CatMemReac – CO2reduction in the oxidation of micropollutants – energy-intensive vs. novel solar-based processes

הפחתה של פחמן דו חמצני בחמצון של מיקרו מזהמים – תהליכים עתירי אנרגיה למול תהליכים חדשניים מבוססי קרינה סולרית.

Numerous wastewater treatment plants are currently being expanded to include a so-called fourth treatment stage in order to remove trace substances such as hormonally active drugs or pesticides from wastewater. The aim of the German-Israeli water technology cooperation project CatMemReac is to reduce the CO2 footprint in water treatment. This involves replacing energy-intensive processes in the oxidation of micropollutants with new sunlight-based processes.


Green wastewater treatment plants applying photocatalysis for micropollutant removal

Dr. Benjamin Wriedt taking samples from the storage vessel of a photoreactor.
© Fraunhofer IGB
Dr. Benjamin Wriedt taking samples at the storage vessel of a photoreactor.

Challenge: Energy-intensive elimination of micropollutants

As a precautionary measure and due to new limit values for micropollutants [1, 2], numerous wastewater treatment plants are currently upgraded to include a so-called fourth treatment stage. After mechanical, biological and chemical treatment, this stage aims to remove the remaining residues of pharmaceuticals, pesticides or industrial chemicals. However, the processes predominantly used, ozonation and activated carbon adsorption, are quite energy-intensive.


Solution: Energy-efficient technology for the degradation of trace substances

A potentially more energy-efficient and, in terms of carbon footprint, more favorable method is sunlight-driven photocatalytic pollutant oxidation. Therefore, as part of the BMBF-funded research project CatMemReac, a water technology for the removal of trace organic substances or micropollutants (OMPs) from water (wastewater/groundwater) using a solar-photocatalytic membrane reactor (CatMemReac) is being adapted and demonstrated in a collaboration between the Fraunhofer Institutes IGB and ISI and Tel Aviv University, Israel.

Reactor setup inside the irradiation chamber
© Fraunhofer IGB
Reactor setup inside the irradiation chamber
Top view on reactor in irradiation direction (without nickel foam).
© Fraunhofer IGB
Top view on reactor in irradiation direction (without nickel foam).

Hybrid system combining photocatalysis with membrane filtration

CatMemReac is a hybrid system, combining both photocatalysis and an upstream low-pressure membrane filtration in a compact design. The photocatalysis-based advanced oxidation process (AOP) will be catalyzed by solar and solar-powered light emitting diodes (LEDs). Thus, harmful trace substances such as the pharmaceutical carbamazepine can be eliminated without residues.

Novel materials, heterogeneous nanocatalysts and metal foam with low lifecycle costs are deployed in eco-efficient processes with low energy demand, thus anticipated to reduce the carbon-footprint of conventionally energy-intensive water treatment processes. Joint definition of target parameters will be followed by catalyst production, characterization and design and piloting of the new treatment method.


Investigation of photocatalytic degradation

Currently, reactors with high-power LED arrays and titanium dioxide-coated nickel foams are being tested for the photocatalytic degradation of pollutants. At Fraunhofer IGB, new, tailor-made photoreactors have already been designed and characterized in terms of reaction engineering in order to gain access to dimensionless process parameters. On this basis, the performance of different systems can already be objectively compared on a laboratory scale, allowing an optimized concept for scale-up.


Measurement of treatment performance by actinometry and determination of oxidation potential

Necessary tools for the understanding and systematic optimization of photocatalytic processes are actinometry and the determination of the oxidation potential by free radicals. The experimental design and execution of these measurements are performed at the IGB. The external photonic efficiency and quantum yield parameters can be used to model the maximum possible treatment performance.

Actinometry is a chemical measurement technique to determine the photon flux available in the reaction volume including wavelength resolution. [3] It can be used to model kinetics, select catalysts with higher efficiency, and perform process simulations for optimization. [4, 5]

The determination of the scavenging potential quantifies the next step in the purification process by measuring the concentration of radicals that can attack and destroy the molecular structure of micropollutants. Combined with actinometry, efficiency sinks can thus be found and eliminated.

