Abstract:
An important requirement of wastewater treatment plants (WWTPs) is compliance withthe local regulations on effluent discharge, which are going to become more stringent in the future.The operation of WWTPs exhibits a trade-off between operational cost and effluent quality, whichprovides a scope for optimization. Process optimization is usually done by optimizing a model of theprocess. However, due to inevitable plant-model mismatch, the computed optimal solution is usuallynot optimal for the plant. This study represents the first attempt to handle plant-model mismatchvia constraint adaptation (CA) for the real-time optimization of WWTPs. In this simulation study,the "plant" is a model adopted from the BSM1 benchmark, while a reduced-order "model" is usedfor making predictions and computing the optimal inputs. A first implementation uses steady-statemeasurements of the plant constraints to adjust the model in the optimization framework. A fast CAtechnique is also proposed, which adjusts the model using transient measurements. It is observedthat, even in the presence of significant plant-model mismatch, the two proposed techniques are ableto meet the active plant constraints. These techniques are found to reduce the pumping and aerationenergy by 20%, as compared to that adopted in BSM1.