Ingmar Nopens

Ghent University | UGhent · Department of Data Analysis and Mathematical Modelling

Twin-screw wet granulation (TSWG) stands out as a promising continuous alternative to conventional batch fluid bed- and high shear wet granulation techniques. Despite its potential, the impact of raw material properties on TSWG processability remains inadequately explored. Furthermore, the absence of supportive models for TSWG process development w...

Organic Solvent Nanofiltration (OSN) is widely recognized as an interesting substitute to the thermal-based separation processes traditionally used in many industries. However, its industrial implementation has been hampered by the relatively poor understanding of the complex phenomena that drive its performance. Consequently, various model formula...

Hydrodynamic stress is an influential physical parameter for various bioprocesses, affecting the performance and viability of the living organisms. However, different approaches are in use in various computational and experimental studies to calculate this parameter (including its normal and shear subcomponents) from velocity fields without a conse...

In recent years, continuous twin-screw wet granulation (TSWG) is gaining increasing interest from the pharmaceutical industry. Despite the many publications on TSWG, only a limited number of studies focused on granule porosity, which was found to be an important granule property affecting the final tablet quality attributes, e.g. dissolution. In cu...

In the pharmaceutical industry, twin-screw wet granulation has become a realistic option for the continuous manufacturing of solid drug products. Toward the efficient design, population balance models (PBMs) have been recognized as a tool to compute granule size distribution and understand physical phenomena. However, the missing link between mater...

In the last decade, twin-screw wet granulation became an essential technology for continuous pharmaceutical tablet production. Consequently, interest in (semi-)continuous fluidized bed drying systems as a subsequent processing unit has grown. In parallel, it has become pivotal to fully understand and control manufacturing processes in line with in...

Population balance models (PBM) have been widely used to model the twin-screw wet granulation (TSWG) in the continuous manufacturing of solid dosage forms. However, some knowledge gaps, such as material properties and process parameters, remain, which hampers the applicability of new drug developments. This work presents a hybrid model of a compart...

Hydrodynamics can play an important role in drinking water treatment plants in the operation and efficiency of the treatment processes that take place in a dissolved air flotation process (DAF). For the DAF, it is important to reduce flock concentration and for the clean water, ‘dead’ zones with long residence times must be avoided to prevent biolo...

Population balance models (PBMs) have been widely studied for the simulation of continuous twin-screw wet granulation. Due to the limited data availability and computational efforts, one-dimensional PBM is the most popular application to the pharmaceutical industry. While multi-dimensional PBMs can predict multiple granule quality attributes, model...

In its fresh state, cement - the hydraulic binder responsible for the hardening of concrete - is a highly concentrated suspension in which nano and mesoscopic phenomena and their interactions determine its macroscopic rheological behaviour. This complexity creates significant challenges in the modelling of the material. In this work, a multiscale m...

One of the bottlenecks of mechanistic plant-wide water resource recovery facility (WRRF) models commonly used in most of the available digital twin (DT) cases relates to the level of hydrodynamics details included in these models. They often neglect detailed hydrodynamics of the reactors and simplify the mixing behaviour by the Tanks-In-Series (TIS...

The importance of residence time distribution modeling is acknowledged as a tool for enabling material tracking and control within a continuous manufacturing line in order to safeguard both product quality and production efficiency. One of the first unit-operations into a continuous direct compression line (i.e. CDC-line) worthwhile doing extensive...

Professor Gustaf Olsson has devoted countless hours over many years to Water Science and Technology, Water Supply and Water Practice and Technology as an author, reviewer, editor and Editor in Chief until finally stepping down from all functions in 2021. In order to honour Prof. Olsson's devotion and contribution to the journals, IWA Publishing has...

Residence time distributions (RTDs) are a valuable tool for product tracking in the unit operations of a line for the continuous manufacturing of pharmaceutical oral solid dosage (OSD) and the integrated system itself. The first unit operation in such a continuous line in which extended intermixing can occur, is typically a feeder. The RTD of a fee...

Ceramic membranes are highly promising for application in organic solvent nanofiltration (OSN). Unfortunately, the governing molecular transport mechanisms are not yet fully understood. To study the importance of different transport mechanisms, we analyze transport through these membranes using Maxwell-Stefan theory. We show that the total flux is...

Cooling towers are a primary and vital component of the cooling cycle in a chemical plant. The heat and mass transfer inside a cooling tower is governed by the complex geometry of the fill, flow conditions and turbulence degree of the air and liquid phases. These aspects of a cooling tower are generally modelled using computational fluid dynamics,...

