A Review on the Trade-offs between stricter Discharge Limits and Energy Efficiency in Wastewater Treatment Plants

Wastewater treatment plants are often challenged to comply with stricter effluent discharge limits while minimizing energy demand, raising concerns over the trade-off between meeting water quality goals and environmental sustainability. This study investigates how stricter effluent regulation, combined with factors such as plant capacity, pollutant load, and treatment processes, affects energy consumption. Findings reveal that stricter discharge standards increase energy demand, primarily due to intensified biological treatment, extended aeration, and greater chemical usage; however, existing research, largely focuses on China. Rarely are the governing regulations and levels of compliance detailed in existing research, limiting insights into how applied policy shapes WWTP performance and environmental impact. Guiding sustainable regulation requires future research to couple regulatory context with detailed energy accounting data. Without such integration, policies may advance water quality goals while undermining climate objectives, threatening the sector’s long-term sustainability.