Demand response through reject water scheduling in water resource recovery facilities: A demonstration with BSM2

The objective of this paper is to determine the importance of integrating peak demand mitigation and future energy pricing structures for process modelling of conventional water resource recovery facilities (WRRFs) when evaluating energy cost and control strategies. The well-established benchmark simulation model (BSM2) is used to monitor energy usage, and a detailed holistic study of different flow streams is performed in order to establish potential opportunities for flexible control of WRRF energy demand. Secondly, a detailed framework is introduced to optimize scheduling control strategies for the reject water stream while considering peak electricity demand avoidance as well as completing a comprehensive energy cost model based on current and anticipated future energy tariff structures. The reject water scheduling strategies, without other active controls (e.g. aeration), revealed 63.4% average peak demand mitigation and €10,755 cumulative annual energy cost savings on a 100k population equivalent WRRF without a deterioration in effluent quality. Analysis of different reject water scheduling control strategies shows that reject water scheduling can be an effective tool for energy cost optimisation under alternative electricity tariff structures. These strategies also deliver electricity peak demand mitigation.