Exergy analysis and environmental impact

Abstract

This chapter is concerned with the definition and application of exergy indexes to assess the performance of environmental impact mitigation technologies. These parameters are employed to evaluate the performance of air emission treatment systems, procedures to remediate contaminated sites, management of solid wastes, and technologies of wastewater treatment technologies. Initially it is proposed that the cumulative consumption of materials and utilities for construction and operation of environmental treatment systems can be quantified in terms of exergy. In addition, the exergy content of the emissions of a given production process, as well as the exergy of by-products of the treatment process, can be quantified to develop an exergy balance, focused on the treatment process. Thus, a methodology is described to compare different process alternatives in two situations: in the former the main task of the process is to eliminate the exergy content of a given emission, and in the latter the objective of the process is to maximize the utilization of the exergy content of a given emission. The environmental performance of wastewater treatment technologies is conducted by calculating the environmental exergy efficiency and complemented with the determination of the renewability exergy index. This approach is applied to compare three wastewater treatment plants based on biological (aerobic and anaerobic) and physicochemical processes.