This special issue gathers papers in revised form that have been originally presented at MathMod 2006 in Vienna in the special session dedicated to the modelling and control of sequencing batch reactors (SBRs). These papers present the results that have been obtained within the framework of an EC project (Efficient Operation of Urban Wastewater Treatment Plants) whose acronym was EOLI. The project has been financed in the 6th framework programme of the EC within the programme INCO-DEV (Confirming the International Role of Community Research, Research for Development). The project gathered eight partners: five from Europe and three from Latin America. Among the European partners, four partners were from the academic and research world (the CESAME, Université catholique de Louvain, Louvain-la-Neuve, Belgium (coordinator); the LBE-INRA, Narbonne, France; Gradient, UTC, Compiègne, France; POLIMI, Milano, Italy) and one SME (SPES, Fabriano, Italy). The three Latin-American partners came from universities (UNAM, Mexico City, Mexico; UU, Montevideo, Uruguay) and from industry (IB-Tech). The objective of the EOLI project was to design a low-cost, modular and reliable monitoring and control system for wastewater treatment process dedicated to the treatment of wastewater from urban settlements. SBRs have been considered within the project because, in terms of investment and operation costs, process stability, and operation reliability, they are better than the conventional continuous activated sludge process.
The special issue contains six contributions that are distributed as follows. The first paper presents the experimental facilities (two in Europe and two in Latin America) and summarizes the experiments that have been performed in a first step mainly for modelling. The second paper provides the modelling and identification results obtained from the experimental data, as well as results of the software sensors that have designed to provide online estimates of the unmeasured key process variables. The third paper is the essential complement of the second part of the preceding one: it presents the results obtained within the activity of the project dedicated to the development of hardware sensors for the online monitoring of SBRs, mainly based on set-point titration and UV spectrophotometry. The fourth paper presents the results of the next brick in the project activities: the control of the process. In the present instance, optimal control based strategies have been developed and applied with different perspectives depending on the type of the SBRs considered. The fifth paper then presents the last important item of the complete system, the FDI and diagnosis tools developed within the EOLI project for SBRs. Finally, the sixth paper presents the system that integrates the different bricks developed within the project and which constitutes the complete supervision system of the EOLI project.