Simulation for sustainable design of wastewater treatment plants

The water and wastewater industry in Sweden is facing major investments of SEK 2-3 billions per year for construction of wastewater treatment plants (WWTPs).

The population is growing as are the demands on degree of treatment, resource and cost efficiency as well as reduction of CO2 emissions.Today´s WWTPs are dimensioned based on rules of thumb with non-transparent safety factors.

This means that the dimensioning becomes subjective and difficult to understand, which involves an increased risk that the new treatment plants will not meet the requirements during the entire life cycle.

Innovative data collection technologies and new methodologies for applying existing dynamic process models have great potential to improve the dimensioning process.Process modelling and simulation of treatment plants is a mature digital technology that can be used for, among other things, life cycle analysis, development and testing of control strategies and for training.

Despite the high degree of maturity, it is unusual that the simulators are used for dimensioning.

The most important reason for this is that process models are developed to describe reality without safety factors at the same time as some degree of redundancy is needed in the dimensioned WWTP.

A clear challenge with model-based dimensioning is then that all assumptions that need to be made must be expressed explicitly and transparently in the form of time series and scenarios.

Today, there is no comprehensive method for how these are to be simulated.We believe that increased use of dynamic models and simulation for dimensioning treatment plants leads to more efficient treatment processes and operations.

To accelerate this approach, it is important that end-users to a greater extent include simulation while setting requirements for suppliers and consultants, which in turn requires increased competence in process modelling.The purpose of the project is therefore to contribute to the industry´s digital transformation through i) raising knowledge in process modelling and ii) developing and innovating new methods for model-based dimensioning.The project uses the Uppsala water (UVAB) facility as a full-scale example as they are currently facing a large reconstruction project.

The organization is interested in building competence in process modelling, something they lack today.There are a few organizations and people in the water and wastewater industry with experience of process modelling and it can be lonely to be a forerunner, especially when you possess a unique competence.

As part of bringing about an increase in knowledge in the industry, the project therefore wants to gather these people and create a forum to strengthen their development.

This is done through practical exchange of experience and problem solving for process modelling as a tool for dimensioning.The project results in an increased digital maturity of the project´s critical mass of need owners as well as a full-scale demonstration of the benefits of model-based dimensioning as an optimization and requirements-setting tool.

A general and scalable method for model-based dimensioning is being developed, where standardized data analysis of motion and load data are central components for creating transparent safety margins.The effect of the project is that the need owners utilize digital tools (data-driven analysis, process modelling and developed methods) to procure and operate smart and sustainable WWTPs.

The in-depth understanding of how resilience can be achieved by model-based dimensioning leads to an cost-effective increased environmental benefit throughout the life cycle.

The full-scale technology demonstration strengthens the industry´s confidence in process modelling as an effective tool for sustainable dimensioning, which will be a driving force for the industry´s digital transformation.