In this paper, the well-known Benchmark Simulation Model No. 1 (BSM1) was modified with a new model for the secondary clarifier to improve its prediction capability. The Bürger-Diehl settler model was integrated with the activated sludge models to represent a complete model of an activated sludge train. Based on this integrated model, twin-level co...

Acidogenesis of sugarcane vinasse at 15 and 20 kgCOD m⁻³ in a batch bioreactor occurred via acrylate and homoacetogenesis pathways. Both these pathways were incorporated into the Anaerobic Digestion Model Number 1 (ADM1) and they were validated with biomolecular analysis. As a novelty of this work, ADM1 was modified integrating a new lactate consump...

This Scientific and Technical Report (STR) provides in-depth fundamentals and guidelines regarding Computational Fluid Dynamics (CFD) simulations of Water Resources Recovery Facilities (WRRFs) unit processes (e.g. headworks, aerobic and anaerobic biological reactors, settling tanks, disinfection). Each unit process is described with respect to: Lit...

This Scientific and Technical Report (STR) provides in-depth fundamentals and guidelines regarding Computational Fluid Dynamics (CFD) simulations of Water Resources Recovery Facilities (WRRFs) unit processes (e.g. headworks, aerobic and anaerobic biological reactors, settling tanks, disinfection). Each unit process is described with respect to a...

The pharmaceutical industry has been quite successful in developing new hydrogenation processes, and the chemistry of hydrogenation is currently well understood. However, it is a complex process to scale and optimize due to its high exothermicity, use of expensive catalysts and solvents, and its mass transfer requirements. Therefore, the aim of thi...

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...

Deep bed filtration, in rapid sand filters, is an important technology used to remove suspended solids when producing drinking water and treating domestic and industrial wastewater. One of the challenges of rapid sand filtration is to reliably predict solids concentration and pressure drop as a function of filtration time. Computational Fluid Dynam...

With increased commitment from the international community to reduce greenhouse gas (GHG) emissions from all sectors in accordance with the Paris Agreement, the water sector has never felt the pressure it is now under to transition to a low-carbon water management model. This requires reducing GHG emissions from grid-energy consumption (Scope 2 emi...

The rising quantity and quality demands in biopharmaceutical manufacturing require a deep understanding of the underlying bioprocesses. For this purpose, computational fluid dynamics (CFD) simulations are typically used to predict the hydrodynamics properties of a bioreactor, offering a toolset for process design. However, CFD approaches are comput...

Given that social interactions drive the spread of infectious diseases amongst humans, one anticipates that human mobility in Belgium affected the spread of COVID-19 during both 2020 "waves". Measures against this spread in turn influenced mobility patterns. In this study, we analyse and mutually compare time series of COVID-19-related data and mob...

Mathematical modelling is increasingly used to improve the design, understanding, and operation of water systems. Two modelling paradigms, i.e., mechanistic and data-driven modelling, are dominant in the water sector, both with their advantages and drawbacks. Hybrid modelling aims to combine the strengths of both paradigms. Here, we introduce a nov...

Hydrodynamics can play an important role in drinking water treatment plants in the operation and efficiency of the treatment processes that take place in a dissolved air flotation process (DAF). For the DAF, it is important to reduce flock concentration and for the clean water, 'dead' zones with long residence times must be avoided to prevent biolo...

In the pharmaceutical industry, the flow of fine powders between different manufacturing steps can be challenging due to both the solid and liquid-like behavior of bulk solids. To better understand flow behavior, the use of predictive models, such as the discrete element method (DEM) has increased in recent years. However, a general model for fine...

UASB reactors are a promising option for environmentally friendly wastewater treatment due to their reduced carbon footprint and their capacity to treat a variety of wastewater strengths, among other recognized advantages over alternative wastewater treatment systems. The Influent Distribution System (IDS) is a critical structure for generating gra...

We present a compartmental extended SEIQRD metapopulation model for SARS-CoV-2 spread in Belgium. We demonstrate the robustness of the calibration procedure by calibrating the model using incrementally larger datasets and dissect the model results by computing the effective reproduction number at home, in workplaces, in schools, and during leisure...

When electrodialysis (ED) is applied to process streams that are known to foul and scale the system, it can be operated with an oscillating electric field. This procedure is known as pulsed electric fields (PEF) and has been proven to reduce the fouling susceptibility of the system. In literature, the suppression of fouling is attributed to a combi...

Surrounded by intense anthropogenic activities, urban polluted rivers have increasingly been reported as a significant source of greenhouse gases (GHGs). However, unlike pollution and climate change, no integrated urban water models have investigated the GHG production in urban rivers due to system complexity. In this study, we proposed a novel int...

