Renewable energy of wastewater heat recovery.

Wastewater heat recovery (HR) is one of the renewable energy sources. The associated harmful environmental, health, and social effects of traditional biomass, fossil fuel, and other polluted sources have enhanced the growing interest in the search for an alternate cleaner energy source globally. The major objective of this study is to develop a model to assess the impacts of wastewater flow (WF), the temperature of wastewater (TW), and internal temperature in sewer pipes (TA) on the performance of HR. Sanitary sewer networks in Karbala city of Iraq were chosen as a case study in the present research. Statistical and physically based models such as the storm water management model (SWMM), multiple-linear regression (MLR), and structural equation model (SEM) were used for this purpose. The model outputs were analyzed to assess the performance of HR in the context of changing WF, TW, and TA. The results showed that the total amount of HR from wastewater in Karbala city center during the 70 days was 136,000 Mw. The study clearly showed that WF in Karbala played a major role in HR. Basically, the heat from wastewater is CO2-free and represents a significant opportunity for the energy transition in the heating market.