Disposal of Solid Wastes from Paper Industry using a CHTC Based Technology—Optimization of the Treatment Conditions

In a previous study, we explored the feasibility of applying the catalytic hydro- thermal conversion (CHTC) technique in treating organic wastes from pulp and paper mills. In the present study, we focused on optimization of the conversion process based on sludge and process rejects of a wastepaper based whiteboard mill. Under a 70% MC, heating to reaction temperature of 750℃ with 10 g of o.d. sludge, an equal part heating medium (sericite) and ca. 5% sodium carbonate catalyst produced 59% of hydrogen in the flue gas for a total 3770 ml hydrogen yield. The same quantity of the coarse-particle process rejects, on the other hand produced under the best condition 40% hydrogen in the flue gas for a total of 3173 ml hydrogen yield. A factorial design using solid waste particle sizes, catalyst doses, heating medium amounts and reaction temperature as variables showed that for the sludge sample, the interactions of heating medium amounts, waste particle sizes, and catalyst doses had a major effect; with the overall multiple variable effects greater than those of the single variables. As for the process rejects, ANOVA indicated that the interactions of catalyst doses, heating medium amounts and temperature had the greatest effect, while the single variable effects of particle sizes and catalyst doses were also notable.