Relationship between physicochemical properties and dewaterability of hydrothermal sludge derived from different source.

Sewage sludge (SS) and deinking sludge (DS) were used to comparatively study the hydrothermal dewatering of sludge with different components. For a better overview, an insight into the relationship between physicochemical properties and dewaterability of hydrothermal sludge was provided. Results found that not all kinds of sludge were suitably conditioned by hydrothermal treatment (HT) in term of the elevation of dewaterability. Higher hydrothermal temperature tended to enhance the dewaterability of SS rather than DS, which was supported by the variation of their physicochemical properties (including water distribution, bonding energy, extracellular polymeric substance (EPS), particles size, acid functional groups and zeta potential in this study). In addition, the changes in surface morphology suggested that the reverse effect of HT on sludge dewaterability was mainly due to their dewatering behavior. For SS, the destruction of EPS structure leaded to the release of bound water, thereby strengthening sludge dewatering. Conversely, "Bridging effect" generated by lignocellulose in DS was beneficial for sludge dewatering; however, the increasing hydrothermal temperature degraded part of lignocellulose and weakened "bridging effect", finally resulting in worse dewaterability of DS.

Relevance between chemical structure and pyrolysis behavior of palm kernel shell lignin.

Palm kernel shell (PKS) lignin obtained by enzymatic/mild acid hydrolysis (EMAL) was thoroughly elucidated by FTIR (fourier transform infrared), 13C-1H 2D-NMR (nuclear magnetic resonance), quantitative 31P NMR combined with DFRC (derivatization followed by reductive cleavage), and Py-GC/MS (pyrolysis-gas chromatography/mass spectrometry) with and without TMAH (tetramethylammonium hydroxide). Pyrolysis behavior was then characterized by TG-FTIR-MS (thermo-gravimetric-FTIR-mass spectrometry) and Py-GC/MS. The PKS lignin is demonstrated to be a p-hydroxyphenyl-guaiacyl-syringyl (H-G-S) lignin with abundances of p-hydrobenzoates and low S/G ratio of 0.15. 2D-NMR indicated that the main substructures are ß-O-4-ethers (~85%), and 31P NMR/DFRC quantified the total ß-O-4 content of 2295µmol/g. Py-GC/MS with and without TMAH confirmed that phenol mainly originated from p-hydroxybenzoates units. Thermal-stability, evolution behavior of typical volatiles, and selectivity of phenolic compounds (H-, G-, S-, C-type) during PKS lignin pyrolysis were explored. Relationship between chemical structure and pyrolysis behavior are also obtained. This work will provide a deep insight to the effective utilization of PKS.

Comparative evaluation of biomass power generation systems in China using hybrid life cycle inventory analysis.

There has been a rapid growth in using agricultural residues as an energy source to generate electricity in China. Biomass power generation (BPG) systems may vary significantly in technology, scale, and feedstock and consequently in their performances. A comparative evaluation of five typical BPG systems has been conducted in this study through a hybrid life cycle inventory (LCI) approach. Results show that requirements of fossil energy savings, and greenhouse gas (GHG) emission reductions, as well as emission reductions of SO2 and NOx, can be best met by the BPG systems. The cofiring systems were found to behave better than the biomass-only fired system and the biomass gasification systems in terms of energy savings and GHG emission reductions. Comparing with results of conventional process-base LCI, an important aspect to note is the significant contribution of infrastructure, equipment, and maintenance of the plant, which require the input of various types of materials, fuels, services, and the consequent GHG emissions. The results demonstrate characteristics and differences of BPG systems and help identify critical opportunities for biomass power development in China.