Category

Press Release

Read editorial articles and press releases from INVENT Umwelt- und Verfahrenstechnik AG here.

Wastewater Treatment for Leather Industry

By Press Release
  • Arzignano_Foto 9_610x440
  • Arzignano_Foto 10_610x440

Efficient wastewater treatment under extreme conditions – INVENT increases the performance of the wwtp Arzignano

In Italy’s Chiampo Valley, industrial wastewater from the leather industry poses particular challenges for water treatment. With INVENT HYPERCLASSIC®-Mixing and Aeration Systems, plant operator Acque del Chiampo is boosting the performance of its biological treatment stage – thereby improving the efficiency of the entire plant. 

With its powerful technology, the Arzignano wastewater treatment plant can cope with exceptional loads. This is because the region is one of the largest centers for leather production in Europe and one of the most important industrial areas in Italy. Around 30% of European leather is processed here, and around 1% of Italy’s economic output is generated here.

A strong industrial location places special demands on wastewater treatment:

  • Up to 30,000 m³ of wastewater is fed into the plant every day via an industrial wastewater system around 40 km long.
  • Wastewater from the leather industry is particularly complex and requires the removal of high BOD and COD levels, significant nitrogen and ammonia concentrations, as well as surfactants, sulfites, chlorides, PFAS residues and chromium.
  • The treatment process must reliably manage significant process-related fluctuations in wastewater volumes.
  • In addition to industrial wastewater, the plant treats up to 15,000 m³ of domestic wastewater every day, corresponding to a total capacity of approximately 1.63 million population equivalents (PE).
Comprehensive modernization: 8 HYPERCLASSIC®-Mixing and Aeration Systems combine high performance with environmental protection

The wastewater treatment plant in Arzignano was designed back in 1976 to meet the enormous demands of the industrial region and has been continuously developed ever since. Now, the plant is undergoing comprehensive modernization, with Acque del Chiampo aiming to set new technological standards in environmental and health protection.

The upgrade is being carried out during ongoing operations. First, a new bypass tank was built, in which the eight HYPERCLASSIC®-Mixing and Aeration Systems are used. Four additional tanks are now being retrofitted without interrupting operations. Once this conversion is complete, 28 HYPERCLASSIC®-Mixing and Aeration Systems will ensure powerful and efficient mixing and aeration of the biological process.

The HYPERCLASSIC®-Mixing and Aeration Systems – a perfect match

To meet the demanding requirements of biological treatment, Acque del Chiampo was looking for a system that could treat large volumes of highly contaminated wastewater in an energy-efficient manner, withstand the demanding wastewater properties of tanneries over a long period of time, and be robust against load fluctuations.

The HYPERCLASSIC®-Mixing and Aeration System meets these requirements:

  • A high oxygen input combined with stable mixing keeps even heavy tannery pollutants suspended. This prevents them from sinking to the bottom of the tank, which improves process quality and keeps the tanks clean and virtually free of deposits.
  • The oxygen gradients generated in different areas of the tanks enable optimized process control, which ensures a trouble-free biological degradation process even with fluctuating water volumes.
  • The homogeneous oxygen distribution ensures maximum efficiency in aerobic degradation. This leads to significant energy savings throughout the entire process.
  • A practical frame construction improves accessibility, making maintenance tasks easier to perform.
SOTE and MIX tests confirmed the performance of the HYPERCLASSIC®-Mixing and Aeration Systems

With 97.1% COD degradation, 99.1% solids removal, and 91.9% nitrogen reduction, the plant demonstrates above-average cleaning performance. It illustrates how the renewed biological stage – driven by INVENT‘s mixing and aeration technology – increases the performance level of the entire plant and process stability.

The cooperation with Acque del Chiampo thus impressively illustrates how intelligent, resource-saving wastewater treatment can also be successful in the demanding leather industry.

Find out more about our innovative products!

In our video we introduce the INVENT mixing technology

Video HYPERCLASSIC Rühr- und Begasungssystem Palm Papier Aalen Montage

HYPERCLASSIC®-Mixing and Aeration System

The HYPERCLASSIC®-Mixing and Aeration System was developed and optimized especially for the tough application in industrial and municipal wastewater treatment plants.

February 26, 2026
Love0

Retrofit for denitrification tanks

By Press Release
  • 2_KA Hagen INVENT Donutbecken_610x440
  • 1_KA Hagen INVENT_610x440
  • 3_KA Hagen INVENT HYPERCLASSIC Rührwerk_610x440

Cost-effective retrofit for denitrification tanks during ongoing operation at the wwtp Hagen-Boele

Following the insolvency of Kabel Premium Pulp & Paper GmbH, the Ruhrverband took over the paper mill’s wastewater treatment plant at Hagen-Boele, Germany. The plant was originally designed for wastewater from the paper industry and municipal wastewater and had to be converted at short notice to operate exclusively with municipal wastewater. This created the need to set up unventilated zones for denitrification in existing aeration tanks without interrupting plant operation for long periods or carrying out extensive structural modifications.

The plant has two large donut-shaped tanks, the outer ring of which is divided into several segments. For the new process control, some of these segments were to be operated as denitrification zones. The boundary conditions were challenging. Due to existing scraper bridges, only very limited installation space was available above the water level. There was considerable time pressure for implementation. Complete emptying of the tanks was out of the question for operational and economic reasons.

INVENT developed a suitable solution concept, which centered on the use of HYPERCLASSIC®-Mixers in combination with steel bridges adapted to the specific plant. The vertical design of the mixers and the compact drive design allowed them to be installed under the existing scraper bridges without impairing their function. At the same time, the mixers could be aligned in such a way that accessibility and operational safety were guaranteed under the cramped space conditions.

