Process intensification towards sustainable wastewater treatment with phototropic biofilms

Projektinformationen

Inlight

ID Finanzhilfevereinbarung: 101109290

DOI

10.3030/101109290

Projekt abgeschlossen

EK-Unterschriftsdatum 10 Mai 2023

Startdatum 1 Februar 2024

Enddatum 31 Januar 2026

Finanziert unter

• Marie Skłodowska-Curie Actions (MSCA)

Gesamtkosten

Keine Daten

EU-Beitrag

€ 203 464,32

Koordiniert durch

TECHNISCHE UNIVERSITEIT DELFT
Netherlands

Periodic Reporting for period 1 - Inlight (Process intensification towards sustainable wastewater treatment with phototropic biofilms)

Berichtszeitraum: 2024-02-01 bis 2026-01-31

Zusammenfassung vom Kontext und den Gesamtzielen des Projekts

Wastewater treatment is essential for public health and environmental protection, yet conventional treatment technologies rely heavily on mechanical aeration, which consumes large amounts of energy and leads to substantial greenhouse gas emissions. Aeration alone can account for up to 70% of the operational energy demand of modern wastewater treatment plants. Reducing this energy demand while maintaining high treatment efficiency is a key priority for the European Union, in line with the Water Framework Directive and EU climate neutrality goals. This project addresses the challenge by exploring light-driven wastewater treatment using photogranules, which are compact microbial aggregates composed of phototrophic microorganisms, such as algae and cyanobacteria, and heterotrophic bacteria. In these systems, phototrophs use light to convert carbon dioxide into oxygen, which is then consumed by heterotrophic bacteria for wastewater treatment, potentially eliminating the need for mechanical aeration. The overall objective is to improve the fundamental understanding of the relationship between light absorption by photogranules and their oxygen production to provide a scientific basis for designing energy-efficient systems. By combining concepts from chemical engineering, microbiology, and photophysics, the project aims to identify the conditions under which these light-driven processes can contribute to more sustainable wastewater treatment at larger scales, creating a pathway toward energy-neutral water infrastructure.

Arbeit, die ab Beginn des Projekts bis zum Ende des durch den Bericht erfassten Berichtszeitraums geleistet wurde, und die wichtigsten bis dahin erzielten Ergebnisse

The work performed during this period was characterized by a multi-scalar approach ranging from international field coordination to the development of advanced experimental and modeling tools. A significant achievement involved consolidating the emerging field of photogranulation through the co-organization of an international conference, which facilitated the the effort for the unification of terminology and the creation of a collaborative framework to define photogranules. Within this effort, the project introduced critical benchmarking studies that allow for a meaningful comparison between photogranule-based systems, aerobic granular sludge, and algal treatment processes by explicitly accounting for the energy trade-offs between aeration and light supply. On a technical level, a novel experimental methodology was developed to quantify light absorption within complex, light-scattering media. Since photogranules are irregular and porous, making light interaction difficult to predict, a specialized reactor was designed using chemical actinometry in a transparent external jacket. This allowed for the accurate measurement of light attenuation without disturbing the biological process, extending the use of actinometry to highly scattering biological systems. This methodological breakthrough was further complemented by the design of new reactor supports specifically engineered to increase light efficiency within photobioreactors. Finally, these experimental results were integrated into a predictive model that relates light input directly to oxygen generation. By providing a direct link between absorbed light and biological activity, this model offers a scientific foundation for designing more energy-efficient wastewater systems where oxygen production can be precisely tuned to treatment demands.

Fortschritte, die über den aktuellen Stand der Technik hinausgehen und voraussichtliche potenzielle Auswirkungen (einschließlich der bis dato erzielten sozioökonomischen Auswirkungen und weiter gefassten gesellschaftlichen Auswirkungen des Projekts)

The results of this project move significantly beyond the current state of the art by replacing empirical "trial-and-error" approaches with a rigorous, physics-based framework for light-driven wastewater treatment. While existing research in photogranulation often struggles with the unpredictable nature of light interaction in dense microbial aggregates, this project introduced a pioneering experimental methodology using chemical actinometry within a specialized jacketed reactor. This allowed for the first precise quantification of light absorption in highly scattering, irregular biological media and its direct relation to oxygen generation, effectively moving past the limitations of standard models that fail to account for the complex internal structures of photogranules. By coupling these measurements with biological activity data, the project developed a predictive model that directly links light input to oxygen generation. This represents a fundamental shift in reactor design, enabling thebetter tuning of photosynthetic oxygen production to meet specific metabolic demands, a level of control previously unattainable in algal-bacterial systems.

Furthermore, the project addressed a critical gap in the field’s maturity through the development of a comprehensive benchmarking framework and the unification of scientific terminology. Until now, the lack of standardized definitions and metrics made it difficult to compare the performance of photogranules against established technologies like aerobic granular sludge or traditional algal ponds or among each other. By introducing a benchmark that explicitly account for organic carbon removal per the energy input (e.g. mechanical aeration and light delivery) per reactor volume, the project provides the first transparent metric for evaluating the true "net energy" benefit of light-driven systems. This high-level coordination, including the preparation of a collaborative perspective paper and the organization of an international conference, is the result of an efford to establish a common language for the global research community, providing the structural foundation necessary for the field to transition from fundamental research toward industrial application.