Potential method for reducing emissions of polycyclic aromatic hydrocarbons from the incineration of biological sludge for the terephthalic acid manufacturing industry.

Abstract

This study illustrates a potential method for reducing PAH emissions from the incineration of biological sludge by adding a suitable and available waste as a co-fuel. The whole study was conducted on a full-scale fluidized-bed incinerator operated by a terephthalic acid (TPA) manufacturing plant for disposing of biological sludge. Two incinerating conditions were studied, one directly incinerating biological sludge (the normal incinerating condition), and the other adding the waste TPA as a co-fuel during the biological sludge incineration process (the trial incinerating condition). Both incinerating conditions used heavy oil as auxiliary fuel. Although the former had a higher heavy oil consumption rate than the latter, both had comparable combustion efficiencies. Results show that the total PAH input mass rate for the former was only 2.35 times higher than the latter, but the total PAH emission factor for the former was 6.52 times higher than the latter. Total PAH output/input mass ratios for both incinerating conditions were lower than unity, but the value for the normal incinerating condition was approximately 2.91 times higher than the trial condition. In conclusion, the use of waste TPA as a co-fuel not only saved the consumption of heavy oil but also reduced PAH emissions during the combustion process.