Integrated Distillation-Membrane Process for Acetone-Butanol-Ethanol (ABE) Recovery From Surrogate and Actual Fermentation Broth: Separation Energy Efficiency and Fate of Secondary Fermentation Products

A hybrid process integrating vapor stripping with vapor compression and vapor permeation membrane separation, termed Membrane Assisted Vapor Stripping (MAVS), was evaluated for recovery and dehydration of 1-butanol and mixtures of acetone-butanol-ethanol (ABE) from aqueous solution as an alternative to conventional energy-intensive distillation-based processes. The solvent removal and drying performance of the MAVS system with binary butanol-water mixtures and ABE-water mixtures was benchmarked and compared to performance with an actual bacterial ABE fermentation broth. The fate of secondary fermentation products in the system was assessed.

Simple alcohols, esters, and organic acids, displayed varying degrees of recovery in the vapor stripping based on the relative vapor-liquid partitioning of the compounds. All volatilized organic compounds were concentrated to the same degree in the vapor permeation membrane step. Butanol-water molar permselectivity ranged from 60 to 170, depending on the flow rate in the module. Membrane permeance, permselectivity, and overall energy usage of the hybrid process were the same with the fermentation broth as with the binary alcohol-water solutions, indicating no adverse effect of secondary fermentation products on membrane performance. As we have documented with ethanol-water separations[1-2], the MAVS system required significantly less energy than a simple distillation system for ABE-water separation.

 References:

[1]       L.M. Vane, F.R. Alvarez, L. Rosenblum, and S. Govindaswamy, “Efficient ethanol recovery from yeast fermentation broth with integrated distillation-membrane process,” Industrial & Engineering Chemistry Research, DOI: 10.1021/ie2024917.

[2]       L.M. Vane, F.R. Alvarez, Y. Huang, and R.W. Baker, “Experimental validation of hybrid distillation-vapor permeation process for energy efficient ethanol-water separation”, Journal of Chemical Technology & Biotechnology, 85, 502-511 (2010).

*This is an abstract of a proposed presentation and does not necessarily reflect U.S. EPA policy.

This work was part of a Cooperative Research and Development Agreement (CRADA) between the U.S. EPA and Membrane Technology and Research, Inc.