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Advances in the pretreatment of brown macroalgae for biogas production

Thompson, Terrell M., Young, Brent R., Baroutian, Saeid
Fuel processing technology 2019 v.195 pp. 106151
Phaeophyceae, bioavailability, biofertilizers, biogas, biotransformation, case studies, energy balance, fermentation, fossil fuels, gas production (biological), greenhouse gas emissions, lignin, macroalgae, methane, polysaccharides, saccharification, sewage sludge
Brown macroalgae are an attractive, untapped resource and a favourable alternative for conventional fossil fuels, given their low lignin and high polysaccharide content. However, the restricted bioavailability of structurally complex carbohydrates for digestion, results in a low biomethane potential. This paper reviews the various pretreatment technologies explored to optimise saccharification prior to fermentation, categorised as: physical, biological, chemical, thermal and a combination of methods. A techno-economic assessment was conducted to evaluate the commercial viability of each process. Hydrothermal pretreatment proves the most promising technique for brown algae application, since it improves methane productivity, carries a net positive energy balance and generates a bio-fertilizer, while mitigating greenhouse gas emissions. Pilot scale research is necessary to evaluate the feasibility of full-scale implementation for brown algae bioconversion. A case study of the Cambi™ process concludes the paper as it exemplifies the successful utilisation of hydrothermal pretreatment for sewage sludge biogas production.