This study investigates the integration of heat exchangers within grease traps (GT) to enhance the removal efficiency of fats, oils, and grease (FOG) in wastewater treatment systems and promote energy efficiency in the heating of water. While traditional grease traps are effective, their performance can be further optimized by harnessing thermal energy embedded in wastewater to solidify and separate FOG. By lowering the temperature of wastewater, the heat exchanger promotes FOG retention within the trap, thereby reducing its discharge into sewer systems. Experimental findings reveal a substantial increase in FOG removal efficiency, up to 25%, with the incorporation of heat exchanger (HX) technology. Moreover, system efficiency is enhanced through the optimization of operational parameters. Notably, when the mass flow rate of the heat exchanger (ṁH) surpasses that of the GT (ṁG), heat recovery sees a notable increase, exceeding 50%. This enhancement proves particularly advantageous in colder weather conditions, where the temperature differential between wastewater and the surrounding environment is more pronounced. Additionally, this study estimates the energy savings achieved through minimum and maximum heat recovery by a copper HX in displacing use common fuels such as electricity, oil, and gas, in water heating over an 8-h operation period annually. It considers both the average prices and greenhouse gas (GHG) emission costs associated with each fuel type. The minimum and maximum recovered heat values are 0.7 and 1.3 kW, respectively. This translates to energy savings and reductions in GHG emissions ranging from €240 to €1000 per year.