Can marine macro algae be a potential feedstock for bioethanol production?

Leor Korzen, Department of Zoology, Tel Aviv University, Tel Aviv, Israel
Indra Neel Pulidindi, Chemistry, Bar Ilan University, Ramat Gan, Israel
Aharon Gedanken, Chemistry, Bar Ilan University, Ramat Gan, Israel
Alvaro Israel, Oceanography, IOLR, Haifa, Israel
Avigdor Abelson, Department of Zoology, Tel Aviv University, Tel Aviv, Israel

Ulva rigida, a common green seaweed, was examined as a feedstock for the production of bioethanol in a simultaneous saccharification and fermentation (SSF) process carried out under sonication.  Sonication (40 kHz, 120 W) provided a faster way relative to the conventional incubation process, for the simultaneous release of glucose from Ulva rigida and its conversion into bioethanol.  Within 3 h, 196 ± 2.5 mg glucose per gram of dry weight of biomass was obtained. 106 ± 0.74 mg bioethanol per gram of dry algae were produced in the SSF process under sonication.  The SSF process parameters like the solid consistency, enzyme loading and the carbohydrate content of the algae were optimized.  Thus a sonication based simultaneous saccharification and fermentation process for the production of bioethanol from Ulva rigida was developed.  A maximum of 10.6 wt.% of ethanol (on dry wt. basis) was obtained under sonication in 4 h.

The salient features of the process include (i) no requirement of chemical pretreatment of the biomass, (ii) only one stage of operation and (iii) exclusive production of glucose as the sole sugar as a result of enzymatic saccharification and (iv) faster production of glucose from Ulva rigida and simultaneous conversion of glucose to ethanol. The results obtained will be discussed in detail in the 80th Annual meeting of the Israel Chemical Society.