Seasonal and Long-Term Storage of Baled Municipal Solid Waste
Sammanfattning: Baling of MSW has been extensively used in Sweden and other countries for the storage of energy (biomass for energy) for incineration and production of either and or electricity and heat. Baling is performed in two principally different ways, leading to cylindrical- or rectangular bales. This work has focused on various parameters during the storage of MSW. The first parameters investigated were gaseous emissions CO2, O2, CH4 and volatile organic compounds (VOCs) from cylindrical and rectangular bales wrapped with plastic and unwrapped. A comparison of the two bale types was carried out with regard to VOCs. It was found that cylindrical and rectangular bales differ significantly. The emission of aromatic organic compounds was predominant in rectangular bales, while esters were predominant in cylindrical bales. Temperature was another parameter investigated. Firstly a comparison of three different interpolation methods: IDW, Thessian and ordinary kriging, was carried to enable accurate interpolation of temperature data. It was found that ordinary kriging was the most appropriate. The interpolation allowed for the 3-dimensional visualization of spatial and temporal distribution of temperature in bale storage. The interpolated temperatures were used to calculate material losses due to microbial degradation. It was estimated that between 10-15% of the structure mineralizes into carbon dioxide in 320 days. The analysis of the temperature distribution from seven different structures showed that the temperature does not increase above 70C. It was concluded that the risk of self ignition is minimal. Even though, fires do occur in storage of bale waste and in order to investigate the risk associated with a bale storage fire, a controlled fire experiment was carried out. The smoke was analyzed for various pollutant including polyaromatic hydrocarbons (PAHs) and dioxins. The concentrations measured were 15 ng/g sum of PAHs, 4.15 ng/g of naphthalene and 0.06 ng (ITEF-88)/g, 0.07 ng (ITEF-99)/ng and 0.07 ng (Eadons)/g respectively. The examples from literature and our own experiments show that waste storage areas should be more protected and prepared for fires, since a fire in a bale storage area can have a very high environmental and financial impact. Taking all in consideration, baling is an excellent method for temporary waste storage, especially for incineration. However baling is not advised as method for permanent storage as in landfills.
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