Utilization of Seawater in the Pretreatment and Saccharification of Seaweed

Abstract

The growing need to cater to the energy demand coupled with the urge to mitigate greenhouse gas footprint in the energy sector has led to the exploration of biofuels, such as bioethanol, as a renewable and sustainable source. However, the desire for freshwater in bioethanol production is extremely high and hence it is considered as a high water footprint product. With the scarcity of ever-depleting fresh water resources and its huge consumption in biorefineries, it has become difficult to use fresh water for bioconversions. The use of abundantly available seawater as a substitute for freshwater was suggested to reduce the water footprint of bioethanol production. Furthermore, bioethanol production using seaweeds or macroalgal resources has shown great promise and significance in global sustainable development. Therefore, in the present study, pretreatment and saccharification of Chaetomorpha sp., a green seaweed, was carried out using seawater based reaction medium. The optimal pretreatment conditions were obtained using the microwave at 6.681% substrate loading, 1.487% NaOH and 7.724 min duration, which resulted in a maximum reducing sugar yield of 0.196 g/g. These findings reveal that seawater can produce comparably digestible solids to those of fresh water and can be used as an alternative to fresh water usage in biofuel production.