A linguistic analysis of energy terminology in the wastewater literature.

Recent wastewater treatment research has focused on technologies that can recover resources such as energy from the influent waste stream. Many unrelated studies have introduced or used energy-related terms to describe changes to wastewater treatment plant energy balances based on these technological innovations. Unfortunately, these wastewater energy-related terms are not well defined in the literature, with many used interchangeably and/or inconsistently. To address this shortcoming, this study (1) identified and defined the most prominent energy-related terms in academic literature, (2) proposed a classification schema, and (3) explored trends in term usage over time. Energy-related terms identified from the literature were defined and classified based on the term's functional role in the context of wastewater treatment plant energy use. Specifically, each term was classified as a wastewater treatment plant's long-term energy 'state', a descriptive short-term energy 'condition' at the plant, or an energy 'mechanism' that drives a plant from one state to another. The trend analysis concluded that the development of energy-related wastewater literature has generally outpaced the baseline rate of academic publishing in all fields. The results of this study can ensure clear communication between actors in the wastewater treatment sector by standardizing definitions for energy-related terms.