ST1-04: Revolutionary sensor to measure progress of processing lignocellulosic sugars to biofuels and biochemicals

Bioconversion of lignocellulosic biomass to biofuels and biochemicals is a complex process. To become economically viable it will require high conversion yields and operation near optimal conditions (i.e. minimum chemical, microorganisms, and energy usage). Thus, the robust analytical methods that can follow the progress of hydrolysis and fermentation as well as biomass separation are badly needed. The current analytical instrumentations are relatively simple (pH, pO₂, and ethanol concentration) or not generally suitable for commercial operations (HPLC or GC methods are time consuming, expensive and difficult to use in the industrial setting). The objective of this research was to study the progress of biomass to bioproducts conversion by using Raman spectroscopy to measure the concentration of hydrolysis and fermentation substrates (mixture of 5 and 6C sugars from lignocellulosic biomass), products (ethanol, xylitol, etc.), inhibitors and separation products.

In this paper we show that Raman spectroscopy has a great potential to be utilized immediately in the industrial setting to control the progress of biomass hydrolysis, fermentation as well as biomass separation. The new Raman spectroscopy method is cheap (no sample preparation required), rapid (10 seconds per sample), accurate (the carbohydrates and lignin concentration determined by Raman spectroscopy correlates well with determination using HPLC and UV spectroscopy (R²=.999 and R²=.995, respectively), robust (proven to work in the hydrolysis and fermentation media from steam pretreated switchgrass and sugarcane bagasse), continuous and simply to use (Raman probe inside of hydrolysis and fermentation media performing continues readings).