Biohythane production from marine macroalgae Sargassum sp. coupling dark fermentation and anaerobic digestion

Abstract

Potential biohythane production from Sargassum sp. was evaluated in a two stage process. In the first stage, hydrogen dark fermentation was performed by Caldicellulosiruptor saccharolyticus. Sargassum sp. concentrations (VS) of 2.5, 4.9 and 7.4 g L−1 and initial inoculum concentrations (CDW) of 0.04 and 0.09 g L−1 of C. saccharolyticus were used in substrate/inoculum ratios ranging from 28 to 123. The end products from hydrogen production process were subsequently used for biogas production. The highest hydrogen and methane production yields, 91.3 ± 3.3 L kg−1 and 541 ± 10 L kg−1, respectively, were achieved with 2.5 g L−1 of Sargassum sp. (VS) and 0.09 g L−1of inoculum (CDW). The biogas produced contained 14–20% of hydrogen. Potential energy production from Sargassum sp. in two stage process was estimated in 242 GJ ha−1 yr−1. A maximum energy supply of 600 EJ yr−1 could be obtained from the ocean potential area for macroalgae production. The highest hydrogen and methane production yields, 91.3±3.3 L kg-1 and 541±10 L kg-1, respectively, were achieved with 2.5 g L-1 of Sargassum sp. (VS) and 0.09 g L-1of inoculum (CDW). The biogas produced contained 14 to 20% of hydrogen. Potential energy production from Sargassum sp. in two stage process was estimated in 242 GJ ha-1yr-1. A maximum energy supply of 600 EJ yr-1 could be obtained from the ocean potential area for macroalgae production.Portuguese Science Foundation (FCT) and European Social Fund (ESF, POPH-QREN) / (SFRH/BPD/82000/2011) / project FCOMP-01-0124-FEDER-027914 (PTDC/AAG-TEC/3048/2012), financed by FEDER through COMPETE – Programa Operacional Factores de Competitividade; and FCT Strategic Project PEst-OE/EQB/LA0023/2013, the FCT Project RECI/BBB-EBI/0179/2012 and the Project ‘‘BioEnv – Biotechnology and Bioengineering for a sustainable world’’, REF. NORTE-07-0124-FEDER-000048, co-funded by the Programa Operacional Regional do Norte (ON.2 – O Novo Norte), QREN, FEDER