Co-pyrolysis Characteristics of Sewage Sludge and Vinegar Residue and Migration Law of Alkali Metals

The synergetic effects during co-pyrolysis of sewage sludge and vinegar residue were investigated concerning the product distribution and reaction kinetics by thermogravimetric analysis and vacuum fixed bed reactor, and the alkali metals migration rules was analyzed by atomic absorption spectrophotometer. Results indicated that there is a significantly synergetic effect during the co-pyrolysis process. Kinetics was analyzed by Kissinger-Akahira-Sunose (KAS) method, and the activation energies needed were 35.38%-29.49% decreased for the decomposition of mixture compared with theoretical calculation and the devolatilization index were 3.5 x 10(-8) lower than calculation. The synergetic effect resulted in an increase in gas yields but a decrease in char yield and liquid. The presence of vinegar residue promoted the devolatilization of sewage sludge, improved the syngas (H-2+CO) content in the gaseous products, and promoted the cracking reactions of large aromatic rings in the resulted char. In addition, the co -pyrolysis process has a good effect on increasing phenols and esters of its bio-oil. At the end of pyrolysis process, the exhalation rate of alkali elements reached 79.19%-86.73%.