The steel bridges were the second central element of the concept. They were designed to rest on existing structural elements and could be installed without extensive modifications to the con , concrete, or basin walls. This eliminated the need for costly preparatory work and significantly reduced installation time at the plant. In addition, open side brackets were provided to accommodate the mixers. In combination with the HYPERCLASSIC®-Mixers, this bridge concept enabled complete installation in the filled basin. The load was transferred and assembly carried out via existing structures, incorporating the existing scraper bridge. For the operator, this meant rapid implementation with manageable project costs.

With their characteristic geometry, the HYPERCLASSIC®-Mixers ensure uniform flow distribution and reliable suspension of the activated sludge at a comparatively low power density. Especially in denitrification zones, stable mixing without air ingress is crucial for process reliability.

The INVENT solution at a glance:

  • Fast and cost-efficient retrofit, without new construction and without downtime of the basins
  • Installation in filled basins, made possible by steel bridges and vertical hyperboloid mixers
  • High energy efficiency with reliable denitrification, low power density with high circulation capacity
  • Optimized for donut tanks and confined installation situations, even under existing scraper bridges
  • Operator-friendly and future-proof, suitable for municipal requirements and stricter discharge values from 2026

The Hagen-Boele project exemplifies that stable denitrification will remain a central element of municipal wastewater treatment in 2026, especially when taking over and converting existing plants. At the same time, it illustrates how intelligent concepts can be used to continue using existing tanks in the short term and adapt them to new operational requirements without new construction or lengthy downtimes.

Further information about our innovative mixing technologies!

In our video we introduce the INVENT mixing technology

INVENT Video Rühren und Mischen Hyperclassic Rührwerk

HYPERCLASSIC®-Mixer evolution 7

With the current version of the HYPERCLASSIC®-Mixer evolution 7, the seventh, completely revised and revolutionary improved version of the classic hyperboloid agitator is now available.

February 5, 2026
Love0

INVENT technology is powering Schwalbachtal

By Press Release
  • Beckenübersicht_610x440
  • IMG_3465_610x440
  • IMG_3476_610x440

INVENT technology has been powering the Schwalbachtal wastewater treatment plant since 1997

The municipal wastewater treatment plant in Schwalbachtal, Bavaria, was upgraded in the mid-1990s to improve the efficiency and reliability of the biological treatment stage. As part of this modernization, the Utility selected INVENT technologies in 1997: a first-generation HYPERCLASSIC®-Mixer for continuous, homogeneous basin mixing and an E-FLEX®-Aeration System for fine-bubble oxygen transfer.

The treatment facility consists two aeration basins, each 14.5 m in diameter with a total volume of approximately 1,350 m³. Both tanks operate as Sequencing Batch Reactors (SBR) and treat roughly 2,000 m³ of wastewater per day across three shifts.

The original FRP components of the mixers installed in 1997 remain in service today. Only the gear motors have been replaced during normal lifecycle maintenance. The shaft and mixer body made of fiber-reinforced high-performance polymer (FRP) provide long-term corrosion resistance and eliminates material fatigue even under continues intermittent SBR operation.

Each basin is equipped with five E-FLEX®-aeration modules for efficient fine-bubble oxygenation. Their stainless steel frames have operated unchanged since commissioning. The flexible membrane hoses move during aeration, preventing fouling and deposit formation. This maintains low headloss, stable oxygen transfer and reduced blower energy demand over time.

Since start-up in 1997, only two membrane replacements (2008 and 2024) and two motor replacements were required. The original FRP mixer shaft and hyperboloid mixer body remain fully intact and in service, without any signs of corrosion or material fatigue. Because the plant operates two biological tanks, all maintenance work could be carried out on one basin while the other remained fully operational, so overall plant operation was never interrupted.

The combination of hyperboloid mixing and fine-bubble aeration ensures rapid and uniform oxygen distribution. This supports stable biological performance, promotes compact activated sludge flocs and enables efficient nitrification and denitrification. During anaerobic phases, the characteristic hyperboloid flow pattern ensures efficient redistribution, contributing to robust SBR process stability.

The plant’s three decades of continuous operation without corrosion or material fatigue highlight the long-term reliability of the INVENT equipment installed. This durability minimized downtime and maintenance interventions, providing stable process performance for the operator. Today’s INVENT HYPERCLASSIC®-Mixer Evolution7 and the iGSR®-System for intermittently operated and granular sludge reactors build directly on this legacy. They follow the same high-quality production standards and retain the flow characteristics, material durability and energy efficiency of the technology that has been operating successfully in Schwalbachtal since 1997.

Further information about INVENT Technologies!
December 9, 2025
Love0

CFD Solutions for CYBERFLOW

By Press Release

Groundbreaking CFD solutions for wastewater treatment: The CYBERFLOW®-Accelerator

INVENT Umwelt- und Verfahrenstechnik AG, a company with deep roots in fluid mechanics at the University of Erlangen-Nuremberg, has been a pioneer in CFD simulations for wastewater applications since its creation. Recognizing their potential, INVENT established THINK Fluid Dynamix®, a specialized business unit offering advanced CFD-based engineering solutions for the water, wastewater, and chemical industries.

The challenge of wastewater modeling

Modeling hydraulic processes in wastewater treatment requires more than just technical expertise—it calls for a multidisciplinary team with practical, on-the-ground experience. Achieving optimal results involves not only simulating fluid behavior but also understanding the intricate interactions between chemistry, biology, solids handling, civil engineering, material selection, equipment integration, and cost-efficiency.

With over 30 years of experience and a technical unit combining broad technical knowledge and deep industry insight, THINK Fluid Dynamix® delivers dependable and innovative solutions tailored to real-world challenges.

CFD simulations bring a wide range of advantages to wastewater treatment, including enhanced process efficiency, reduced operational costs, and greater environmental sustainability. These digital tools are applied to a variety of systems and processes — from inflow screening and analyzing flow distribution in channels and pipelines, to optimizing mixing and aeration in tanks, assessing the behavior of oxidation ditches, clarifiers, anaerobic digesters, and more. Additionally, these simulations are used in product development, such as the CYBERFLOW®-Accelerator, allowing for the design and validation of innovative treatment components and equipment before physical prototypes are built.

