As wastewater professionals committed to serving our communities, we all invest valuable time keeping up to date on the latest advances in our industry. And while it can be interesting to follow the latest technical advances made by WWTP operators in larger cities or regions, some of these innovations do not always make economic sense for administrators who manage smaller networks. The buzzworthy topic of digital twins is an excellent example of an industry trend that, at first glance, seems to be to be both very complex and expensive. But is this really the case?

What is a “digital twin” in the Wastewater Industry?

There are many definitions of what a digital twin is and this is because the concept can be applied in different ways across various industries. A very simple definition is that a digital twin is the virtual – or digital - representation of the properties and functionality of a physical object or system. The benefit of creating a virtual copy of an object or system is that any modifications – such as those made to individual components or in adjustments to modes of operation - can be quickly tested and validated without impacting real-world operations. The fidelity of the digital twin to its physical counterpart is, generally speaking, a function of three core elements: the availability of real-time data, the complexity of the digital model used to represent the object, and the analytics or logic used to mirror or evaluate the object or system’s function. One can quickly see how adopting this approach leads to reduced risk and lower investment costs. But what have been the benefits so far for the wastewater industry?

We are currently witnessing the industry’s transformation from just capturing data and presenting it to an operator for analysis and action (e.g. dashboards) to a period where operators can now use sophisticated software to model and predict potential outcomes based on the collection of data from different sources. Naturally, the concept of a digital twin is the logical extension of this technological progression. To date, several larger drinking water utilities have used digital twins to help them solve large scale production and distribution problems, improve operator training and advance purification techniques. On the wastewater side, most digital twin platforms have been developed to evaluate processes within the WWTP and are used to asses the best ways to increase nutrient removal from sludge, reduce the volume of chemicals used in treatment, and to decrease energy consumption.

For smaller organizations with a limited budget, all of this may all seem interesting but financially and technically out of reach. However, if you have a SCADA system and have - at one time or another - engaged an engineering firm to model some part of your production or distribution capabilities using a modelling software like SWMM, then you are actually much farther down the path of creating a digital twin than you may realize.

Why Should You Consider a Digital Twin Project?

During the last two or three years many in the water industry have committed significant resources to help answer this question. Members of the SWAN (Smart Water Networks Forum) have developed a Digital Twin Working group which has developed a model digital twin architecture graphic. Many industry thought leaders, such as Mr. Colby Manwaring at Innovyze, have written some excellent articles about how (and when) a digital twin project should be implemented. His article makes the important point that there is no “standard”, one-size-fits-all digital twin platform and that each organization, no matter its size, can build a version of a digital twin that meets their clearly defined objectives. Here at RTC4Water, our focus has been using a variant of the digital twin concept to optimize the performance of small to medium-sized drinking water and wastewater networks. Our clients, all of whom are small to medium-sized operators have benefited from this approach in several ways. For example, clients were easily able to:

• Evaluate the need to build expensive new basins by analyzing current sewer network storage performance
• Evaluate different pumping strategies with a goal to reduce electricity costs

From Digital Twin to Fully Autonomous, Predictive Control of Networked Resources

A digital twin is very useful for analysis and evaluation, but it is not the same as implementing a fully autonomous, real-time control system. For decades, the energy and gas industries have used technologies like Model Predictive Control to fully automate their production operations using on real-time data. One of the advantages of this platform is the removal of the human operator from the equation while still maintaining strict limits on performance and outcomes. Much like the digital twin, Model Predictive Control uses real-time data introduced into a mathematical model representing a dynamic system. When RTC4Water works with a client to optimize the flow and storage in their wastewater network, we follow many of the same steps used to create a digital twin. However, instead of establishing a large and complicated data repository representing an entire system, we limit our work to only using the minimal amount of data necessary to achieve the desired result. In this way, administrators of smaller networks can benefit from some of the advantages provided by a digital twin, but without having to fund, or manage, a large-scale program designed to mimic all aspects of their operations. For example, a very inexpensive study performed for one of our clients clearly demonstrated how the use of a digital twin and Model Predictive Control-based technologies can be used to reduce sewer network construction costs.

How to Get Started

When we begin working on a project with clients, the most important first step is to fully understand their objectives and the needs of the people they serve. Before starting any project, we typically recommend that our clients:

• Start by clearly defining one or two areas of operations to be optimized and which parameters should be studied – a digital twin can always “grow” later as new information is discovered and needs change
• Assess the depth and robustness of their data collection capabilities (data quality, frequency and relevance)
• Define a small, foundational project which has a clear, measurable goal and which can visibly demonstrate value for their stakeholders and community

Is your syndicate or city interested in reducing the combined sewer overflows without building bigger basins? Do you wish to find ways to use your existing sewer network infrastructure more efficiently? Please contact our team for more information.