Multi-objective optimization of large-size wastewater treatment plants operation and design

This paper deals with the multi-objective optimal control of a small-size wastewater treatment plant, where the excess sludge produced is incinerated for electricity production. The trade-offs between the treatment quality and operating costs are characterized. Emphasis is put on a proper formulation of the problem so as to get physically relevant solutions. Sludge incineration is shown to be quite profitable energetically, especially when a high nitrogen discharge is tolerated.