Journal of Biotechnology & Biomaterials
Open Access

Abstract

Sugar is one of the main agricultural industries in South Africa and livelihoods of approximately one million South Africans are indirectly dependent on sugar industry which is economically struggling with some problems and should re-invent in order to ensure a long-term sustainability. Second generation biorefinery is defined as a process to use waste fibrous for the production of biofuel, chemicals animal food and electricity. Bioethanol is by far the most widely used biofuel for transportation worldwide and many challenges in front of bioethanol production were solved. Biorefinery annexed to the existing sugar mill for production of bioethanol and electricity is proposed to sugar industry and is addressed in this study. Since flow sheet development is the key element of the bioethanol process, in this work, a biorefinery (bioethanol and electricity production) annexed to a typical South African sugar mill considering 65 ton/hour dry sugarcane bagasse and tops/trash as feedstock was simulated. Aspen PlusTM V8.6 was applied as simulator and realistic simulation development approach was followed to reflect the practical behavior of the plant. Latest results of other researches considering pretreatment, hydrolysis, fermentation, enzyme production, bioethanol production and other supplementary units such as evaporation, water treatment, boiler and steam/electricity generation units were adopted to establish a comprehensive biorefinery simulation. Steam explosion with SO2 was selected for pretreatment due to minimum inhibitor production. For enzymatic hydrolysis and fermentation of cellulose two different routes as simultaneous saccharification-fermentation (SSF) and separate hydrolysis-fermentation (SHF) configurations were simulated. Bioethanol purification was simulated through two distillation columns with side stream and fuel grade bioethanol (99.5%) was achieved using molecular sieve in order to minimize the capital and operating costs. Also boiler and steam/power generation were completed using industrial design data. Results indicate that 256.6 and 205 kg bioethanol per ton of Dry Mass (DM) feedstock are achieved using SSF and SHF processes, respectively. Results of utility demand indicate that heating and cooling requirements for SSF are 3.5 and 3.38 GJ/ton per ton of feedstock, respectively versus 4.2 and 2.7 for SHF. In terms of ethanol production and energy requirement, SSF process is more attractive for biorefinery annexed to typical South African sugar mill. Further study will be conducted to consider economic parameters as well as environmental effect.

Biography

Email: mandegari@sun.ac.za