Review of Technological Advances in Bioethanol Recovery and Dehydration

Abstract

Today, at the threshold of the 21st century, rising apprehensions about the instability of oil prices, energy security, and adverse effects of fossil fuels on the environment, have made it imperative to search for alternative energy resources that are clean and sustainable. Among various biofuels, bioethanol is very promising. Bioethanol obtained from the fermentation of biomass is dilute and needs to undergo recovery and dehydration before its use as a fuel. This separation step is one of the energy-intensive steps in bioethanol production, which continues to motivate continual advances in bioethanol separation design. Hence, this review paper focuses on the recent advancements in the development of bioethanol recovery and dehydration processes. It is organized in the form of an annotated bibliography, whereby 54 journal papers and book chapters from the year 2008 to 2016 are summarized based on a classification according to separation technology employed. In addition, quantitative performance indicators (namely, cost and energy required for separation) in the papers/book chapters reviewed are presented on a consistent basis (per unit of bioethanol produced). All these will be useful to researchers and practitioners for technology selection and/or further advances in bioethanol separation.

Second Generation Bioethanol Production: On the Use of Pulp and Paper Industry Wastes as Feedstock

“…However, in many studies using Kraft pulp (Table 3), SSL (Table 4), or PPMS (Table 5), the concentrations of ethanol obtained in the fermentation broth were much lower than the recommended minimum of 4 wt % that is required to have a lower energy demand in the recovery step [93]. The most used method in the recovery of ethanol, distillation, is energy-intensive, accounting for 60−80% of the total separation cost of bioethanol from water, particularly due to low ethanol concentrations in the fermented broth [94]. The ethanol concentrations that were reported so far would significantly increase the recovery costs.…”

“…Distillation is energy-intensive, accounting for 60−80% of total separation cost of bioethanol from water, particularly due to low ethanol concentration in the broth. In order to be blended with gasoline, anhydrous ethanol (>99.5 wt % ethanol) should be obtained and a dehydration step after distillation is required [93,94]. In the past, dehydration was usually achieved by azeotropic distillation [52].…”

Multivariate statistical optimization of the ethanol fuel dehydration process using ionic liquids

“…The optimized results obtained were compared with the literature from an extensive review of recent advances in the development of bioethanol recovery and dehydration processes [50]. Fifty-four publications were identified on the topic.…”

Systematic procedure and framework for synthesis and evaluation of bioethanol production processes from lignocellulosic biomass

“…While Singh and Rangaiah (2017) reviewed and compared different technologies available for ethanol dehydration. Cardona et al (2010) reported an energy consumption of 3.43 kW/kg of ethanol for azeotropic distillation, 4.25 kW/kg of ethanol for pressure swing absorption and 2.70 kW/kg of ethanol for molecular sieves.…”