Objectives The coronavirus disease 2019 pandemic has had a major impact on our society, with drastic policy restrictions being implemented to contain the spread of the severe acute respiratory syndrome coronavirus 2. This study aimed to provide an overview of the available evidence on the cost-effectiveness of various coronavirus disease 2019 polic...

Toward further implementation of continuous tablet manufacturing, one key issue is the time needed for start-up operation because it could lead to lower product yield and reduced economic performance. The behavior of the start-up operation is not well understood; moreover, the definition of the start-up time is still unclear. This work investigates...

Residence time distribution (RTD) curves play an essential role in the hydraulic characterization of reactors. Current approaches for obtaining RTD curves in laboratory-scale reactors are time-consuming and subject to large errors. Thus, automated systems to obtain RTD curves in laboratory-scale reactors are of great interest for reducing experimen...

Experimental characterization of solid-liquid mixing for a high shear wet granulation process in a twin-screw granulator (TSG) is very challenging. This is due to the opacity of the multiphase system and high-speed processing. In this study, discrete element method (DEM) based simulations are performed for a short quasi-two-dimensional simulation d...

When trying to reduce the paste content in concrete mixtures for economic reasons, the impact of poor rheology control becomes more prominent. One underlying cause is the incomplete knowledge about force interactions between cement particles originating at the molecular scale. The molecular dynamics simulations presented in this work are conducted...

The number of studies dealing with tertiary ozonation to remove trace organic contaminants (TrOCs) in effluents originating from wastewater treatment plants (WWTPs) is increasing due to the need for upgrading the WWTPs overall performance. To follow-up TrOCs removal in real-time during ozone-based treatment, online surrogate measurements are necess...

In recent years, the interest in continuous manufacturing techniques, such as twin-screw wet granulation, has increased. However, the understanding of the influence of the combination of raw material properties and process settings upon the granule quality attributes is still limited. In this study, a T-shaped partial least squares (TPLS) model was...

Recently, the pharmaceutical industry has undergone changes in the production of solid oral dosages from traditional inefficient and expensive batch production to continuous manufacturing. The latest advancements include increased use of continuous twin-screw wet granulation and application of advanced modeling tools such as Population Balance Mode...

With the increasing digitalisation of the water industry, there is a clear need for improved process models. Here we show a new hybrid methodology combining physical process knowledge and machine learning techniques into the framework of neural differential equations. These equations leverage the interpretability and generalization potential of mec...

Although dissolved air flotation (DAF) plays a crucial role in wastewater treatment, fluid dynamics in the contact zone (CZ) of a DAF tank are still considered black-box processes, which hampers DAF's optimal design and operation. In this article, we perform a modeling study to further unravel the governing mechanisms occurring in a DAF tank. A com...

This report describes the combined impact of different social distancing scenarios, the 501Y.V1 variant and the ongoing vaccination campaign in Belgium and illustrates the importance of epidemic control in the period up to August 1, 2021. • Changing social distancing behaviour as a result of lifting measures too soon might, in spite of the ongoing...

First-principles modeling of dynamical systems is a cornerstone of science and engineering and has enabled rapid development and improvement of key technologies such as chemical reactors, electrical circuits, and communication networks. In various disciplines, scientists structure the available domain knowledge into a system of differential equatio...

Population Balance Modeling (PBM) is a powerful modeling framework that allows the prediction of the dynamics of distributed properties of a population of individuals at the mesoscale [...]

In pharmaceutical wet granulation, drying is a critical step in terms of energy and material consumption, whereas granule moisture content and size are important process outcomes that determine tabletting performance. The drying process is, however, very complex due to the multitude of interacting mechanisms on different scales. Building robust phy...

Supplementary information to: W. Quaghebeur, I. Nopens and B. De Baets, "Incorporating Unmodeled Dynamics Into First-Principles Models Through Machine Learning," in IEEE Access, vol. 9, pp. 22014-22022, 2021, doi: 10.1109/ACCESS.2021.3055353. Abstract: First-principles modeling of dynamical systems is a cornerstone of science and engineering and ha...

Good predictive models are essential in modern chemical industry for control and optimization. Mechanistic models, incorporating physical and empirical knowledge, are dominant. However, the incorporated knowledge is inherently a simplification of reality, resulting in model structure uncertainty. Moreover, gathering the necessary knowledge is time-...

Fouling of the ion-exchange membranes by colloidal substances present in bio-based process streams is an important hurdle for electrodialysis. The development of a model is challenged by the limited availability of experimental data and the complexity of the underlying physics. This research addresses this challenge by combining a mechanistic descr...

