Utilization of Hydro-Turbines in Wastewater Treatment Plants (WWTPs)

Wastewater treatment plants (WWTPs) are a significant energy consumer, yet there are several opportunities of implementing on-site power generation systems. Within the treatment process, the high flow rate of effluent is produced and discharged to a nearby water body by gravity. Thus, hydro turbines can be utilized to generate power in such application due to a difference in elevation and high flow rate. This paper presents a case study of introducing a hydro turbine in wastewater treatment plant in Wisconsin and evaluating the power output in addition to determining the energy savings. The wastewater treatment plant considered in this study has an effluent flow rate of 190 MGD (million gallons per day) and elevation difference of 3 meters (10 feet) between the final stage of treatment and the discharge point. Based on the aforementioned parameters; hubless rim-drive Kaplan type hydro turbine (RDT) is the optimal choice to be used in such application. The RDT is designed and optimized by using in-house code. A computational fluid dynamics (CFD) software is applied to evaluate the performance of the proposed model, and the system is simulated through HOMER software to validate the results generated by the CFD. The expected savings is estimated to be 1,564 MWh/year.