Dr. Shiqiang (Nick) Zou is an assistant professor at the Department of Civil and Environmental Engineering at Auburn University. His research focuses on developing electrified solutions to transform resource-intensive wastewater management into a resource-supplying hub. Prior to joining Auburn, he completed his postdoctoral training at Stanford University and received his Ph.D. in Civil Engineering from Virginia Tech.

Thermal energy represents a significant portion of energy potential in municipal wastewater and may be recovered as electricity by a thermoelectric generator (TEG). Converting heat to all-purpose electricity by TEG has been demonstrated with large heat gradients, but its application in waste heat recovery from wastewater has not been well evaluated. In this project, we constructed a lab-scale Bi2Te3-based waste heat recovery system to generate electricity from a low temperature gradient through a combination of experiments and mathematical modeling. With an external resistance of 7.8 Ω and a water (hot side) flow rate of 75 mL/min, we achieved a maximum normalized energy recovery of 4.5 × 10−4 kWh/m3 under a 2.8 °C temperature gradient (ΔT). Model simulation indicated a boost in both power output and energy conversion efficiency from 0.76 mW and 0.13% at ΔT = 2.8 °C to 61.83 mW and 1.15% at ΔT = 25 °C. Based on the two-year water/air temperature data obtained from a local Wastewater Treatment Plant, we estimated an annual energy generation of 1094 to 70,986 kWh for this 8-MGD plant. Our results reveal a potential for TEG-based electricity generation from low-grade heat for on-site energy compensation in wastewater treatment plants.