A fundamental study on anaerobic digestion of sea lettuce

Ulva species called sea lettuce, a kind of green algae, often propagate explosively in eutrophic shallow water areas. When a lot of sea lettuces die and accumulate on the sea bottom or beach, the large amount of their bodies are spoiled and cause destructive damages to benthic ecosystem. In this paper, the authors focus on an anaerobic digestion as one of the utilization techniques for such bad quality sea lettuces. They carried out a continuous commitment experiment using a jar fermentor filled with sewage sludge. The result showed that the methane gas constantly produces about 25 days after the beginning of commitment of sea lettuce pastes. They also performed a batch-processing experiment using some different pretreatment sea lettuces. The result suggested that the methane gas yield from washed and ground sea lettuce bio mass is about 180 ml g^-1 (volatile solid based), and that from non-pretreated biomass is about 70% of it