Abstrakt

Macroalgae can be seen as a renewable feedstock for the production of biofuels in many coastal areas around the World and especially in Baltic Sea region where the eutrophication is particularly troublesome. The investigation of anaerobic digestion technologies for extracting inexhaustible bioenergy from seaweed was conducted in many research institutions mainly in laboratory scale. Although seaweeds seem to have a great potential as a feedstock in anaerobic digestion due to high biomass yields and lack of competition with terrestrial plants on limited agricultural land, their potentially high heavy metals content and other impurities (like sand and plastics) creates significant problems for the digestion process, but also for the further use of the digestate. Due to high levels of contaminants, it is not always possible to directly use the cast seaweed as a substrate for biogas production. The micro and macro elements uptake by algae strongly depends on factors as water salinity, characteristics of habitats (e.g. presence of an nearby industrial area or existence of an estuary whose waters might carry additional nutrient loads from urban and agriculture areas). The main limiting factor of a digestate utilisation as an organic fertiliser is the heavy metals concentration but the main process issues during anaerobic digestion are caused by the presence of sand in the feedstock. Collected seaweed biomass (especially from sandy beaches) very often contains sand, which can negatively effect the durability of bioreactors and other biogas plant equipment. Pre-treatment of the collected seaweed is essential for the anaerobic digestion process safety and efficient operation of the biogas plant. Furthermore, different stages of pre-treatment as well as the combination of pre-treatment methods can greatly increase the quality of the methane yield. Present study focuses on pre-treatment methods case reducing sand contents in seaweed feedstock.

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