The detailed structures and distribution of enzymatically active magnetic-responsive dynamic layers (EnzSP) were investigated for the first time in a crossflow superparamagnetic biocatalytic membrane reactor (XF-BMRSP). The trade-off between a higher mass transfer rate, lower fouling tendency, and preventing washout of the dynamic layer, highly dep...

Mathematical models can be a powerful tool in the operation of reverse osmosis (RO) facilities which is often challenged by a varying feed water quality. Most models, however, do not consider both full-scale and good modelling practice, which makes them less suited in practice. In this paper, a generic steady state model for RO was set-up and appli...

Research shows that anaerobic digestion could acclimate to ammonia stress; however, the acclimation remained unaddressed. In this study, evolution of microbial community, functional gene, and pathway was linked with apparent kinetic and performance in unacclimated inoculum under ammonia stress, to deepen understanding of the acclimation. The second...

Migrating fish species are worldwide in decline due to several global changes and threats. Among these causes are man‐made structures blocking their freshwater migration routes. Shipping canals with navigation locks play a dual role in this. These canals can serve as an important migration route, offering a short cut between freshwater and the sea....

As a response to a rapidly rising number of SARS-CoV-2 infections, the Belgian government imposed strict social contact restrictions on March 13th, 2020. After nearly two months, the curve was succesfully flattened and social restrictions were gradually released. Unfortunately, pharmaceutical interventions are not yet available so it is expected th...

Background Acoustic positioning telemetry allows to collect large amounts of data on the movement of aquatic animals by use of autonomous receiver stations. Essential in this process is the conversion from raw signal detections to reliable positions. A new advancement in the domain is Yet Another Positioning Solver (YAPS), which combines the detect...

Understanding mixing behavior and its impact on conversion processes is essential for the operational stability and conversion efficiency of anaerobic digestion (AD). Mathematical modelling is a powerful tool to achieve this. Direct linkage of Computational Fluid Dynamics (CFD) and the kinetic model is, however, computationally expensive, given the...

Background Acoustic positioning telemetry is nowadays widely used in behavioural ecology of aquatic animals. Data on the animal’s geographical location and its changes through time are used to study for instance movement patterns, habitat use and migration. The acoustic signals are detected by stand-alone receivers, allowing to collect huge amounts...

This data paper aims to provide data on the effect of the process settings on the fouling of an electrodialysis pilot installation treating a sodium chloride solution (0.1 M and 0.2 M) in the presence of humic acid (1 g/L). This data was used by “Colloidal fouling in electrodialysis: a neural differential equations model” [1] to construct a predict...

Emission of N2O represents an increasing concern in wastewater treatment, in particular for its large contribution to the plant's carbon footprint (CFP). In view of the potential introduction of more stringent regulations regarding wastewater treatment plants' CFP, there is a growing need for advanced monitoring with online implementation of mitiga...

Ambitious energy targets in the 2020 European climate and energy package have encouraged many stakeholders to explore and implement measures improving the energy efficiency of water and wastewater treatment facilities. Model-based process optimization can improve the energy efficiency of wastewater treatment plants (WWTP) with modest investment and...

Wetting is the initial stage of wet granulation processes during which the first contact between the powder and the liquid occurs. Wetting is a critical step to allow granule growth and consolidation, but also to ensure uniform active pharmaceutical ingredient (API) distribution over all granule size fractions. A physical understanding of the wetti...

The attachment of colloids to the ion-exchange membranes in electrodialysis is an important hurdle when processing bio-based process streams. Previous research showed that fouling strongly depends on the crossflow velocity, the current and the salt concentration of the medium. Predicting the influence of these variables on the fouling rate is chall...

A literature screening on computational fluid dynamics (CFD) modelling in water treatment applications showed a vast range of validation ranging from no validation at all, over RTD and tracer testing, to velocity field, species concentration and, finally turbulence properties measurements. The validation level also differs depending on process scal...

Understand how the long-term government response to the Covid-19 outbreak can be optimised using mathematical methods commonly used in chemical engineering. Using a discrete model predictive controller (MPC), it is possible to come up with an optimal government response to the covid-19 outbreak that does not overload the number ICU beds in Belgium...

In the pharmaceutical industry, the transition to continuous manufacturing of solid dosage forms is adopted by more and more companies. For these continuous processes, high-quality process models are needed. In pharmaceutical wet granulation, a unit operation in the ConsiGma TM-25 continuous powder-to-tablet system (GEA Pharma systems, Collette, Wo...