Figure 1: CFD simulation of the CYBREFLOW®-Accelerator

The CYBERFLOW®-Accelerator

To make the INVENT CYBERFLOW®-Accelerator a revolutionary flow generator it introduces innovative design principles.

This is made possible by a holistic, fluid mechanical optimization approach, which considers not only on the propeller design, but the interaction of the flow with the entire machine.

This approach focuses on optimizing all aspects for the design and application including:

  • Turned flow direction for vortex free flow pattern:
    Conventional flow generators suffer from turbulent inflow hitting the propeller, causing major efficiency losses. The CYBERFLOW®-Accelerator eliminates this issue by ensuring a completely undisturbed upstream flow, enabling higher flow rates with less energy input.
  • “Anti-vortex” fin:
    Standard propellers generate inefficient radial and tangential flows that create vortices and waste energy. The CYBERFLOW®-Accelerator uses an anti-vortex fin to eliminate these losses and recover energy by converting unwanted flow components into useful axial flow.
  • INVENT Power Trim Technology®:
    Instead of aligning the shaft horizontally like traditional systems, the CYBERFLOW®-Accelerator angles it slightly upward. This reduces friction at the tank bottom and improves efficiency
  • Fluid mechanically optimized base frame:
    The optimized base frame avoids bulky rectangular tubes and instead uses cast metal structures with minimal surface and drag. This fluid-optimized design minimizes resistance and maximizes flow efficiency.
Conclusion

The CYBERFLOW®-Accelerator show cases the possibilities behind computational fluid dynamics (CFD) in wastewater treatment. Engineered through advanced CFD simulations and a holistic design philosophy, each design element is purpose-built to enhance performance, reduce operational costs, and support sustainable treatment processes. As a result, the CYBERFLOW®-Accelerator is more than just a product; it is a demonstration of how THINK Fluid Dynamix® transforms deep scientific understanding into powerful, real-world engineering solutions for the future of water and wastewater treatment.

Figure 2: CYBREFLOW®-Accelerator

Author: Lea Diehl

Download the brochure here!
November 10, 2025
Love0

Optimizing MBBRs with CFD

By Press Release, Project Report, Think Fluid Dynamix

Figure 1: Flow velocities experienced by the carriers in the IFAS reactor

Optimizing MBBRs with advanced CFD for Blue Plains Advanced WWTP

Wastewater treatment is a critical concern for industries and municipalities worldwide, and process optimization and energy savings are more important than ever. Among the array of treatment technologies for biological wastewater treatment, the Moving Bed Biofilm Reactor (MBBR) stands out as an efficient, compact, and low-maintenance solution. This article explores the critical role of Computational Fluid Dynamics (CFD) in optimizing MBBR design and performance.

MBBR Technology: A brief overview

MBBRs use vast numbers of small, floating polyethylene carriers, each offering a large surface area for bacterial growth. MBBRs offer several advantages, including compactness, operational flexibility, and robustness in handling high organic loads. These reactors rely on the interaction between wastewater, biofilm-covered carriers, and a controlled environment (often involving aeration). Energy efficient treatment depends on maximizing the contact between these elements. Key design factors, influencing this interaction, include:

  • Reactor Geometry: Tank size, shape, and configuration directly impact fluid mixing and carrier dispersion. Poor design can lead to dead zones and reduced treatment efficiency.
  • Carrier Fill Ratio: Balancing sufficient biofilm surface area with adequate carrier movement is crucial. Overfilling can hinder circulation and promote clogging.
  • Aeration System Design: Uniform oxygen distribution is essential for microbial activity. The aeration system also plays a role in carrier mixing.
  • Flow Distribution: Even flow distribution prevents stagnation and short-circuiting, ensuring consistent contact between wastewater and biofilm.
CFD and the challenge of simulating MBBRs

CFD is a field of engineering that uses numerical analysis and data structures to simulate and predict fluid flow, heat transfer, and related phenomena by discretizing the governing equations of fluid mechanics (such as the Navier-Stokes equations). In the wastewater treatment industry, CFD helps to simulate, evaluate and optimize processes such as mixing, aeration, chemical dosing, hydraulic distributions, etc. From activated sludge tanks to more advanced systems like Moving Bed Biofilm Reactors (MBBRs), CFD insights lead to improved operational efficiency, lower costs, and more reliable compliance with environmental regulations.

CFD modeling of MBBRs has enormous advantages, but is far from simple. MBBR systems can contain hundreds of millions of carriers. Simulating the drag force, collision dynamics, individual trajectories of each carrier, a two-way coupling (fluid-carrier interaction) quickly escalates into a highly complex problem from computational perspective. The true challenge lies in modeling each individual carrier, as they come in a variety of shapes, sizes and densities.

Replicating the detailed internal structures of each carrier in CFD is computationally prohibitive. As a result, simplified representations of the original problem become necessary. These simplifications introduce a number of modeling uncertainties and, therefore, no matter how sophisticated the CFD code, empirical data remains essential for grounding simulations in reality.

Advanced CFD modeling: a DEM and calibration with experimental data

THINK Fluid Dynamix® now developed a solution to these challenges: a numerical model that couples the Discrete Element Method (DEM) with CFD to simulate both the fluid flow and the carrier particles. The fluid-carrier interaction is calibrated using experimental data from a series of mixing tests for each carrier type.

DEM is a numerical technique primarily used to model the behavior of collections of individual particles in processes where particle-particle and particle-boundary interactions play dominant roles. When DEM is coupled with CFD, it enables simultaneous simulation of the fluid flow around (and through) these particles, as well as the particles’ motion due to fluid forces and inter-particle collisions. This coupling is crucial for accurately predicting the overall behavior of liquid-solid flows.

