Waste treatment and optimal degree of pollution abatement

Environmental impacts of industrial production processes are usually estima ted by considering the emissions leaving the process. These emissions are o ften reduced using abatement processes, such as wastewater treatment techno logies, 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 poss ibility that some waste streams may be over treated. In other words, indust ry 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 en vironmental point of view. The work examines trade-offs in abatement proces ses between higher inputs (energy consumption and raw material) and lower d ischarge quantities (pollutant flow). As a result, an optimal degree of pol lution abatement (ODPA), at which environmental impact is minimized, is ide ntified. This value could act as a guideline to legislators who are setting discharge limits and to chemical engineers with waste discharge responsibi lities. Case studies on two different abatement technologies, steam strippi ng and pervaporation, are presented to illustrate this framework.