Optimization of objective functions for the design, control and operation of activated sludge processes

At present, in many countries, there exist very strict and legal specifications to regulate the quality of the water discharged from wastewater plants. They are basically influenced by factors like public health, environmental concerns and economics. Nevertheless, the world of wastewater treatment plants is very complex since a vast number of plants configurations and operation schemes are found in today's plants and no common basis for comparison exist. The only way to assess the costs of wastewater treatment plants quantitatively, is to relate the plant design, operation and control to economics, since the different aspects of wastewater treatment could be weighted in an objetive way and a mathematical optimal solution may be found. At this moment there exist no general consensus about the different costs aspects in these type of process. The paper tries to bring up a methodology to allow the comparison of plants, with different configurations, in terms of the costs associated to: building, control performance and operation.