The pyrolysis characteristics and kinetics of pre-dried dewatered sewage sludge under different heating rates (10, 20, and 30 °C/min) were investigated by thermogravimetric analyzer-fourier transform infrared analysis (TG-FTIR) and differential scanning calorimetry (DSC), and a heated tubular reactor. The thermal analysis results showed that four weight loss zones (<165, 165–400, 400–600, and >600 °C) were observed in TG curve, and a higher heating rate led to the increase of the maximum devolatilization rate and the higher temperature corresponding to the peak. The activation energy of different heating rate (10, 20, and 30 °C/min) was 70.0, 60.6 and 65.0 kJ/mol, respectively. The FTIR analysis of gaseous products indicated the concentrations of CO₂ and CO increased steadily with the increased heating rate, while the concentration of CH₄ first increased then decreased. Moreover, the yield of gaseous products and bio-oil increased with the increasing of the heating rate. Finally, the surface structure of chars and the chemical properties of bio-oil obtained were characterized using nitrogen adsorption, scanning electron microscopy, elemental analysis and gas chromatography–mass spectrometry. Overall, the results highlighted that pre-dried dewatered sewage sludge can be effectively converted into biofuel and porous material.

Deltas are widely threatened by sediment starvation and climate change. Erosion potential is an important indicator of delta vulnerability. Here, we investigate the erosion potential of the Yangtze Delta. We found that over the past half century the Yangtze's sediment discharge has decreased by 80% due to the construction of >50,000 dams and soil conservation, whereas the wind speed and wave height in the delta region have increased by 5-7%, and the sea level has risen at a rate of 3 mm/yr. According to hydrodynamic measurements and analyses of seabed sediments, the period when bed shear stress due to combined current-wave action under normal weather conditions exceeds the critical bed shear stress for erosion (τ_cr) accounts for 63% of the total observed period on average and can reach 100% during peak storms. This explains why net erosion has occurred in some areas of the subaqueous delta. We also found that the increase with depth of τ_cr is very gradual in the uppermost several metres of the depositional sequence. We therefore expect that the Yangtze subaqueous delta will experience continuous erosion under sediment starvation and climate change in the next decades of this century or even a few centuries.