Mohammad Alrbai, Sameer Al-Dahidi, Hussein Alahmer, Bashar Shboul, Bilal Rinchi, Mosa Abusorra, Loiy Al-Ghussain, Hassan Hayajneh, Ali Alahmer
This study investigates the recovery and utilization of waste heat from biogas generators in wastewater treatment facilities for sustainable cooling applications. The As-Samra Wastewater Treatment Plant in Jordan was selected as a case study, where waste heat from biogas-fueled generators was used to drive a single-stage absorption chiller for building cooling. The objective was to evaluate the technical, economic, and environmental performance of the proposed system through integrated modeling and optimization. Thermodynamic modeling and dynamic simulations were conducted in TRNSYS® and Aspen Plus® using real operational data. A parametric analysis was performed to examine the influence of biogas flow rate, exhaust gas temperature, and solution circulation rate on system performance and cost. To enhance system performance, a hybrid optimization framework combining the Multi-Objective Cheetah Optimizer and Random Forest Regression was developed and compared with Particle Swarm Optimization and Grey Wolf Optimization. The optimized configuration achieved a coefficient of performance of 0.942 with a reduced circulation ratio of 1.52. The levelized cost of cooling ranged from 0.0175 to 0.0178 USD/kWhₜₕ, nearly half the cost of conventional cooling systems. Economic analysis indicated positive Net Present Values of 0.315–0.330 million USD, benefit–cost ratios greater than unity, and payback periods of 4.1–4.25 years. In addition, the system is estimated to reduce annual CO₂ emissions by 406–421 tons. These results demonstrate the potential of integrating waste heat recovery and machine learning–based optimization to improve the sustainability of wastewater treatment facilities