Technical and financial evaluation of an emerging thermochemical technology for sustainable management of municipal wastewater sludge

Abstract

The management of municipal wastewater sludge is a significant challenge for wastewater management, particularly the need to manage and dispose of the sludge in an environmentally friendly and sustainable manner. The emergence of stricter regulations regarding landfill disposal of wastewater sludge necessitates the need for alternative options for municipal wastewater sludge management, with thermochemical technologies potentially contributing towards achieving carbon neutrality goals and fostering sustainable development. This study sought to address these challenges through a technical and financial evaluation of a pilot-scale emerging thermochemical technology, the enhanced hydrothermal polymerization to provide adequate understanding of the technology's feasibility regarding its application for municipal wastewater sludge volarization into a multi-use hydrochar. The study findings indicated that the enhanced hydrothermal polymerization-generated hydrochar exhibited significant energy content compared to wastewater sludge, suggesting the potential use of the hydrochar as an energy source. The preliminary designs of a full-scale greenfield installation and retrofit processing 50 t/d and 35 t/d dry sludge, respectively, were evaluated to be technically feasible. Furthermore, on the basis of preliminary designs, the enhanced hydrothermal polymerization technology was determined to be the most financially feasible option, also offering other unique advantages over well-established technologies currently used within municipal wastewater services.