Wastewater as a Source of Heat Energy

Abstract

AbstractTo counteract climate change, the application of renewable energy sources and their efficient use are of crucial importance. In this context, wastewater has also gained increased attention in recent years. For decades, wastewater treatment plants have applied heat from digester gas combustion to meet internal demands. However, wastewater can be considered as a renewable heat source throughout its cycle, from production to disposal. Domestic, industrial, and commercial wastewaters retain considerable amounts of thermal energy after being discharged into the sewage system. It is possible to recover this heat through technologies such as heat pumps and exchangers and reuse it to meet heating demands, among others. This chapter provides an overview of existing opportunities for wastewater heat recovery and its potential at different scales within the sewerage system, including at the level of wastewater treatment plants. A systematic review of the benefits and challenges of wastewater heat recovery is provided, taking into account not only technical aspects, but also economic and environmental ones. This study analyzes important parameters, such as the temperature and flow dynamics of the sewage system, the impacts of heat recovery on the environment, and the legal regulations involved. The existing gaps in the field of harnessing the heat energy contained in residual effluents are also identified. The potential of wastewater to supply clean energy on a scale ranging from buildings to large communities and districts will be analyzed, assessing the role of administrations and other stakeholders in taking advantage of the full potential of this valuable renewable heat source.