4. A Refined Assessment Methodology for Wastewater Treatment Alternatives

The environmental quality of receiving waters will no longer be the sole objective of sustained management in future wastewater treatment. In addition to the protection of water resources and environments, considerable attention must be paid to other resources, such as energy and nutrient resources, for long-term sustained development. It is certain that the reduction of the energy consumption and greenhouse gas (GHG) emissions and resource recovery will become key focus areas in the development of new wastewater treatment technologies and processes in the future. The exploration of methods to construct novel ensemble-type wastewater treatment technologies and processes aiming at energy conservation, reduced carbon emissions, and resource recovery based on existing technologies and processes is the future trend in the development of the wastewater industry. As described in Sect. 2.​3, comprehensive assessment systems of wastewater treatment processes were established based on the assurance of environmental benefits such as the water quality. In Chap. 3, the sources and key links of the environmental impact of typical wastewater treatment processes were preliminarily analyzed from the life cycle perspective. However, there is a lack of consideration of the recovery and utilization of usable materials in wastewater and sludge and relevant scenario settings and analysis. Therefore, regardless of the research and development of new technologies and new processes in the future or the upgrade and reconstruction of existing processes, a scientific, systematic, and comprehensive wastewater treatment assessment system is required. Such a system should consider the technological levels of existing wastewater treatment processes and the main environmental effects of the wastewater treatment and resource recovery potential of materials produced during the treatment.