3.2.2. Degradation of poplar solids
Reduction of TS, VS, cellulose and hemicellulose were calculated to evaluate the efficiency of anaerobic digestion. As shown in Tables 5A and 5B, reductions of TS and VS for NaOH-treated poplar processing residues were higher than the untreated controls at all concentrations. TS and VS reductions of NaOH-treated poplar pro- cessing residues ranged from 22.9% to 43.6%, and from 23.6% to 49.0%, respectively, which were increased by 2.9–5.3-fold, and by 2.4–3.9-fold accordingly, compared to those of the untreated ones. In general, TS and VS reductions were elevated, with NaOH dose in- creased from 3.0% to 7.0% at all concentrations. The result that reductions of the cellulose and hemicellulose for NaOH-treated poplar processing residues were higher than those of the untreated one at all concentrations, which was similar to that of the TS and VS. As shown in Tables 5C and 5D, cellulose and hemicellulose reductions of NaOH-treated poplar processing residues ranged from 54.4% to 73.1% and from 19.6% to 53.3%, respectively, which were increased by 1.3–3.1-fold, and by 2.7–24.7-fold accordingly,