Alissandra Pauline Bautista Mariano. Feasibility study of bioethanol production from coconut pulp residue by using two-step pretreatment techniques. Master's Degree(Master of Engineering Renewable Energy Engineering). . : Maejo University, 2020.
Feasibility study of bioethanol production from coconut pulp residue by using two-step pretreatment techniques
Abstract:
Increasing concern over depleting fossil fuel and greenhouse gas limits ds to more interest in renewable fuel created from biomass source sugars, starches and lignocellulosic materials. The production of ethanol from mass materials is receiving more attention especially from agricultur biorefinery wastes. The application of biorefinery processes and its improvements are imum significance to meet the aim towards a sustainable economy bio-resources. Coconut is widely cultivated in Southeast Asia especially in humid
tropics such as India, Philippines, and Thailand. Along the process for its oil and milk, large amount of coconut pulp residue is discarded as waste. Therefore, coconut pulp residue was evaluated in this study as potential feedstock for bioethanol production. Two types of waste generated from extraction of coconut oil was examined: pure pulp residue (PPR) and combined pulp residue and sEed coat (CPRS). Four different pretreatment designs were applied and studied to determine the optimal sugar yield from coconut pulp residue. The pretreatment design included combination of hydrothermal pretreatment and post-alkali/acid treatment. The post-
alkali/acid pretreatment was aided by oven or autoclave to foresee the effects of tow and high temperatures on coconut pulp residues sugar release. The response surface methodology was utilized to determine the optimized condition from the 4 'sets of pretreatment design. Hydrolysates from PPR and CPRS, with the highest sugar concentration from the optimized two-step pretreatment and hydrolysis, was selected and proceeded to bioethanol fermentation for 72 hours. From the experimental results, it was shown that the maximal total and reducing sugar concentration of PPR was 245.76 g/L and 203.81 g/L while in CPRS it was 302.43 g/L and 238.57 g/L, respectively. The optimal two-step pretreatment for PPR was 60 minutes pre-hydrothermal treatment time followed by post-oven-acid treatment of 2% HzSO, at 60'C for 24 hours. Similar pretreatment design was also obtained for CPRS, whereas the optimal conditions of the pretreatment were 20 minutes pre-hydrothermal treatment and post-oven-acid treatment with 196 H.SO, at the same incubation temperature and time. The highest ethanol yields from optimized pretreatment design for PPR was 75.74 g/L from 48 hours of fermentation and 104.15 g/L after 72 hours of fermentation in CPRS. The energy outputs of the bioethanol
are 0.0083 MJ and 0.0097 MJ respectively and the costs of ethanol liter was 163.93 Baht/L for PPR and 156:32 Baht'L for CPRS. In conclusion, the optimized two-step pretreatment technique developed in this study is a promising method of increasing the overall yield in the bioethanol production process using coconut pulp residue.