Titanium dioxide-coated nickel foams (left) are activated by high-power LEDs. This promises higher available photon fluxes and efficiencies (right), improving the carbon footprint.
© Fraunhofer IGB
Titanium dioxide-coated nickel foams (left) are activated by high-power LEDs. This promises higher available photon fluxes and efficiencies (right), improving the carbon footprint.
Prof. Hadas Mamane working in the laboratory with the LED system.
© Tel-Aviv University
Prof. Hadas Mamane working in the laboratory with the LED system.

Demonstration and evaluation at a wastewater treatment plant in Israel

In the CatMemReac project, photochemical reactor characterization on a laboratory scale was successfully completed. The next step will be the construction of a pilot-scale demonstrator plant for use in an on-site wastewater treatment plant in Israel in early 2023.

The experimental data collected from this pilot application will be used to conduct a life cycle analysis (LCA) with a focus on the CO2 balance. This implicitly deduces to what extent greenhouse gas emissions can be saved by implementing photocatalytic wastewater treatment as a fourth treatment stage compared to the state of the art.

Parallel to the construction of the demonstrator, further parameters effecting treatment efficiency are being investigated. These include e.g., the influence of the pore size of the nickel foam, the irradiation time and intensity in the reaction chamber, as well as the degradation efficiency as a function of the water and trace substance matrix.

Advantages and services offer

Our new approach

The innovative and unique aspects will include:

  • Degradation of OMPs using solar-catalytic membranes that minimize energy demand and eco-efficient process operation for membrane cleaning and reuse of effluent
  • Development and application of a new tool for evaluation of the carbon footprint over the life cycle of emerging water treatment technologies in early stages of technological development
Dipl.-Ing. Christiane Chaumette in the laboratory.
© Fraunhofer IGB
Dipl.-Ing. Christiane Chaumette in the laboratory.

Treatment of sample wastewater from customers

Energy efficiency in the treatment of wastewater is not only of elementary importance for municipal wastewater treatment plants with regard to economic efficiency, but also for all companies in which polluted water is produced.

When deciding on the right technology to suit individual customer needs, the IGB can offer technology- and company-independent support. Energy demand, treatment time and method efficiency can be evaluated in laboratory tests with sample wastewater from customers to derive a recommendation on the appropriate treatment process. Furthermore, Fraunhofer IGB offers the determination of the oxidation potential and the available photon flux in a plant as service measurements.


[1] Proposal for a DIRECTIVE OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL concerning urban wastewater treatment (recast), European Commission, 2022; 26.10.2022 COM (2022) 541 final, ANNEXES 1 to 8

[2] Verordnung des UVEK zur Überprüfung des Reinigungseffekts von Massnahmen zur Elimination von organischen Spurenstoffen bei Abwasserreinigungsanlagen, Das Eidgenössische Departement für Umwelt, Verkehr, Energie und Kommunikation (UVEK), vom 3. November 2016 (Stand am 1. Dezember 2016), 814.201.231

[3] Wriedt, B.; Ziegenbalg, D. (2018) Experimental determination of photon fluxes in multilayer capillary photoreactors, ChemPhotoChem 2(10), DOI: 10.1002/cptc.201800106

[4] Wriedt, B.; Ziegenbalg, D. (2020) Adapting actinometry procedures for use in intensified photoreactors, Chemie Ingenieur Technik 92(9)

[5] Wriedt, B.; Ziegenbalg, D. (2021) Application limits of the ferrioxalate actinometer, ChemPhotoChem 5(10), DOI: 10.1002/cptc.202100122

Further publications to consider

V. Kumar, D. Avisar, V.L. Prasanna, Y. Betzalel, H. Mamane (2020): Rapid visible-light degradation of EE2 and its estrogenicity in hospital wastewater by crystalline promoted g-C3N4, Journal of Hazardous Materials, p.122880.

