Characterization of Products from Fast Micropyrolysis of Municipal Solid Waste Biomass

Biomass feedstock costs remain one of the largest impediments to biofuel production economics. Municipal solid waste (MSW) represents an attractive feedstock with year-round availability, an established collection infrastructure paid for by waste generators, low cost, and the potential to be blended with higher cost feedstocks to reduce overall feedstock costs. Paper waste, yard waste, and construction and demolition waste (C&D) were examined for their applicability in the pyrolysis conversion pathway. Paper waste consisted of nonrecyclable paper such as mixed low grade paper, food and beverage packaging, kitchen paper wastes and coated paper; yard waste consisted of grass clippings, and C&D wastes consisted of engineered wood products obtained from a construction waste landfill. The waste materials were tested for thermochemical conversion potential using a bench scale fast micropyrolysis process. Bio-oil yields were the highest for the C&D materials and lowest for the paper waste. The C&D wastes had the highest level of lignin derived compounds (phenolic and cyclics), while the paper waste had higher levels of carbohydrate derived compounds (aldehydes, organic acids, ketones, alcohols, and sugars). However, the paper material had higher amounts of lignin derived compounds than expected based upon lignin content that is likely due to the presence of polyphenolic resins used in paper processing. The paper and yard wastes had significantly higher levels of ash content than the C&D wastes (14-15% versus 0.5-1.3%), which further correlated to higher levels of alkali and alkaline earth metals, which are known to reduce the amount of pyrolysis bio-oil produced. The effect of acid washing was evaluated for grass clipping and waste paper, and the amount of bio-oil produced was increased from 58% to 73% and 67% to 73%, respectively.