In practice, DEM often relies on basic geometrical shapes (such as spheres, cubes, or cylinders) to represent carrier particles because replicating detailed internal structures in CFD is computationally impractical. Therefore, the methodology uses these simplified geometries but calibrates parameters – such as collision properties, effective density, and representative size – against physical experiments. Specifically, the behavior of a given carrier type is observed in a reactor over a range of mixing intensities to match simulation outcomes with experimental data.

The calibration procedure proceeds as follows:

  • Measuring Carrier Dynamics: Conduct physical experiments in a mechanically stirred tank reactor to track how carriers behave under known flow conditions (mixing intensities).
  • Adjusting Model Coefficients: Tune friction coefficients, collision parameters, representative density, and size until the simulation results align with the experimental measurements.
  • Scaling Up: Once calibrated, the numerical model can be reliably applied to full-scale reactors.

Figure 2: Test tank at the facility (left) and the CFD simulated tank at initial conditions (right)

Figure 3: Simulation of resuspension test of carrier media at specific operating condition

Case Study: DC Water Project at Blue Plains Advanced WWTP

The Blue Plains Advanced Wastewater Treatment Plant initiated a significant upgrade to convert its existing biological reactors into Integrated Fixed-Film Activated Sludge (IFAS) reactors, a variant of Moving Bed Biofilm Reactor (MBBR) technology. As a key component of this initiative, a full-scale pilot reactor was designed and analyzed using a coupled Computational Fluid Dynamics–Discrete Element Method (CFD-DEM). The primary objective of this pilot study was to thoroughly assess the hydraulic and mixing behavior anticipated from the introduction of IFAS media into an existing anoxic tank. The CFD simulations offered detailed insights into fluid flow and mixing phenomena, while critically incorporating the interactions between the IFAS media and the surrounding fluid environment.

The CFD-DEM analysis facilitated a comprehensive evaluation of mixing quality under various operating conditions. These conditions included different mixer configurations, various types of IFAS media, and multiple hydraulic residence times. The systematic examination of Key Performance Indicators (KPIs) to quantify mixing effectiveness included local flow velocities, the extent of carrier media homogenization throughout the reactor volume, the identification of potential dead or stagnant zones, and the detection of any short-circuiting phenomena.

This methodology played a crucial part in the engineering of the whole project, offering the ability to accurately quantify parameters and visualize intricate flow-media interactions within the reactor that are exceedingly difficult, if not impossible, to capture comprehensively through traditional experimental techniques, especially in full-scale, opaque environments. Moreover, employing numerical simulations for such assessments was considerably more cost-effective and time-efficient than relying on extensive physical pilot testing, allowing for the agile exploration of numerous design configurations and operational scenarios with significantly reduced financial and logistical outlay.

Figure 4: The multiphase CFD model of the IFAS reactor

Figure 5: Averaged streamlines of flow in IFAS reactor

Conclusion

This study represents a significant advancement in the modeling and optimization of Moving Bed Biofilm Reactors. By coupling CFD with the DEM and integrating rigorous experimental calibration, the work from THINK Fluid Dynamix® overcomes longstanding challenges in reliably simulating reactors that incorporate a diverse range of carrier media. Historically, the variability in carrier geometries and material properties has limited the predictive accuracy of purely numerical models. The experimental-numerical approach presented here not only validates the simulation framework but also offers detailed insights into the complex fluid dynamics and mixing phenomena inherent to these systems.

Notably, the disruptive project undertaken for DC Water at the Blue Plains Advanced Wastewater Treatment Plant serves as a compelling demonstration of this novel methodology. For the first time, a full-scale pilot reactor was analyzed using the calibrated CFD-DEM model, enabling precise evaluation of key performance parameters such as flow velocities, carrier dispersion, and the identification of stagnant or dead zones under various operating conditions. This case study underscores the practical utility of the approach and its potential to enhance reactor performance, energy efficiency, and treatment efficacy.

Overall, the integration of numerical techniques with experimental calibration establishes a new benchmark for the predictive modeling of MBBR systems. The breakthrough enhances the reliability of reactor design and optimization while laying the groundwork for future research and technological advances in wastewater treatment.

Authors: Efraim Riess-Gonzales and Averil Fernandez, M.Eng.

Find out more about THINK Fluid Dynamix®!

In this video you will learn about THINK Fluid Dynamix® and its team!

THINK Fluid Dynamix® presentation

Learn more about THINK Fluid Dynamix® and our team.

August 26, 2025
Love0

Modern interpretation of the SBR-Process

By Press Release

iSBR®/iGSR®-Process – INVENT’s modern interpretation of the Sequencing Batch Reactor Process

Since we have started our business activities in the early nineties we have been in love with the so called Sequencing Batch Reactor process (SBR) for the biological treatment of municipal or industrial wastewater. Batch processes have the great advantage that the reactor behavior is defined, the boundary conditions stay constant and unexpected events are unlikely to occur while running the treatment cycle.

The INVENT HYPERCLASSIC®-Mixing and Aeration System from the very beginning has been the core of each SBR plant we designed and built. The System can effectively mix without aeration and at a different time efficiently aerate and mix the biomass. This is why it is the ideal basis for SBR and any cyclic or intermittent process.

Figure 1: Schematic diagram of the HYPERCLASSIC®-Mixing and Aeration System

One of our core competencies has always been to deeply understand and analyze fluid mechanical correlations and to use this understanding to design superior products for the water and wastewater industry.

The focus of our activities is on the essential unit processes

  • Mixing
  • Mass transfer
  • Solid/liquid separation

In these areas good fluid mechanical design can make a real difference and improve overall process efficiency and save energy. This is how whole product families of advanced mixing systems, highly efficient aeration systems, high performance decanters and innovative filters developed over time.

A second of our core competencies is to deeply understand the treatment processes and to know how to integrate our products into our client’s processes most beneficially.

This inevitably led to a deep understanding of the in and outs and specific requirements of SBRs and a dedicated family of products for this special process.

These include:

Each product can be sized and customized for the individual plant and application to perfectly match each client’s needs and specifications.

