To improve the performance of a wastewater treatment plant, various control strategies can be implemented (e.g. controlling the dissolved oxygen and/or nitrate level in the bioreactors). But before adapting a specific control strategy, computer simulations can first be performed to determine which strategy would best optimize the wastewater treatment plant (WWTP) performance in terms of effluent quality, operational costs, or any other applicable evaluation criteria. An objective comparison of different control strategies can be performed through the use of a ‘benchmark’.
The International Water Association Task Group on Benchmarking of Control Strategies for Wastewater Treatment Plants has developed the Benchmark Simulation Models (BSM1 and BSM2). The BSM1 plant consists of a five-compartment biological reactor and a secondary settler. It enables an unbiased evaluation of activated sludge control strategies related to organic (C) and nitrogen (N) removal. As a result of the interest from the scientific community and because of a number of limitations identified in that model, it was extended and developed into BSM2. The latter model includes full treatment of both water and sludge (by anaerobic digestion) with primary settling, sludge thickening and dewatering.
The success of both models is demonstrated by more than 500 papers in international journals and conferences on work related to the BSMs, the use of the model in various research groups around the world and its inclusion in various commercial WWTP simulator packages (e.g. GPS-X™, SIMBA®, WEST®).
Two PhD students at IEA are further extending the BSM2 ‘within-the-fence’ to include other significant processes within the wastewater treatment plant and ‘outside-the-fence’ to take into account the whole urban wastewater system including catchment, sewers and recipient.