Influence of moisture content on the direct gasification of dewatered sludge via supercritical water

Abstract In the present study, the feasibility of the direct gasification of dewatered sludge in supercritical water and the effect of water content on supercritical water gasification of the dewatered sludge were investigated using a high-pressure autoclave at a constant temperature of 400 °C with residence time of 60 min and by adjusting water content by adding distilled water or using air-dried dewatered sludge. The results showed that dewatered sludge can be directly gasified in supercritical water, with water content ranging from 75 to 95 wt%. The total gas production was increased by decreasing the water content, and the gas yield was decreased. The CO2 yield was significantly affected by water content, whereas H2, CH4, and CO yields were slightly reduced. The liquid residue contained large amounts of organic matter (OM) and total phenols, thereby requiring further treatment before being discharged. The concentrations of OM and total phenols increased with a decrease in water content. Moreover, a serious carbonization reaction happened while carbon particles higher than 10 wt% (char/coke) were being formed in the solid residue.

[1]  Linghong Zhang,et al.  Energy recovery from secondary pulp/paper-mill sludge and sewage sludge with supercritical water treatment. , 2010, Bioresource technology.

[2]  A. Kruse,et al.  Char and Coke Formation as Unwanted Side Reaction of the Hydrothermal Biomass Gasification , 2008 .

[3]  Xiaohong Hao,et al.  Hydrogen production by biomass gasification in supercritical water: A parametric study , 2006 .

[4]  C. Xu,et al.  Liquefactions of peat in supercritical water with a novel iron catalyst , 2011 .

[5]  Morgan Fröling,et al.  Thermochemical biofuel production in hydrothermal media: A review of sub- and supercritical water technologies , 2008 .

[6]  Honghe Ma,et al.  Partial oxidation of municipal sludge with activited carbon catalyst in supercritical water. , 2010, Journal of hazardous materials.

[7]  Michael Jerry Antal,et al.  Carbon-Catalyzed Gasification of Organic Feedstocks in Supercritical Water† , 1996 .

[8]  Linghong Zhang,et al.  Supercritical water gasification of an aqueous by-product from biomass hydrothermal liquefaction with novel Ru modified Ni catalysts. , 2011, Bioresource technology.

[9]  C. Xu,et al.  Conversion of secondary pulp/paper sludge powder to liquid oil products for energy recovery by direct liquefaction in hot-compressed water. , 2008, Water research.

[10]  Kyoung S. Ro,et al.  Catalytic Wet Gasification of Municipal and Animal Wastes , 2007 .

[11]  Takuya Yoshida,et al.  Gasification of biomass model compounds and real biomass in supercritical water , 2004 .

[12]  Akrama Mahmoud,et al.  Electrical field: a historical review of its application and contributions in wastewater sludge dewatering. , 2010, Water research.

[13]  Liang Wang,et al.  Catalytic Hydrogen Production from Municipal Sludge in Supercritical Water with Partial Oxidation , 2007 .

[14]  A. Kruse,et al.  Biomass Gasification in Supercritical Water: Influence of the Dry Matter Content and the Formation of Phenols , 2003 .

[15]  Paul T. Williams,et al.  Hydrothermal Catalytic Gasification of Municipal Solid Waste , 2007 .

[16]  Liejin Guo,et al.  Thermodynamic modeling and analysis of biomass gasification for hydrogen production in supercritical water , 2007 .

[17]  Tapio Westerlund,et al.  Waste to energy by industrially integrated supercritical water gasification – Effects of alkali salts in residual by-products from the pulp and paper industry , 2011 .

[18]  Liejin Guo,et al.  Hydrogen production by coal gasification in supercritical water with a fluidized bed reactor , 2010 .

[19]  G. Nakhla,et al.  Sequential supercritical water gasification and partial oxidation of hog manure , 2010 .