Bioethanol production from lignocellulosic and macroalgae feedstock and its separation by membrane distillation: Effect of pretreatments on reducing sugar and bioethanol yield

The rapid depletion of fossil fuels, increasing environmental pollution and fluctuating oil pricing have led to the search for sustainable energy sources such as biofuels from biomass. This thesis systematically examines the bioethanol production using a series of steps, namely, pretreatment, hydrolysis, fermentation and membrane-based bioethanol separation. The feedstock used for bioethanol production were lignocellulosic biomass (potato peel) and macroalgae (Laminaria japonica – brown macroalgae). Due to the different cellular compositions of these feedstocks, the potota peel waste was enzymatically pretreated with laccase enzyme (a copper containing delignification enzyme) whereas macroalgae was pretreated with hydrothermal pretreatment to produce reducing sugar. Reducing sugar was fermented to produce bioethanol. The purification of bioethanol was performed by a novel method using direct-contact membrane distillation (DCMD) for effective bioethanol separation from fermenting broth (produced after fermentation). A polytetrafluoroethylene (PTFE) membrane was used in the DCMD system.