JMSE, Vol. 13, Pages 1880: Seasonal Dynamics of Microalgal Biomass and Its Biomethanation Potential: A Case Study from the Bay of Gdansk, Poland

Journal of Marine Science and Engineering doi: 10.3390/jmse13101880

Authors:
Marcin Dębowski
Marta Kisielewska
Joanna Kazimierowicz
Marcin Zieliński

This study aimed to evaluate the effect of seasonal dynamics of phytoplankton biomass in the Bay of Gdansk (Southern Baltic Sea, Poland) on its usability for anaerobic digestion. Biomass samples were collected between May and October (2023–2024) for quantitative, taxonomic, and chemical analyses as well as for anaerobic digestion in mesophilic periodical bioreactors. Study results demonstrated substantial seasonal variations in the taxonomic composition of phytoplankton, with green algae and dinoflagellates prevailing in the spring, cyanobacteria in the summer, and diatoms in the autumn. These fluctuations were also reflected in the chemical composition of the biomass and its anaerobic digestion efficiency. The highest methane yield of 270 ± 13 mL CH4/g VS and its highest production rate reaching 32.5 ± 1.6 mL CH4/g VS·d were recorded in August, i.e., in the period of cyanobacteria predominance with the maximal contents of TOC (51.4 ± 2.1% TS), sugars (599 ± 42 mg/g TS), and lipids (126 ± 13 mg/g TS) in the biomass. In contrast, the lowest biomethanation efficiency was determined in October under diatom prevalence. A strong correlation was found between taxonomic, structural, and chemical properties of the substrate, and anaerobic digestion efficiency. This study’s findings underscore the enormous potential of phytoplankton biomass from summer blooms for energy production as a crucial element of sustainable management of coastal ecosystems and the circular economy.

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Marcin Dębowski www.mdpi.com