Seasonal and Long-Term Storage of Baled Municipal Solid Waste

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

Emissions from baled municipal solid waste: II. Effects of different treatments and baling techniques on the emission of volatile organic compounds

This paper focuses on the volatile organic compound emissions from baled municipal solid waste (MSW). The analytical methodology was based on sampling with adsorbent tubes once a month during seven occasions within a time period of 1 year. Automated analyses were carried Out on-line work-up with thermal desorption directly connected to a gas chromatograph-mass spectrometer. The effect of different baling techniques, cylindrical and rectangular baling was compared. It was found that cylindrically baled MSW emitted larger concentration of esters than their rectangular counter parts. Conversely, aromatic compounds emissions dominated in rectangularly baled MSW This indicates that different degradation mechanisms operate in the waste bales. Cylindrical and rectangular bales are generally wrapped with six layers of 250 pm thick low density polyethylene (LDPE). It was observed that by wrapping an extra six layers of LDPE film onto the bales, the emissions from cylindrical bales increased while emissions from the rectangular counterpart decreased. Over time, the volatile organic Compound emissions from cylindrical bales decreased two orders of magnitudes from 96.2 +/- 20.8 mu g m(-3) in September 2003 to 0.80 +/- 0.07 pg m(-3) in July 2004. The rectangular bales exhibited an almost identical relative emission reduction from 54.4 +/- 4.3 pg m(-3) in September 2003 to 0.46 +/- 0.02 pg in 3 in July 2004. Future work will concentrate on full-scale storages, taking into account waste type, storage size, temperature development and the different baling techniques among other variables

Emissions from baled municipal solid waste: I. Methodological approach for investigation of gaseous emissions

This paper presents a methodological approach for the study of volatile organic compounds (VOCs) in air, emitted during storage of municipal solid waste in bales. Determination of VOCs was based on sampling with adsorbent tubes followed by automated analysis using on-line work-up with a thermal desorption unit directly connected to a gas chromatograph-mass spectrometer. Using calculation algorithms and multidimensional statistical analysis of large amounts of data collected, the information was compressed and Visualized. The approach was applied to initial measurements of emissions of VOCs from 24 bales composed of municipal solid waste, each bale stored in a wooden box. These bales were produced using the two types of baling equipment available, resulting in cylindrical or rectangular bales, with different densities. Hundreds of different VOCs emitted from these bales sorted out into groups with different chemical structure. Differences in VOC concentrations in air were found between wastes stored in cylindrical or rectangular bales. For instance, it was found that the concentration of VOCs (relative to the concentration of toluene), in the first experiment after storing, for cylindrical bales with six layers of LDPE was 115 +/- 10 mu g m(-3), while for rectangular bales it was only 64 +/- 8 mu g m(-3). The procedure used for data interpretation suggested different degradation mechanisms in different types of bales. The use of multiple data interfaces, multidimensional statistics and automated chemical analysis methods are likely to be more and more common for waste companies and waste research in the near future. This is due to the interdisciplinary nature of the subject that relies heavily on various areas of science and information technology