In cases in which the client wishes to benefit from and make use of our experience and expertise we can offer our design and engineering package along with our hardware package. We can complement this integrated hard- and software package with installation supervision, start-up and training and supply a complete SBR package. We call this in case of a conventional process design iSBR® and in case of a granular sludge process iGSR®. These complete systems can be used in all common wastewater treatment applications such as e.g.

  • Municipal wastewater treatment
  • Industrial wastewater treatment
  • De-ammonification process
  • Granular Sludge processes

The four main areas in which we have achieved improvements compared to conventional systems in the market are

  • the key equipment,
  • the overall reactor design,
  • the overall process design, and
  • the overall fluid mechanical design

Overall reactor design

The iSBR®/iGSR® reactor design is based on the idea of creating several individual zones in one reactor module, which are positioned in series. This design, which only works thanks to the unique features of the HYPERCLASSIC®-Mixing and Aeration System, allows for the realization of an advanced process which has

  1. Cascaded reactor design
  2. Runs continuously
  3. And cyclic

We call this iC³-Process.

Cascaded reactor design

Each HYPERCLASSIC®-Mixing and Aeration System creates an individual zone which are cascaded over the entire reactor. This allows for a much higher process flexibility since we can run different modes and process parameter in the individual zones during the same cycle. The first zones for example can act as a selector while the last zone is decanting.

The individual steps of the iSBR®/iGSR®-Process

We differentiate the five different process phases, which happen at different times and four different spatial zones (Zones 1 – i). These zones are defined by the 4 different spatial zones of equal size in which we can divide each SBR tank.

Overall process design

The continuous inflow and the division of the reactor in individual zones allows for an advanced process design which is explained in this paragraph.

In figure 3 the five basic cycle phases of the iSBR®/iGSR®-Process are shown schematically. After phase 5 the cycle repeats itself and jumps back to phase 1. What happens in the individual phases is as follows.

Figure 2: The five main cycle phases of the iSBR®/iGSR®-Process

1 Fill/Mix (FM)

In this phase the HYPERCLASSIC®-Mixing and Aeration System operates at reduced speed and provides mixing without aeration. Anaerobic conditions due to the continuous filling of wastewater are generated in zones 1 and 2; whereas there are mainly anoxic conditions in zones 3 and 4. In zones 3 and 4 the necessary anaerobic conditions are generated for a partial degradation of organic compounds, which may not be degraded under solely aerobic conditions, and also for biological phosphorus removal.

2 Fill/Mix/Aerate (FMA)

During the aeration cycle filling continues and the HYPERCLASSIC®-Mixing and Aeration System operates at high speed in strong mixing and aeration mode. It efficiently supplies the necessary oxygen for the BOD and COD removal and the nitrification process. Effective mechanical mixing during aeration is very important to maintain and ensure high α-values, to maintain high oxygen transfer rates and to apply the necessary minimum shear stress on the granular biomass.

The HYPERCLASSIC®-Mixing and Aeration System is a proven technology for aeration in bioreactors with granular sludge. Mechanical mixing during aeration is also desirable to avoid foaming and scum on the water surface. The strong mixing furthermore ensures aerobic conditions and a minimized anaerobic core in the sludge flocs.

Due to the high oxygen demand resulting from the feed of fresh wastewater to Zone 1 of the iSBR®, Zone 1 stays during this phase mainly anoxic.

3 Fill/Degas (FDg)

After the aeration cycle has been completed and the blowers have been turned off a short period of strong mixing at increased speed of the HYPERCLASSIC®-Mixing and Aeration System takes place. By this an effective degassing of the sludge flocs is achieved. This improves the sludge settling properties and avoids collection of foam on the water surface.

4 Fill/Settle/Slow Mix 1 (FSPh1)

Due to the anoxic conditions during the settling phase, denitrification processes take place in the first zones of the iSBR® and the HYPERCLASSIC®-Mixing and Aeration System at the inlet of the iSBR®/iGSR® operates at low speed and gently mixes the fresh wastewater with the increasing sludge blanket at the bottom. At this low speed the sludge blanket is maintained at the desired depth. The feed of raw wastewater into the sludge blanket creates, after a short anoxic phase, anaerobic conditions with Bio-P release. Additionally these anaerobic conditions promote the conversion of bCOD1 to rbCOD2 in the inlet zone (Zone 1) of the iSBR®/iGSR® with anaerobic uptake of rbCOD and/or anoxic depletion of the same. This minimizes aerobic uptake of rbCOD, and creates the optimum biochemistry for aerobic granular sludge growth.

5 Fill/Decant/Slow Mix 2 (FDPh2)

During this last step of the iSBR®/iGSR®-Process the wastewater inflow into the sludge blanket and the operation of the HYPERCLASSIC®-Mixing and Aeration System at low speed continues. Anaerobic conditions necessary for Bio-P. are created within the sludge blanket.

In this final phase the iDEC® begins to withdraw the treated effluent (decant) without disturbing the sludge blanket by our waste sludge retrieval system and thus preventing a contamination of the effluent with sludge. During this phase the excess sludge is removed from the settled blanket to maintain the required food to mass ratio for the process design. As soon as the decanting cycle has been completed and the desired discharge volume has been withdrawn from the iSBR®/iGSR®, the decanter raises to its idle position above the water level and the cycle repeats itself.

¹ bCOD: biodegradable chemical oxygen demand

2 rbCOD: readily biodegradable chemical oxygen demand

iSBR®/iGSR® benefits

Continuous flow operation

The INVENT iSBR®/iGSR®-Process uniquely combines the advantages of a batch wise operation with conventional continuous flow across the entire plant. This unique achievement makes large equalization basins in front of the biological reactors unnecessary and further reduces the overall footprint of the plant.

