No abstract

Background2,3-Butanediol (2,3-BDO) is a synthetic chemical compound that also can be produced by biomass fermentation, which is gaining share in the global market as an intermediate product for numerous applications, i.e. as liquid fuel or fuel additive. Several metabolic engineering fermentation strategies to enhance the production of 2,3-BDO were developed. However, the recovery of 2,3-BDO from its fermentation broth remains a challenge due to its low concentration and its solubility in water and other components. Thus, a cost-effective recovery process is required to deliver the required purity of 2,3-BDO. This paper presents a new process development and techno-economic analysis for 2,3-BDO purification from a fermentation broth.ResultsConventional distillation and hybrid extraction-distillation (HED) processes are proposed in this study with detailed optimization and economic analysis. Particularly, a systematic solvent selection method was successfully implemented to determine a good solvent for the proposed HED configuration based on numerous experimental data obtained with each solvent candidate. NRTL and UNIQUAC property methods were evaluated to obtain binary interaction parameters of 2,3-BDO through rigorous Aspen Plus regression and validated using experimental data. Total annual cost (TAC)-based optimization was performed for each proposed configuration. Even though the HED configuration required 9.5% higher capital cost than conventional distillation, placing an extraction column before the distillation column was effective in removing water from the fermentation broth and significantly improved the overall process economics.ConclusionsOleyl alcohol was found to be the most suitable solvent for the HED of 2,3-BDO due to its high distribution coefficient and high selectivity. The proposed HED drastically reduced reboiler duty consumption and TAC by up to 54.8 and 25.8%, respectively. The proposed design is expected to be used for the commercial scale of 2,3-BDO production from fermentation process.Electronic supplementary materialThe online version of this article (10.1186/s13068-018-1013-3) contains supplementary material, which is available to authorized users.

51Outbreaks of emerging coronaviruses in the past two decades and the current pandemic 52 of a novel coronavirus (SARS-CoV-2) that emerged in China highlight the importance of this 53 viral family as a zoonotic public health threat. To gain a better understanding of coronavirus 54 presence and diversity in wildlife at wildlife-human interfaces in three southern provinces in Viet 55Nam 2013-2014, we used consensus Polymerase Chain Reactions to detect coronavirus 56 sequences. In comparison to previous studies, we observed high proportions of positive samples 57 among field rats (34.0%, 239/702) destined for human consumption and insectivorous bats in 58 guano farms (74.8%, 234/313) adjacent to human dwellings. Most notably among field rats, the 59 odds of coronavirus RNA detection significantly increased along the supply chain from field rats 60 sold by traders (reference group; 20.7% positivity, 39/188) by a factor of 2.2 for field rats sold in 61 large markets (32.0%, 116/363) and 10.0 for field rats sold and served in restaurants (55.6%, 62 84/151). Coronaviruses were detected in the majority of wildlife farms (60.7%, 17/28) and in the 63 Malayan porcupines (6.0%, 20/331) and bamboo rats (6.3%, 6/96) that are farmed. We identified 64 six known coronaviruses in bats and rodents, clustered in three Coronaviridae genera, including 65 the Alpha-, Beta-, and Gammacoronaviruses. Our analysis also suggested either mixing of 66 animal excreta in the environment or interspecies transmission of coronaviruses, as both bat and 67 avian coronaviruses were detected in rodent feces in the trade. The mixing of multiple 68 coronaviruses, and their apparent amplification along the wildlife supply chain into restaurants, 69 suggests maximal risk for end consumers and likely underpins the mechanisms of zoonotic 70 spillover to people. 71 72

Outbreaks of emerging coronaviruses in the past two decades and the current pandemic of a novel coronavirus (SARS-CoV-2) that emerged in China highlight the importance of this viral family as a zoonotic public health threat. To gain a better understanding of coronavirus presence and diversity in wildlife at wildlife-human interfaces in three southern provinces in Viet Nam 2013-2014, we used consensus Polymerase Chain Reactions to detect coronavirus sequences. In comparison to previous studies, we observed high proportions of positive samples among field rats (34.0%, 239/702) destined for human consumption and insectivorous bats in guano farms (74.8%, 234/313) adjacent to human dwellings. Most notably among field rats, the odds of coronavirus RNA detection significantly increased along the supply chain from field rats sold by traders (reference group; 20.7% positivity, 39/188) by a factor of 2.2 for field rats sold in large markets (32.0%, 116/363) and 10.0 for field rats sold and served in restaurants (55.6%, 84/151). Coronaviruses were also detected in rodents on the majority of wildlife farms sampled (60.7%, 17/28). These coronaviruses were found in the Malayan porcupines (6.0%, 20/331) and bamboo rats (6.3%, 6/96) that are raised on wildlife farms for human consumption as food. We identified six known coronaviruses in

A natural gas liquefaction and liquid recovery sequence is proposed for top-side offshore floating liquefied natural gas processing. During liquefaction, a single mixed refrigerant is separated into heavy and light key components, separately compressed after the main cryogenic heat exchanger and then mixed again to make a single mixed refrigerant. The proposed liquefaction cycle has a simple, compact structure and is suitable for power-efficient, offshore, floating liquefied natural gas liquefaction. The natural gas liquid recovery process employs space-and energy-efficient dividing wall columns for the integration of depropanization and debutanization. The columns were optimized by response surface methodology. A compact top dividing wall column configuration could reduce total annual costs. A combined process integrating natural gas liquefaction and liquid recovery is finally proposed.

No abstract

A hybrid purification process combining extraction and distillation for the production of levulinic acid (LA), furfural, and formic acid (FA) from lignocellulosic biomass was studied. The effective process depends on the choice of appropriate extraction solvent. A comprehensive procedure of solvent selection for the LA production process was developed. A range of solvents were first evaluated by solvent screening, and processes using the three most promising solvents, including methyl isobutyl ketone (MIBK); furfural and octanol were then designed and optimized using an Aspen Plus simulator. These processes were evaluated in terms of the energy consumption, total annual cost, and environmental impact. As a result, MIBK showed the most favorable equilibrium for the extraction of LA but was unfavorable for FA extraction. Octanol showed not only the most favorable result in the extraction of FA, but was also favorable for the extraction of furfural and LA. Interestingly, furfural could extract more LA than octanol and extract more FA than MIBK. The design results show that the furfural solvent process can reduce energy consumption by up to 25.2% and 21.4%, the TAC by up to 30.6% and 25.9%, and CO 2 emissions by up to 27.0% and 25.5% compared to processes using octanol and MIBK as solvents, respectively.

No abstract