I. Horovitz, V. Gitis, D. Avisar, H. Mamane (2020): Ceramic-based photocatalytic membrane reactors for water treatment–where to next?, Reviews in Chemical Engineering.

T. Peng, J. Pulpytel, I. Horovitz, A.K. Jaiswal, D. Avisar, H. Mamane, J.A. Lalman, F. Arefi-Khonsari (2019): One‐step deposition of nano‐Ag‐TiO2 coatings by atmospheric pressure plasma jet for water treatment: Application to trace pharmaceutical removal using solar photocatalysis, Plasma Processes and Polymers, 16 (6), 1800213.

I. Horovitz, D. Avisar, E. Luster, L. Lozzi, T. Luxbacher, H. Mamane (2018): MS2 bacteriophage inactivation using a N-doped TiO2-coated photocatalytic membrane reactor: Influence of water-quality parameters, Chemical Engineering Journal, 354, 995-1006.

A. Dandapat, I. Horovitz, H. Gnayem, Y. Sasson, D. Avisar, T. Luxbacher, H. Mamane (2018): Solar Photocatalytic Degradation of Trace Organic Pollutants in Water by Bi (0)-Doped Bismuth Oxyhalide Thin Films, ACS omega, 3(9), 10858-10865.

E. Luster, D. Avisar, I. Horovitz, L. Lozzi, M.A. Baker, R. Grilli, H. Mamane (2017): N-Doped TiO2-Coated Ceramic Membrane for Carbamazepine Degradation in Different Water Qualities, Nanomaterials, 31, 7(8). E206. doi: 10.3390/nano7080206.

I. Horovitz, D. Avisar, R. Grilli, A.D. Enevoldsen, D. Di Camillo, M.A. Baker, L. Lozzi, H. Mamane (2016): Carbamazepine degradation using a N-doped TiO2 coated photocatalytic membrane reactor: influence of physical parameters, Journal of Hazardous Materials, 310, 98–107.

N. Meorn, V. Blass, Y. Garb, Y. Kahane, G. Thoma (2016): Why Going beyond Standard LCI Databases is Important: Lessons From A Meta-Analysis of Potable Water Supply System LCAs, International Journal of Life Cycle Assessment, 21(8); 1134–1147.

N. Meorn, V. Blass, G. Thoma (2020): Selection of the Most Appropriate Life-cycle Inventory Dataset: New Selection Proxy Methodology and Case Study Application, Journal of Life Cycle Assessment 25: 771–783.

N. Meorn, V. Blass, G. Thoma (2020): A National Level LCA of a Water Supply System in a Mediterranean-Semi-Arid Climate – Israel as a Case Study, International Journal of Life Cycle Assessment 25: 1133–1144.

I. Reim, B. Wriedt, Ü. Tastan, D. Ziegenbalg, M. Karnahl (2018): Impact of the Type of Reactor and the Catalytic Conditions on the Photocatalytic Production of Hydrogen Using a Fully Noble‐Metal‐Free System, ChemistrySelect 3, 2905–2911.

S. Triemer, M. Schulze, B. Wriedt, R. Schenkendorf, D. Ziegenbalg, U. Krewer, A. Seidel-Morgenstern (2021): Kinetic analysis of the partial synthesis of artemisinin: Photooxygenation to the intermediate hydroperoxide, Journal of Flow Chemistry 11, 641–659.

Project information

Project titel

CatMemReac – CO2 reduction in the oxidation of micropollutants – energy-intensive vs. novel solar-based processes


Project duration

July 2021 – June 2024


Project partners


We would like to thank the German Federal Ministry of Education and Research (BMBF) for funding the project “CatMemReac“, promotional reference 02WIL1605.

Federal Ministry of Education and Research.

This is part of the funding program for German-Israeli technology cooperation Cogeril as part of the BMBF strategy “Forschung für Nachhaltigkeit (FONA)“.