Author Description

Wastewater collection systems, among the oldest features of urban infrastructure, are typically dedicated to collect and transport wastewater from users to water resource recovery facilities (WRRFs). Since the 1970s, wastewater engineers and scientists have come to understand that wastewater collection systems can bring benefits for urban water and energy networks, including thermal energy recovery and converting pipelines to bioreactors. However, there is little knowledge about the temporal and spatial changes of collection systems parameters that are important for these applications. Furthermore, the vast majority of existing studies of these applications have focused on laboratory or extremely small-scale systems; there have been few studies about beneficial applications associated with large-scale systems. The purpose of this study is to increase our understanding of how urban wastewater collection systems can bring potential benefits to urban water and energy systems. Models describing wastewater hydraulics, temperature, and water quality can provide valuable information to help evaluate thermal energy recovery and wastewater pretreatment feasibility. These kinds of models, and supporting data from a case study, were used in this study; sizes of the theoretical wastewater collection systems range from 2.6 L/s to 52 L/s, and the sample locations of the case study had flows ranging from 2.3 L/s to 24.5 L/s. A cost-benefit analysis of wastewater source heat pumps was used to evaluate the thermal energy recovery feasibility for different sizes of wastewater collection systems. Results show that the large collection system can support a large capacity heat pump system with a relatively low unit initial cost. Small collection systems have a slightly lower unit operating cost due to the relatively high wastewater temperature. When the heat pump system capacity design was based on the average available energy from the collection system, larger systems have lower paybac