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.