Modular design

Our INVENT iSBR®/iGSR® are based on a modular design. The individual modules consist of either a single or a double train of HYPERCLASSIC®-Mixer/Aerators and 3, 4, 5, 6 or i of them in series. The size of the base modules selected depends on the overall plant capacity which is required, the local conditions and the overall design approach. We prefer plant designs with several individual modules because they offer a higher flexibility and operational safety.

Unique equipment package

INVENT’s unique equipment package used in the iSBR®/iGSR®-Process sets us apart from all other approaches on the market. The flow conditions we can create with the INVENT HYPERCLASSIC®-Mixing and Aeration System are unparalleled and make this process possible. The virtual wall effect ensures the desired reactor behavior. The versatile mixing conditions allow for the safe granular sludge growth. The high aeration performance and quick response times facilitate reliable process control. And if you compare the HYPERCLASSIC®-Mixing and Aeration System with standard membrane aeration systems which are still commonly used, it has a significantly higher performance under process conditions (α- value) and most importantly it does not age and does not loose aeration performance over time.

Our iDEC®-SBR Decanter allows for short decanting times. Our high efficiency iTURBO® High-Speed Blower further reduces the energy consumption and our iFILT®-Diamond Filter can further reduce the amount of suspended solids in the effluent if locally required or if the water shall be re-used e.g. for irrigation purposes. But the star is the team. Having developed all this products in house means that we could optimally design them for the purpose and the use in INVENT iSBR®s and iGSR®s and they optimally work with each other to supply the highest performance in each INVENT project.

Reactor design

Our iSBR®/iGSR®-Design is optimized for this special process and for the equipment used. It allows for maximum mass transfer optimal reactor behavior, small overall footprint and high operational safety and performance. For the reactor design Typical Flow Diagram of an iSBR®/iGSR® plant we use the most modern fluid mechanical simulation tools as well as dynamic simulation for the optimization of the overall process performance and specific load conditions.

Process design

The unique iSBR®/iGSR®-Process allows for aerobic granular sludge production under continuous flow conditions. This is only possible using a cascade of complete mixed stirred tank reactors we create with HYPERCLASSIC®-Mixing and Aeration System and the cyclic process conditions.

Summary

INVENT over the years has been improving the Sequencing Batch Reactor process and is now offering the advanced proprietary iC³-Process in its iSBR®/iGSR® packages to selected clients.

Authors: Dr. Peter Huber, Marcel Huijboom and Dr. Marcus Höfken, INVENT Umwelt- und Verfahrenstechnik AG, Germany

Download the brochure here!
June 4, 2025
Love0

INVENT – 30 Years + Annual Report 2024

By Press Release

_

  • Dr.-Ing. Marcus Höfken
  • Fertigungshalle Fa. INVENT
  • 2025-01_(c)MMerz_001_Gruppenbild ALLE_bearbeitet_610x440
  • INVENT / IFAT 2018
  • IUV_2025_30-Jahre-Video_Homepage News 610 x 440px_lgr_WEB

30 years, one mission: the INVENT success story continues – for clean water worldwide

Innovative strength and the certainty to do the right thing – this is the foundation on which one of the world’s leading water and wastewater treatment companies was able to emerge from a university research project in just three decades. A success that the 150 employees of INVENT Umwelt- und Verfahrenstechnik AG are celebrating together in 2025. However, it will not stop at looking back. INVENT sees its 30-year success story above all as an incentive to courageously push ahead with new projects, even in challenging times – in a commitment to the responsible use of one of the most valuable resources of our time: Water.

When an innovative scientific project was formed at the Chair of Fluid Mechanics at the Friedrich-Alexander University Erlangen-Nuremberg, Germany, in 1995, it not only marked the birth of INVENT, but also the start of ambitious new developments for modern water and wastewater treatment. In 2025 INVENT looks back on the successes achieved with joy and honors them with a summer anniversary celebration to which around 300 employees, companions and partners from three decades of the company are invited.

“With a highly specialized, energy-saving product range and innovative process technology, we have set new standards for the biological wastewater treatment of the future. As a result, we are now one of the top 5 in the industry worldwide – a great success and at the same time a driving force for future innovations,” says Dr. Marcus Höfken, founder and current CEO of INVENT, summarizing the company’s success story.

2024: Solid annual financial statements in challenging times

In the economic turbulence of the recent past, success cannot be taken for granted. INVENT is therefore all the more satisfied at the end of a year in which the German mechanical engineering industry registered a drop in turnover of over 7%. In contrast to the industry trend, INVENT was able to match the previous year’s record pre-tax profit. Incoming orders also remained at a stable high level in 2024 after the record year 2023 (over EUR 40 million).

Commitment to Germany as a business location

In times when there sometimes is too much talk about challenges and too little about opportunities, INVENT remains committed to Germany as a business location. The expansion of the production facility in Erlangen-Dechsendorf continued in 2024. The modern plant now offers optimal conditions for the production of the iFILT®-Diamond Filter, an innovative product in tertiary wastewater treatment that sets new standards with its performance, sophisticated energy and resource efficiency – especially in the fight against microplastics and trace substances.

In addition, construction work began on a new production hall at the headquarters in Erlangen-Eltersdorf in 2025, which will expand production capacity and secure the location in the heart of Central Franconia in the long run.

International location decisions bring resilience in challenging times

INVENT is rooted in Germany and at home in the world. International expansion therefore remains a central component of the corporate strategy.

  • INVENT subsidiaries were founded in Argentina and Uruguay in 2024 to strengthen access to the growth markets in South America.
  • The USA remains a key market for INVENT, which is why the company plans to open its own production site in South Carolina in 2025. It will mark a new chapter in the North American strategy and guarantee optimal options for action locally, even in times of customs disputes.

Dr. Marcus Höfken: “North and South America are becoming increasingly important for us. The current developments confirm our decisions to expand our local sites. They allow us to act faster, more flexibly and with a greater focus on our customers.

