poly (lactic acid) requires temperatures of about 140 °F for many days to insure decomposition, ultimately into CO and water. Unfortunately, such conditions are not typical of landfills (3) or of most backyard compost heaps. Hence, even plastic bags made from PLA will not quickly disappear from the natural environment. Anaerobic decomposition of PLA results in liberation of methane, an even more potent greenhouse gas than CO (25-28). 

Life cycle assessment reveals that no petroleum-derived polymer can rival the greenhouse gas sink effect of the improved PLA process. Although disposal of PLA products - whether by combustion, composting or other conventional means - results in a return of carbon dioxide to the atmosphere, this advantage survives. 

Other potential opportunities for this group of materials exist in the fast-food industry. For example, if all plates, cups, packaging, and so on were based on biodegradable materials, they could be commingled with food waste and then composted in large-scale operations. Not only would these measures reduce the amount of material entering landfills, but if the polymers were derived from renewable materials, a reduction in greenhouse gas emissions would result. 

According the current state of knowledge, landfills aeration leading to in-situ composting of deposited waste is a method that allows for the effective elimination of a long-term impact of landfills on the environment. It contributes to the attenuation of the role of landfill in a formation of greenhouse gas effect by preventing the production of methane which is the basic component of the gas release from a conventional landfill. However, the influence of waste aeration on N O production poses the important question within the scope of aerated landfill role in GHG emissions. This have to be clarified in the very near future. 

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