Renovation of the WWTP hove.

The provision of reliable treatment has always been a priority in sanitary engineering. However, there is an ever-increasing pressure to meet desirable standards at reduced costs. This paper sets out a methodology to enhance the likelihood of a satisfactory allocation of the resources while providing reliable treatment. The procedure was gradually developed to optimise the massive capital investment of the Flemish Government to comply with the effluent standards set in the EU Directive 271/91. The methodology makes an extended use of dynamic modelling. To facilitate the identification and estimation of the uncertainty, a probabilistic Monte Carlo engine is coupled to the dynamic models. In doing so this approach provides a way of explicitly incorporating uncertainty and variability in the process analysis. The procedure is examined in an upgrade of a conventional WWTP towards stricter effluent norms on nutrients. The results suggest that the procedure can support the decision-making process under uncertainty conditions and enhance the likelihood of meeting effluent standards not entailing above-normal capital investments. The analysis led to reducing the capital investment by 43%, producing savings of more than 1.2 million Euros.