A full-scale operational digital twin for a water resource recovery facility-A case study of Eindhoven Water Resource Recovery Facility

Digital transformation for the water sector has gained momentum in recent years, and many water resource recovery facilities modelers have already started transitioning from developing traditional models to digital twin (DT) applications. DTs simulate the operation of treatment plants in near real time and provide a powerful tool to the operators and process engineers for real-time scenario analysis and calamity mitigation, online process optimization, predictive maintenance, model-based control, and so forth. So far, only a few mature examples of full-scale DT implementations can be found in the literature, which only address some of the key requirements of a DT. This paper presents the development of a full-scale operational DT for the Eindhoven water resource recovery facility in The Netherlands, which includes a fully automated data-pipeline combined with a detailed mechanistic full-plant process model and a user interface co-created with the plant's operators. The automated data preprocessing pipeline provides continuous access to validated data, an influent generator provides dynamic predictions of influent composition data and allows forecasting 48 h into the future, and an advanced compartmental model of the aeration and anoxic bioreactors ensures high predictive power. The DT runs near real-time simulations every 2 h. Visualization and interaction with the DT is facilitated by the cloud-based TwinPlant technology, which was developed in close interaction with the plant's operators. A set of predefined handles are made available, allowing users to simulate hypothetical scenarios such as process and equipment failures and changes in controller settings. The combination of the advanced data pipeline and process model development used in the Eindhoven DT and the active involvement of the operators/process engineers/managers in the development process makes the twin a valuable asset for decision making with long-term reliability. PRACTITIONER POINTS: A full-scale digital twin (DT) has been developed for the Eindhoven WRRF. The Eindhoven DT includes an automated continuous data preprocessing and reconciliation pipeline. A full-plant mechanistic compartmental process model of the plant has been developed based on hydrodynamic studies. The interactive user interface of the Eindhoven DT allows operators to perform what-if scenarios on various operational settings and process inputs. Plant operators were actively involved in the DT development process to make a reliable and relevant tool with the expected added value.

The transition of WRRF models to digital twin applications

Digital Twins (DTs) are on the rise as innovative, powerful technologies to harness the power of digitalisation in the WRRF sector. The lack of consensus and understanding when it comes to the definition, perceived benefits and technological needs of DTs is hampering their widespread development and application. Transitioning from traditional WRRF modelling practice into DT applications raises a number of important questions: When is a model's predictive power acceptable for a DT? Which modelling frameworks are most suited for DT applications? Which data structures are needed to efficiently feed data to a DT? How do we keep the DT up to date and relevant? Who will be the main users of DTs and how to get them involved? How do DTs push the water sector to evolve? This paper provides an overview of the state-of-the-art, challenges, good practices, development needs and transformative capacity of DTs for WRRF applications.

An innovative compact system for advanced treatment of combined sewer overflows (CSOs) discharged into large lakes: Pilot-scale validation

Combined sewer overflows discharging into natural water bodies could potentially contaminate them in terms of conventional wastewater parameters and coliform bacteria. When green water infrastructures are not technically feasible or practically sustainable for stormwater management, innovative compact and effective end-of-pipe systems can be of interest. This study presents long-term and real-environment validated data of a compact and rapid treatment system specifically applicable to CSOs that consists of a dynamic rotating belt filter, adsorption on granular activated carbon and UV disinfection steps. The results of treatment for Lake Garda in Italy, showed great potential for TSS, COD and E. coli removal efficiencies with more than 90%, 69% and 99% respectively. Due to the short contact time of GAC adsorption, nutrients removals were not very high. TN and TP removal of around 41% and 19% were observed respectively that suggests further specific nutrients removal processes are required for achieving higher efficiencies. The treatment system, due to its compactness and rapidness could be a great asset for water utilities in different EU catchments that are dealing with the frequent CSO events. In addition, the possibility of using different combinations of treatment steps allows the choice of different treatment scenarios depending on the treatment goals for any specific catchment.

Optimization of P compounds recovery from aerobic sludge by chemical modeling and response surface methodology combination

Phosphorus recovery has drawn much attention during recent years, due to estimated limited available quantities, and to the harmful environmental impact that it may have when freely released into aquatic environments. Struvite precipitation from wastewater or biological sludge is among the preferred approaches applied for phosphorus recovery, as it results in the availability of valuable fertilizer materials. This process is mostly affected by pH and presence of competitive ions in solution. Modeling and optimization of the precipitation process may help understanding the optimal conditions under which the most efficient recovery could be achieved. In this study, a combination of chemical equilibrium modeling and response surface methodology (RSM) was applied to this aim to aerobic sludge from a plant in Italy. The results identify optimum chemical parameters values for best phosphorus precipitation recovery and removal efficiencies, respectively. Identification of optimal conditions for process control is of great importance for implementing pilot scale struvite precipitation and achieve efficient phosphorus recovery.

Bleeding gastric varices and gastric torsion secondary to a wandering spleen

We are reporting a patient who presente with upper gastrointestinal bleeding which was in part caused by a wandering spleen. Endoscopy revealed erosions of gastric varices in the presence of gastric torsion. At surgical exploration the spleen was present in the pelvis. The twisted and elongated splenic pedicle resulted in a markedly dilated venous system of the proximal stomach and the engorged spleen. The literature of the wandering spleen is reviewed.