Gasification of sewage sludge using a throated downdraft gasifier and uncertainty analysis

The kinetics of gasification of char derived from sewage sludge

“…Gasification of sewage sludge as well as co-gasification with coal as integrated processes involving primary and secondary reactions have been widely investigated during recent years [11][12][13][14][15][16][17][18]. However, the literature on the reaction of sewage sludge char with an oxidizing agent, which is considered as the most important step in the overall processes process, is very scarce, in contrast to the literature concerning the coal and biomass chars gasification reactions.…”

Supercritical Water Gasification of Municipal Sludge: A Novel Approach to Waste Treatment and Energy Recovery

“…Dewatering is expensive, and as energy costs continue to rise, drying processes are becoming increasingly prohibitive (Weismantel, 2001). Dry pyrolysis and gasification face similar thermoeconomic efficiency limitations to incineration, in that high-moisture levels in sludge cause ignition and combustion problems (Demirbas et al, 2011;Dogru et al, 2002). Specifically, traditional gasification technologies encounter operational air:fuel ratio and gas:ventilation mobility problems when the feedstocks exceed 30% moisture content, and sewage-sludge moisture content generally needs to start at less than 15% to serve as a proper feedstock for gasifiers (Dogru et al, 2002).…”

“…Dry pyrolysis and gasification face similar thermoeconomic efficiency limitations to incineration, in that high-moisture levels in sludge cause ignition and combustion problems (Demirbas et al, 2011;Dogru et al, 2002). Specifically, traditional gasification technologies encounter operational air:fuel ratio and gas:ventilation mobility problems when the feedstocks exceed 30% moisture content, and sewage-sludge moisture content generally needs to start at less than 15% to serve as a proper feedstock for gasifiers (Dogru et al, 2002). Plus, fuels produced require significant additional cleaning due to the presence of heavy metals and incomplete destruction of harmful organic compounds (Dogru et al, 2002).…”

“…Specifically, traditional gasification technologies encounter operational air:fuel ratio and gas:ventilation mobility problems when the feedstocks exceed 30% moisture content, and sewage-sludge moisture content generally needs to start at less than 15% to serve as a proper feedstock for gasifiers (Dogru et al, 2002). Plus, fuels produced require significant additional cleaning due to the presence of heavy metals and incomplete destruction of harmful organic compounds (Dogru et al, 2002). Indeed, traditional thermal technologies do destroy hazardous organic compounds, but only up to a point.…”

“…Indeed, traditional thermal technologies do destroy hazardous organic compounds, but only up to a point. Incineration-derived slag, for example, still contains all of the heavy metals, up to 30% of the original hazardous organic compounds, and additional secondary combustion compounds (Dogru et al, 2002;Fytili & Zabaniotou, 2008). Most contemporary thermal options are prohibitively costly due to high capital investment and increasingly stringent, air-quality permitting and compliance standards (Chun et al, 2011;Fytili & Zabaniotou, 2008).…”