A lasting mission: working for clean water worldwide with innovative solutions

In its commitment to global trade, INVENT is committed to a strong drive; it is the same mission that laid the foundation for 30 years of successful innovation: “Our goal remains to be a technological leader – and at the same time to be perceived as a powerful partner in the water industry worldwide. We want to contribute to solving water problems all over the world with high-quality future technologies – and we are ready to be present wherever our solutions are needed,” says Dr. Marcus Höfken.

For INVENT Umwelt- und Verfahrenstechnik AG, there is no doubt that the demand for innovative water and wastewater technology will continue to grow worldwide. The company’s course is therefore set, even in challenging times: INVENT remains focused on growth with a spirit of invention, a sense of responsibility and passion – in Europe, in America, worldwide.

May 30, 2025
Love0

Products for Oil, Gas and Petrochemical Industry

By Press Release
  • wwtp Duslo Sala_HYPERCLASSIC Mixer_Aerator Beitrag Website 587 x 440
  • wwtp Jacksonville Beach_USA Beitrag 587 x 440

Wastewater Treatment for the Oil, Gas and Petrochemical Industry

INVENT develops, produces and distributes innovative mechanical equipment, process technology and plants for the treatment of water and wastewater. The company became well known through the development and market introduction of energy-saving and multitasking hyperboloid mixers as well as mixing and aeration systems for wastewater treatment.

INVENT offers a wide range of efficient stirring and mixing solutions for almost every application in the water, wastewater and processing industry. In the field of aeration technology the scope of products includes a variety of membrane aeration systems for biological wastewater treatment which have been developed and optimized for different applications. These are distinguishable by their functional principle, construction and material, so that an optimal solution can be offered for almost all industrial and municipal requirements. The layout and design of an optimum mixing and/or aeration system is a very complex task. It requires a large amount of competence, know-how and experience. In the case of industrial plants e.g. in the oil, chemical or petrochemical industry, it is most important to understand the production process to a certain degree because this significantly influences the wastewater composition.

An INVENT system solution comprises, depending on the customer’s requirements, the plant design, basic and detailed engineering, project management, delivery of the mechanical components, installation of the plant and the training of plant personnel. The mechanical components, such as mixers, aeration systems, filter, pumps, blowers, fittings and instrumentation, control and automation systems, are carefully selected for an INVENT system solution and coordinated with each other. INVENT takes responsibility for the entire scope of the delivery. This approach reduces the number of interfaces and potential sources of failure.

The recently launched INVENT Granular Sludge Reactor (iGSR®) is the first system that fully exploits the potential of granular activated sludge also for large plants: Reduced process times, higher purification performance with a reduced footprint, low energy consumption and reduced life cycle costs, at the same time delivering high reliability. Its modular concept can be adapted to any plant size. Its design offers a higher level of process stability for hydraulic peaks and load fluctuations than any other system. The iGSR® is already in operation in various plants worldwide, with more facilities currently under construction.

INVENT’s engineering and consulting services range from fluid mechanical optimization of hydraulic structures or processes (Think Fluid Dynamix®) to solving chemical engineering problems, flow simulations using CFD or simulations of entire wastewater treatment plants. These tasks are supported by laboratory research, if necessary.

We offer turnkey solutions for your water project in the oil, gas and petrochemical industry!

Check out our iGSR® video!
February 11, 2025
Love0

Floating solution for pond treatment plants

By Press Release
  • Floating Mixing and Aeration System in Sweden c
  • 3D Rendering
  • Comparison Surface Aeration 3
  • Lessebo
  • Floating HYPERCLASSIC Mixing and Aeration System

Floating HYPERCLASSIC®-Mixing and Aeration System conquers Swedish industrial plants

The innovative Floating HYPERCLASSIC®-Mixing and Aeration System gaining popularity in industrial plants across Sweden, particularly in lagoon wastewater treatment facilities operated by pulp and paper manufacturers. These facilities are specifically designed to address the challenges associated with wastewater treatment and require efficient aeration technologies.

In Sweden, lagoon wastewater treatment plants are widely utilized for treating wastewater from the pulp and paper industry. However, traditional aeration technologies such as surface aerators, membrane aerators, and submerged aerators often encounter issues such as underutilization of volume, poor circulation, and high maintenance requirements. The HYPERCLASSIC®-Mixing and Aeration System is the solution to these challenges by being mounted on a floating platform, enabling aeration close to the bottom and ensuring effective mixing of wastewater through high turbulence.

The adoption of the HYPERCLASSIC®-Mixing and Aeration System has resulted in significant improvements in treatment performance at wastewater treatment plants within the global process industry. Notable enhancements include increased mixed volume, extended mixing range, and improved sludge quality. Additionally, the system’s flexibility and robustness contribute to reduced maintenance costs.

One example involves the replacement of a membrane aeration system in a Swedish industrial wastewater treatment plant with a lagoon capacity of approximately 50,000 m3. By utilizing the HYPERCLASSIC®-Mixing and Aeration System, aeration performance increased by approximately 30% without the need for additional blowers. This led to reduced maintenance costs and overall more efficient wastewater treatment.

In another case, a Swedish industrial wastewater treatment plant replaced three surface aerators with just one HYPERCLASSIC®-Mixing and Aeration System in 2021 This resulted in consistent dissolved oxygen concentrations near the shore. Maintenance requirements decreased significantly, with only an oil change needed every two years. The system’s flexibility allows for adjustments in aeration capacity or switching to agitation mode without aeration to prevent sludge deposits on the lagoon floor.

In the north of Sweden, an industrial wastewater treatment plant retrofitted its lagoon with six mixing and aeration systems and two mixing systems to accommodate higher production volumes. Consequently, some surface and submersible aerators previously in use were decommissioned. The HYPERCLASSIC®-Mixing and Aeration System is mounted on a floating steel platform, with an optional maintenance platform for easy access during oil changes. Connected to a compressed air supply, the system does not require any other fixed or high-maintenance equipment in the tank. Installation on land and subsequent lifting into the lagoon are straightforward. Once secured in place and connected to the process air, the system can be put into operation.

