Waste treatment and optimal degree of pollution abatement

Environmental impacts of industrial production processes are usually estimated by considering the emissions leaving the process. These emissions are often reduced using abatement processes, such as wastewater treatment technologies, in the belief that reducing emissions will reduce the environmental impact. Typical legislation focuses on reducing discharge levels, without considering the impact on the environment of the additional inputs required by the abatement process to achieve this reduction. This leads to the possibility that some waste streams may be over treated. In other words, industry might be devoting increased resources to reducing discharges and at the same time be worsening the environment. This paper presents a framework for the analysis of wastewater treatment technologies from art economic and environmental point of view. The work examines trade-offs in abatement processes between higher inputs (energy consumption and raw material) and lower discharge quantities (pollutant flow). As a result, an optimal degree of pollution abatement (ODPA), at which environmental impact is minimized, is identified. This value could act as a guideline to legislators who are setting discharge limits and to chemical engineers with waste discharge responsibilities. Case studies on two different abatement technologies, steam stripping and pervaporation, are presented to illustrate this framework.