Effects of pyrolysis temperature and addition proportions of corncob on the distribution of products and potential energy recovery during the preparation of sludge activated carbon

Abstract

The potential energy recovery during sludge activated carbon (SAC) preparation by co-pyrolysis of sewage sludge and biomass has recently gained significant attention. This study firstly evaluated the distribution of pyrolysis products including SAC, oils and gases during sludge pyrolysis at different temperatures (400 °C–800 °C) and corncob addition proportions (0–50%, w/w). The results demonstrated that with the increase of pyrolysis temperature, yield of SAC declined dramatically, while yields of pyrolysis oils and gases increased. With increasing addition of corncob, the yields of SAC and pyrolysis oils declined slightly, while the yield of gases generally increased. Then, the potential energy recovery during sludge pyrolysis was calculated, and the highest energy recovery value was 10.21 kJ/g achieved at 800 °C and 50% corncob addition. However, higher pyrolysis temperature over 600 °C resulted in lower yield and iodine adsorption capacity of SAC. Therefore, the suitable conditions were suggested to be at 600 °C with 50% corncob addition considering both adsorption performance of SAC and potential energy recovery efficiency.