The meticulously planned design facilitates straightforward installation on land and seamless lifting into the lagoon afterward, as illustrated. Lastly, the Floating HYPERCLASSIC®-Mixing and Aeration System is securely positioned as intended, connected to the process air, and put into operation.

INVENT‘s extensive expertise in wastewater treatment is evident in the successful deployment of the Floating HYPERCLASSIC®-Mixing and Aeration System. Engineers in Erlangen consistently develop comprehensive solutions tailored to meet specific needs. The production of these systems primarily utilizes regional materials and services. Since its inception in 2019, the floating mixing and aeration system has proven to be highly effective and is gaining popularity not only in Sweden but also in other regions.

click here for the product video
September 9, 2024
Love0

CFD in the wastewater industry

By Press Release

CFD Simulations in the Wastewater Industry: Bridging Theory and Reality

The realm of fluid mechanics is an intricate web of physics, mathematical models, and real-world applications. In the wastewater industry, understanding these fluid dynamics is not just a scientific exercise but a necessity. Enter Computational Fluid Dynamics (CFD) – a crucial tool that has revolutionized the way we approach and solve real-world fluid mechanics problems.

The origins of INVENT’s CFD journey

In the 1990s, the foundation of INVENT by Dr.-Ing. Marcus Höfken signaled the rigorous application of fluid mechanics in wastewater treatment. Having its roots at the Department of Fluid Mechanics of the University Erlangen-Nürnberg under the leadership of Professor Dr. Franz Durst, INVENT was born out of a genuine passion for fluid mechanics, combined with a rigorous scientific approach.
From its early days, INVENT recognized the potential of CFD simulations, leveraging its capabilities in collaborations with academic institutions. Recognizing its immense potential, the company soon established an in-house CFD department, which quickly evolved to cater exclusively to the intricacies of water and wastewater treatment. From modeling mixers with detailed CAD geometry to multiphase simulations for aerated tanks, INVENT was at the forefront, challenging conventions and elevating standards.

Figure 1: Flow velocity field in SBR

CFD in wastewater treatment: bridging theoretical and practical gaps

But what is CFD? At its core, Computational Fluid Dynamics (CFD) is the use of applied mathematics, physics, and computational software to model and visualize fluid flows. This becomes indispensable in wastewater treatment.

There are many examples: Aerated tanks, for instance, demand multiphase simulations. Such simulations can help predict the Standard Oxygen Transfer Rate (SOTR), a crucial metric in biological wastewater treatment. Additionally, understanding the movement and behavior of suspended solids and activated sludge is vital. CFD helps in modeling these phenomena, providing insights into particle trajectories, settling patterns, and more.

Furthermore, in stirred tank reactors or in pump stations, the effects at the water’s surface, often marked by turbulent behaviors and leading to vortex formation, can be complex. CFD simulations, by modeling these surface effects, assist engineers in designing and optimizing treatment processes.
As we delve further into the realm of wastewater treatment modeling, the emphasis on particular features and techniques becomes indispensable. Here’s why:

  1. Rotating Turbomachinery:
    One cannot underestimate the importance of precisely modeling rotating turbomachinery. In wastewater treatment plants, these machines play pivotal roles, ensuring efficient flow circulation and solids suspension. Accurate modeling ensures reliable representation of real pumping operation
  2. Multiphase Simulation for Aeration:
    Aeration is critical for the biological oxidation processes in the biological treatment of wastewater. Understanding intricate physics, such as bubble dynamics, is essential. Factors like bubble breakup, their eventual coalescence, and mass transfer are key to reliably predict oxygen transfer rate.
  3. Sludge Floc Transport:
    Sludge flocs, or aggregated particles also require further investigation and careful modeling. When considering the multiphase simulations for their transport, a complex factor comes into play: rheology. As the concentration of these flocs increases, the fluid’s behavior deviates from the Newtonian ideal, adopting characteristics of non-Newtonian fluids. This alteration in fluid behavior, coupled with flocculation effects—where particles come together to form larger aggregates—adds layers of complexity to the modeling process.

However, a significant challenge remains. The behavior of biological compounds in wastewater cannot be explicitly modeled within fluid mechanical equations. This is where the role of a numerical-empirical approach becomes essential. By combine theory with empirical data, we ensure accurate results rooted in real-world observations and validations. The potential applications of CFD in this arena are vast, spanning screenings, hydraulic dynamics, water distribution, and beyond. Think of anoxic tanks, clarifiers, oxidation ditches, anaerobic digesters—CFD has them all covered.

Figure 2: Experimental validations in the INVENT laboratories

Tools and collaboration

INVENT is always up to date when it comes to CFD technology. The M-STAR software, with its Lattice-Boltzmann approach for solving Navier-Stokes equations, offers advanced turbulence modeling techniques such as large Eddy Simulation. Powered by GPUs, it permits time-accurate dynamic simulations, providing an unparalleled insight into turbulent phenomena.
Turbulence, after all, is pivotal for mixing. The more accurately turbulence is modeled, the better the predictions related to mixing, a cornerstone in wastewater treatment processes.
Yet, the true strength of INVENT’s CFD department lies not just in its superior software and hardware tools but in its persistent endeavor for numerical validation. By continually comparing simulation results with experimental data, either in collaboration with academic institutions or through onsite experiments at wastewater plants, INVENT ensures the highest fidelity in its CFD simulations.
At the end: the best CFD is much more than a simulation, is also continuous experimental validations and calibration using a numerical-empirical approach.

Figure 3: Tracer test in technical scale tank in the INVENT laboratories

Conclusion

In a world where precision matters, the use of CFD in wastewater treatment is not a luxury but a necessity. As the industry demands more sustainable and efficient solutions, the bridge between theoretical simulations and experimental validations will be even more vital. INVENT will continue to follow this path and simulate the complex waters in the wastewater industry.

Author: Efraim Riess-Gonzales

THINK Fluid Dynamix®
August 27, 2024
Love0