Pollutant characteristics of the pyrolysis of petrochemical wastewater sludge by an electric furnace

Organic sludge represents significant reservoirs of renewable energy. Howev er, the pollution control costs of incinerator flue gases are high. An alte rnative to treating the sludge is low temperature pyrolysis process, which produces liquid oil rather than gases. The objective of this study is to ex amine pyrolysis of a petrochemical industrial sludge in an electric furnace . The pyrolysis was carried out in an isothermal reactor heated by a horizo ntal electric furnace. The element compositions of the sludge residues were analyzed with ICP. Concentrations of Zn, Cu, and Sb in a pyrolysis residue were increased with increased temperatures. This indicates that Zn, Cu, an d Sb were concentrated during pyrolysis process. Volatile organic compounds (VOCs) and volatile sulfur compounds were analyzed with CC/MS to assess th e exhaust gas compositions. The VOCs were generated from 400 to 900 degrees C, but their concentration was significantly decomposed at 900 degreesC. Th e concentration of volatile sulfur compounds increased when the pyrolysis t emperature was increased from 400 to 700 degreesC. When the pyrolysis tempe rature reached 300 degreesC, concentrations decreased. The rate constants, reaction orders, activation energy, and frequency factor were found by fitt ed nonlinear and linear regression. The average reaction order was 2.5, whe n pyrolysis temperatures ranged from 400 to 900 degreesC. The slope of acti vation energy (E-a/R) was 3243 and the frequency factor was 0.99 sec(-1).