Second generation ethanol made from coir husk under the biomass Cascade approach

Abstract

Brazil is the largest world producer and consumer of coconut water with approximately two billion fruits, where 70% is for water production. Therefore, a large amount of waste is generated: the coir husk, which represents approximately 1.75 kg per fruit unit. This biomass presents 35% cellulose in its composition, which makes the coir husk a good option for the raw material for second-generation (2 G) ethanol production. In this study, the coir husk was chemically pretreated using four different treatments. The 2 G ethanol production was studied considering two different processes, using separated hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF). The pretreatment used a solution containing sodium chlorite at 10% of the acetic acid and the SSF process was the better method for 2 G ethanol production from coir husk, yielding 52.7 L ethanol/ton of biomass. Thus, the coir husk can be considered an alternative for the production of 2 G ethanol, with all the environmental and social advantages of such an approach, such as occupying precious space in the landfills and taking 12 years to decompose.

Keywords:

• 2G ethanol
• coir husk
• pretreatment

Acknowledgments

The authors are grateful for the financial support of Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) (Grant No. 2017/24274-3) and the Brazilian agency Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) for the Bronzato, G. R. F. fellowship.