| Abstract [eng] |
The disposal of mixed waste in landfills, dump sites and open burning without material and energy recovery leads to resource loss, causes health problems, pollution and littering. Increasing energy demand for industrial and domestic application with rising costs due to scarcity motivates a constant search for alternative clean energy sources. Recovering energy from waste presents various incentives e.g. creating jobs, alleviating poverty, combating and mitigating climate change, protecting the environmental and reducing dependence on traditional fuels sources. Unfortunately, most non-biodegradable, high calorific value plastic waste fraction has little or no application in most developing world communities. Plastic waste with high calorific value (36-46MJ/kg) occupies the greatest portion of landfill space given their very slow degradability. When openly burned, plastics produce high pollutants such as VOCs, PAH and PCDD/F (dioxins). Plastic waste is now one of the major components of municipal solid waste (MSW). It is a mixture of various plastic products, mainly made from low density polyethylene (LDPE), high density polyethylene (HDPE), polypropylene (PP), polystyrene (PS), polyvinylchloride (PVC) and polyethylene-terephthalate (PET) plastics. HDPE, LDPE and PP are the most available plastic types among municipal plastic waste (MPW). Today in Lithuania, most types of plastic are polyolefin polymers, polypropylene, PP (19%), low density polyethylene, LDPE (17%) and high density polyethylene, HDPE (12%) respectively, with the largest use of the plastics being for packaging; around 40% In the last few decades, plastic consumption has increased. Annual consumption of municipal waste in Lithuania is about 1,3 million tons, which results in about 145 thousands tons of plastics waste. Approximately 40 wt% of this waste comes from packing and packaging. The EU Packing and Packaging Waste Directive (2004/12/CE) had the objective to reclaim or incinerate (using energy recovery) at least 60 wt% of packaging waste and to recycle between 55 wt% and 85 wt% of it. The general objective of this paper is to study the suitability of the pyrolysis process for the thermal treatment of plastic residue from a material recovery facility in Lithuania. The plastic residue from the material recovery facility is 20–30 wt% of the entire waste stream. Pyrolysis processing involves heating the material to moderate temperatures (400–700 °C) in the absence of oxygen. The organic components of the material are then decomposed, generating liquid (biooil) and gaseous products, which can be useful as fuels and or sources of chemicals and it would result in a much lower volume of waste to be placed in a landfill. Pyrolysis is especially appropriate for products or waste streams that contain waste plastics, organic waste and inorganic solid waste materials as exemplified by the waste stream analyzed in this study. |
