Bio-fuel from anaerobic co-digestion of the macro-algae Ulva lactuca and Laminaria digitata
2012
Sarker, S., Aarhus Univ., Tjele (Denmark). Dept. of Engineering | Bruhn, A., Aarhus Univ., Silkeborg (Denmark). Dept. of of Bioscience | Ward, A.J., Aarhus Univ., Tjele (Denmark). Dept. of Engineering | Moeller, H.B., Aarhus Univ., Tjele (Denmark). Dept. of Engineering
World’s energy crisis is becoming increasingly critical when emission from fossil fuel due to the rapid expansion of population and their growing energy consumption is considered. This leads us to reassess the potential of already available renewable energy sources and to step further in the exploration of marine biomass. So far, the progress in treating different groups of algae as a source of energy is promising although their utilization is still in early days. In the present study, green seaweed, Ulva lactuca and brown seaweed Laminaria digitata was co-digested with cattle manure at mesophilic (35±2 deg C) and thermophilic (50±2 deg C) condition for testing the biogas production at lab scale continuous reactors (3.2 liters working volume). Ulva was grown and harvested in Danish algae center and washed to reduce salt concentration and subsequently macerated to facilitate feeding in the digesters. Laminaria, however, was harvested from the sea (Fornæs, Denmark) although similar pretreatment method as Ulva was followed. The results show that the methane yield of Laminaria from mesophilic anaerobic digestion was fairly stable (average 138 lCH4/kgVSadded) over a different type of feeding. Methane generation from thermophilic reactors both for Ulva and Laminaria, on the other hand, were significantly varied, one opposite to the other, as the feeding rate varied. While the thermophilic treatment of Laminaria produced an average of 142 L/kgVS, Ulva yielded around 122 L/kgVS. Overall, it was found that algae are very interesting substrates for utilizing as gaseous bio-fuel through anaerobic co-digestion with cattle manure.
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