Seasonal variation of elements composition and biomethane in brown macroalgae. (February 2018)

• Record Type: Journal Article
• Authors: Ometto, Francesco; Steinhovden, Kristine B.; Kuci, Hana; Lunnbäck, Johan; Berg, Andreas; Karlsson, Anna; Handå, Aleksander; Wollan, Håvard; Ejlertsson, Jörgen
• Is Part Of: Biomass and bioenergy. Volume 109(2018)
• Page Start: 31
• Page End: 38
• Publication Date: 2018-02
• Subjects: Seaweed -- Algae composition -- Biofuels -- Anaerobic digestion; Biomass energy -- Periodicals; Biomass -- Periodicals; Energy-Generating Resources -- Periodicals; Bioénergie -- Périodiques; 333.9539
• DOI: 10.1016/j.biombioe.2017.11.006
• Languages: English
• ISSNs: 0961-9534

Abstract

Abstract: To investigate the effect of seasonal variation on macroalgae biomass characteristics and its related energy content, four different algae species, two from the Fucales order ( Fucus vesiculosus and Ascophyllum nodosum ), and two from the Laminariales order ( Saccharina latissima and Alaria esculenta ), were harvested during spring, summer, autumn and winter over one year. The biomethane potential and the elemental composition were determined for all samples. Both Fucales species showed low biodegradability (<30%) with methane yields consistently below 20 Nm 3 per wet tonne. Laminariales species, however, allowed up to 80% biodegradation efficiency, with methane yields varying between 20 and 70 Nm 3 per wet tonne depending on the harvesting season. For each of the four algae the biomass concentrations of potassium, phosphorus, calcium, magnesium, sodium, sulphur, aluminium and iron was higher during spring/summer compared to autumn/winter. For heavy metals, variation was seen mainly for arsenic with higher values during autumn/winter. The highest values were observed for Laminariales (30–120 mg/kg total solids). Modelling the co-digestion of each algae with municipal wastewater sludge showed Laminariales species having the greatest potential as a profitable substrate for additional biomethane production generating up to 0.38 million Euro. However, seasonal variation could affect this expected income over 60% due to fluctuation in biomethane yields and biodegradability efficiency. Furthermore, the additional loading of cadmium and arsenic into the AD process suggested possible limitation for digestate utilisation in arable lands. Highlights: Methane yields of Laminariales species varied between 20 and 70 Nm 3 /ton wet biomass. Fucales species showed methane yields consistently below 20 Nm 3 /ton wet biomass. Laminariales contain between two to four times more phosphorus than Fucales. For heavy metals, arsenic was the main element in all algae (20–120 mg/gTS). Modelling AD of algae-wastewater sludge supported algae as valuable feedstock.