FEMAK is the abbreviation for a mobile micro-algae culture facility (=MAK) for research and development (= R&D) purposes.
At the site of the wastewater treatment plant in Plön it will be demonstrated how freshwater microalgae cultivation can be coupled with water remediation and wastewater treatment.
A microalgae bioreactor made of closed glass - tube module systems uses natural light for effective algae production. The system is operated with effluent water from the Plön wastewater treatment plant and is enriched with oxygen by the growth of the biomass. Excess nutrients (mainly phosphorus and nitrogen) are specifically reduced and only pure, oxygen-enriched water is returned to Kleiner Plöner See. The extent to which this measurably benefits water quality is part of the extensive monitoring of results.
The influx of the microalgae-remediated water into the lake's ecosystem should result in a reduction of foul gas formation, improved mixing of "barrier layers" and reduced phosphate re-suspension. If the research project is successfully implemented, the model could be transferred for remediation purposes of many species.
Background and challenge:
The FEMAK research project addresses the pressing issue of water quality, in particular the challenge posed by high phosphate concentrations in lakes, which promote algae growth and lead to oxygen deficiency. The project addresses this problem with an innovative solution for the oxygenation of lake sediments.
The EU Water Framework Directive sets the goal of achieving good ecological status for all water bodies. Phosphate is considered a limiting factor for the growth of algae, but is present in high concentrations in many lakes. Both external inputs and internal fertilisation contribute to this problem. Iron-phosphate complexes dissolve in oxygen-depleted layers, releasing phosphate and promoting algae growth. These processes intensify during winter and summer stagnation, with the decomposition of dead biomass further reducing oxygen levels and releasing methane, which disrupts the ecological balance and jeopardises organisms.
Innovative solutions:
The FEMAK project aims to utilise oxygen-rich, nutrient-free water from an algae culture system for the continuous oxygen supply of lake sediments. A fast-sinking mixed algae culture in a photobioreactor was developed for this purpose. The Kleine Plöner See in Schleswig-Holstein serves as a model lake, whose phosphorus re-dissolution and oxygen dynamics are being analysed in detail. These investigations will be expanded in summer 2024 to include methane and other measurements in order to gain a comprehensive understanding of the material cycles and probably greatly underestimated methane release from stagnant waters.
Technical realisation:
As part of the project, a mobile mass algae culture plant (MAK) will be established at the Plön wastewater treatment plant. This plant integrates the production of a mixed microalgae culture into the wastewater treatment process. In contrast to conventional batch cultivation, the MAK concept with plug-flow reactors enables continuous treatment of the process water. The MAK consists of a photobioreactor combined with a sedimentation tank for efficient algae recirculation and harvesting.
Project objectives and research focus:
The main objectives of the project include the year-round production of nutrient-free, cold and oxygen supersaturated wastewater and the investigation of algal biomass production as a nutrient and pollutant sink. Different operating modes of the bioreactor will be analysed in order to maximise the efficiency of algae cultivation and to explore possibilities for heat generation. In addition, the plant will serve as a platform for investigating various applications for the biomass produced.
Overall, the FEMAK project aims to develop innovative solutions for wastewater treatment through the use and further development of algae cultivation technologies in order to reduce the environmental impact of wastewater and promote sustainable resource utilisation.
In the FEMAK research project, it becomes clear once again how the Blue Bioeconomy can solve concrete environmental problems. The pilot plant is intended to demonstrate how sustainable improvement of water quality can be achieved with the help of microalgae. The Kleine Plöner See in Schleswig-Holstein serves as the model water body.
Since industrialization, lakes and other open water bodies have suffered from high phosphate levels, which stimulate uncontrolled cyanobacteria and algae growth. When these algae die off, large amounts of oxygen are removed from the ecosystem, which can lead to phosphate release, especially in deeper water layers. This process results in oxygen deficiency, internal phosphate release from the sediment and even methane release, a vicious cycle that endangers ecological balance.
FEMAK pursues an innovative approach: a microalgae mixed culture is cultivated in a self-constructed mass algae cultivation system (MAK), producing oxygen-rich, nutrient-poor water. This water is used specifically to aerate the lake sediments. As a result, phosphate release is inhibited and the oxygen supply in the lake is significantly improved.
The mobile MAK at the Plön wastewater treatment plant site uses a photobioreactor with a connected settling tank. Unlike conventional algae systems, the system does not operate in batch mode, but in continuous flow operation. This allows larger volumes of water to be treated continuously, an important step forward for technical feasibility.
In addition to the development and testing of the system, the research focuses on:
• the seasonally stable production of oxygen-supersaturated water,
• the role of microalgae as a nutrient and pollutant sink,
• increasing the efficiency of different operating modes,
• potential heat utilization, and
• the use of algae biomass as a resource.
Prof. Dr. Rüdiger Schulz
Botanical Institute, Christian-Albrechts-Universität zu Kiel
• Christian-Albrechts-Universität zu Kiel
• LimnoSystem – Biotechnologische Anlagen
• FlowConcept GmbH
FEMAK represents a new generation of water restoration: ecological, innovative and microalgae-based.
