shows the elemental analysis of bottom ash from pure
woodchip gasification (PWG) and 20% sludge/woodchip co-gasifi-
cation (20SWCG) with the different ranges of particle size obtained
after sieving. It can be seen that both PWG and 20SWCG bottom
ashes with the particle size of higher than 500 lm have high carbon
content (>50 wt.%). This result suggests that these two bottom
ashes should be re-used as a feedstock for gasification in order to
recover more energy. Therefore, only the bottom ashes with the
particle size lower than 500 lm were considered as the bottom
ash wastes and used for the following studies.