AUTHOR
Related Topics
Digital Twins
Wastewater Treatment
Energy Efficiency
Program Highlights
- >20 % less energy consumption for aeration
- Optimised plant operation led to a drastic reduction in peak energy consumption
- Savings of approx. 200,000 kWh/year, equivalent to about 50 fourperson households
- Forecasting models helped to control gas production depending on consumption
Stadtwerke Trier (SWT) operates the main wastewater treatment plant (WWTP) in Trier, with a capacity of 170,000 population equivalents. This facility was one of the largest energy consumers in the utility for many years. Although investments in energy-efficient technology significantly reduced this consumption, intelligent control was still needed to make the existing technology more efficient and even make plant operations’ energy self-sufficient.
THE CHALLENGE
Germany’s oldest city was therefore looking for an innovative system that would simultaneously streamline the energy requirements in biological processes, increase operational safety and improve the control of chemical use. Optimisation had to significantly reduce operating costs and close the energy cycle within the main wastewater treatment plant. This required coordinating energy consumption and production to prevent external energy purchases. The control system also had to ensure that the monitoring values of the wastewater treatment plant effluent were always reliably maintained.
THE SOLUTION
Stadtwerke Trier used Xylem Vue´s Plant Real-Time Decision Support application. This technology is based on artificial neural networks, which are used to create data-driven models for the degradation of carbon, nitrogen and phosphorus compounds. The system receives all the parameters and data required for this in real time from the existing SCADA system at the wastewater treatment plant.
The resulting digital twin allows for hundreds of scenarios to be simulated within seconds, so that the required aeration intensity for the biological degradation of carbon and nitrogen compounds, as well as the chemical requirement for phosphorus precipitation, are optimally controlled, depending on the current and expected load of the wastewater treatment plant.
RESULTS
At the beginning of 2018, the optimisation results of the first phase were compared with the data from previous WWTP operations. This led to the establishment of an important parameter for measuring success: the specific energy used to eliminate one kilogram of chemical oxygen demand (COD). This parameter highlights avoidable fluctuations in plant operations.
A significant reduction in these fluctuations, and thus in situational peak energy consumption, has been achieved thanks to optimised plant operations. Since the implementation of the Plant Real-Time Decision Support application, Trier’s main plant has reduced energy consumption in the aeration system by over 20%. This corresponds to savings of 200,000 kWh/year. All monitoring values of the effluent are also safely and continuously complied with.
