The implementation and management of wastewater treatment facilities have become an unavoidable process for sustainability in urban and suburban areas, such as industrial complexes, academic campuses, tourism centers, or extensive agricultural enterprises. Apart from the obvious contribution of these plants to the natural and living environments, these plants naturally help complying with environmental obligations, as related legal frameworks are becoming increasingly well controlled. However, the initiation and operational costs of these facilities might cause significant financial burdens due to the use of substantial human, material, and electrical energy resources. Being the site considered as a case study in this chapter, the Eskişehir Organized Industrial Zone’s treatment plant demanded more than 700,000 kWh of electric energy, costing over 350,000 Turkish Lira (26.000 USD equivalent as of Dec. 2021) for its energy needs, even before the serious escalation of expenses in 2022. This example, along with several other well-known cases, reveals the significance of renewable energy sources for the cost-effective and sustainable operation of these treatment plants. The cost-efficiency and sustainability of renewable energy use in wastewater treatment plants can be investigated from a financial, as well as an environmental perspective, as national electric production is still predominantly fuel-based, and irresponsible electric utilization could also contribute adversely to the total carbon footprint. This study presents a detailed case study that investigates the potential for renewable energy integration and the determination of the necessary capacity to fulfill the energy requirements of the wastewater treatment facility located in the Eskişehir Organized Industrial Zone.