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The characteristics and gas product properties of pyrolyzing sewage sludge were determined, aiming to utilize efficiently the waste for energy recovery. The pyrolysis of two predried sludge materials (S1 and S2) was conducted in a thermogravimetry analyzer (TGA). It was found that the pyrolysis mainly occurred at about 150–550 °C, with two and one reaction stages found respectively for S1 and S2. Using the global reaction kinetic model, the activation energy was calculated at ∼30 kJ mol−1 in the first reaction stage for all the selected heating rates, and the pre-exponential factors increased with the increasing heating rate. The kinetic parameters calculated explained well the pyrolysis characteristics observed. In the meantime, the gas products released under different pyrolysis conditions were analyzed online using Fourier transform infrared (FTIR) spectroscopy; the results showed that the gas composition was highly dependent on temperature, and the releasing of the gas species was consistent with the weight loss of sludge in pyrolysis. Thermodynamic simulation using Outokumpu HSC Chemistry version 4.1 was conducted to predict the thermodynamically predominant gas species at different temperatures. A further analysis by dividing the whole pyrolysis of sludge into 5 temperature regions revealed preliminarily the sludge pyrolysis mechanisms. This fundamental study provides a basic insight into the sludge pyrolysis, which would benefit the efficient utilization of sewage sludge as an energy source.

Biochar (BC) derived from bamboo pyrolysis and its modified forms were treated with chemical methods (oxidation either by KMnO 4 or HNO 3 and base treatment with NaOH) and heat method. BC and modified BCs were investigated as adsorbents for target component (furfural) removal from aqueous solution. The samples were characterized to assess the effects of different treatments on structure and surface chemistry of BCs. The results show that chemical treatments increase the hydrophilicity of BC, whereas heat treatment causes the opposite effect. Oxidation treatment leads to the introduction of a large number of acidic functional groups on the BC surface, with HNO 3 being more effective than KMnO 4 . In contrast, NaOH treatment and heat treatment increase the basicity of BC. Pore structures of BCs are also significantly changed after these modifications. Furfural adsorption capacity of BCs increases with the increase of basic surface group content, which can be attributed to the enhancement of dispersion interactions. The higher hydrophilicity of BC is, the lower the furfural uptake capacity is. The heat-treated samples demonstrate the highest capacity for furfural adsorption, with a removal efficiency of up to 100% at a furfural concentration of 10 g/L. However, all chemical treatments reduce furfural removal capacity. The Ho's pseudosecond-order model, intraparticle diffusion model, and Langmuir isotherm fit the adsorption data well.