Application of sludge-based biochar generated by pyrolysis: A mini review

The production of sludge is increasing with the rapid development of wastewater treatment. However, to sludge disposal, the restriction of landfill and the hazard of incineration fly ash show that it is imperative to develop a suitable technology to solve the sludge problem. As an emerging sludge treatment technology, pyrolysis has the advantages of reduction, stabilization, harmlessness, and recycling to sludge. In addition, high-value utilization can be made to the pyrolysis products, especially for sludge-based biochar. However, the performance of sludge-based biochar can be affected by many factors, thus it is essential to investigate its preparation conditions, existing problems, and potential applications. In view of this, this mini review firstly discusses the preparation and characterization methods of sludge-based biochar, and points out the preparation method of a novel sludge-based biochar that can remove large amounts of pollutants. Then the applications of sludge-based biochar such as adsorbents, soil conditioners, and catalyst carriers, are also introduced, respectively. Meanwhile, the existing problems during the applications of sludge-based biochar are pointed out. Finally, from the perspective of preparation and application of sludge-based biochar, the research emphases in future are proposed.