Current legislation for WWTP establishes stricter removal of organic matter and nutrients, especially nitrogen and phosphorus. Hence, new WWTPs must be designed and other already existing must be retrofitted to achieve the required discharge limits. Mathematical models allow a correct description of the processes observed in the WWTP and hence are a great help for these tasks. For instance, the IWA ASM2d is able to describe the behavior of the observed biological removal of COD, N and P in a common WWTP.
This research line proposes the use of ASM2d and other related models as a tool for the improvement and innovation of conventional processes of biological treatment in WWTP. Modelling, simulation and mathematical optimization techniques are widely used in this research line. Benchmarking criteria have been developed using single cost functions or multicriteria tools. Multicriteria techniques consider different factors as effluent quality, risk of microbiological separation problems or economic criteria. Single cost functions can take into account several criteria but transformed into a single cost function using different arbitrary weights. Both procedures give complementary characteristics and can be used depending on the study. Mathematical optimization using classical heuristic methods, direct search algorithms or Montecarlo techniques are used to optimise these criteria.
Three main topics appear in this research line:
- WWTP retrofitting for nutrient removal based on benchmarking techniques. Characterization of influent wastewater regarding model requirements. Model fit to full-scale WWTP data. Evaluation of WWTP modifications using mathematical optimization techniques and benchmarking criteria. Selection of the best configuration considering several criteria.
- Model based design of novel configurations for COD/N/P removal including bioaugmentation strategies, scale-up, removal efficiency optimization, economic feasibility, resilience and comparison to standard configurations.
- Model based design of new control strategies for municipal WWTPs with COD/N/P removal. Design and optimization of control structures by means of benchmarking tools and controller performance criteria. Selection of the best control and operational point considering different criteria.