<![CDATA[Wastewater Treatment Plants (WWTPs) are among the most energy-intensive infrastructures in environmental management, with substantial energy consumption occurring in pumping, aeration, sludge treatment, and auxiliary operations. Although many studies have addressed energy-efficiency improvement, less attention has been given to systematically identifying non-value-added energy consumption from a lean management perspective. This study aims to synthesize research on energy waste in WWTPs, identify major operational sources of energy waste, examine the application of lean management and Value Stream Mapping (VSM) principles, identify emerging digital technologies, and develop a conceptual lean-based Energy Waste Mapping Framework. The study combines bibliometric analysis and a PRISMA-based systematic literature review using a revised Scopus search strategy that requires the simultaneous presence of WWTP, energy, and lean/VSM concepts. The bibliometric component is used to characterize research trends, thematic development, and emerging technologies, while thematic synthesis is used to identify operational energy-waste sources and classify them according to lean waste principles. The literature indicates that aeration, pumping, sludge handling, recirculation, and inefficient equipment operation are recurrent sources of energy waste. The identified wastes can be classified into five categories: waiting, overprocessing, transportation, motion, and overproduction. These findings provide the basis for a conceptual Energy Waste Mapping Framework that adapts VSM principles to WWTP process analysis. The framework is conceptual and requires validation through full-scale WWTP case studies before quantitative claims about energy savings can be made.]]>
