This work provided a detailed observation on hydrothermal
carbonization of paper sludge. HTC pre-treatment significantly
improved fuel qualities of hydrochars.
Higher than 8% of higher heating value was increased due to
increase of fixed carbon and decrease of volatile matter, especially
for PS-210. The energetic recovery efficiency showed
210 C was the optimal reaction temperature.
Lower H/C and O/C atomic ratios of hydrochars were achieved
with raising the reaction temperature. In addition, enhanced
environmental benefits could be achieved by utilization of
hydrochars due to reduction of nitrogen and sulfur contents.
The HTC process showed high removal rates of chlorine, sodium
and potassium. As a consequence, the ash-related problems
were significantly mitigated.
The TGA results showed the combustion behavior of hydrochars
was greatly influenced by the reaction temperature, leading to a
better combustion performance. And average activation energies
of hydrochars were higher when compared to PS.