Exploring the potential of dynamic air supply models to evaluate control strategies: the experience at the Girona WRRF. Proceedings ICA2017
Abstract: A model-based treatment performance and energy audit of the Girona WRRF in Spain was conducted using advanced and fully dynamic air supply models. The focus of the study was on the aeration system, which represents 63% of the plant’s energy consumption. A dynamic model consisting of a process, a realistic controller, and a very detailed air supply model, was developed and calibrated to be used as the baseline for testing various scenarios. Results show that the implementation of an ammonia-based controller and a redistribution of the diffusers led to energy savings between 12 and 21%, depending on wastewater temperature. In addition, the model demonstrated that the current blower is too large, which causes an intermittent behaviour, endangering the equipment and shortening its life-time, plus limiting the minimum air-supply. The applied aeration system models enable engineers to identify bottle-necks by modelling equipment constraints (e.g. blower turn-down). Ignoring the air supply side in an assessment could result in an overestimation of energy savings or treatment performance and consequently in non-optimal control solutions or equipment selection.