Analyzing Risk in Wastewater Process Design: Using Monte Carlo Simulation to Move Beyond Conventional Design Methods

Because there are many variables and uncertainties that can affect the performance of wastewater processes, conventional design methods, which analyze uncertainties in relative isolation, do not always provide an adequate analysis of the risks in a design, including their probability and sensitivity to other variables. A more robust risk analysis method for complex systems is modeling using a Monte Carlo simulator, which allows you to define design variables as probability distributions and generate multiple simulations with different sets of input variables. The Monte Carlo simulator produces a probability distribution for each outcome and the sensitivity of the outcome to the input variables. To achieve the best results, the Monte Carlo simulator should be used with a robust whole plant process simulator. Combining the two models allows you to evaluate risks throughout a wastewater treatment plant based on uncertainties in raw sewage characteristics, plant performance, and operational setpoints.