Effect of acetic acid on biorefinery pretreatment detoxification and fermentation.

摘要

A method for removing acetic acid from pretreated biomass hydrolysate was investigated. This system was characterized by the mass transfer characteristics of the agitated system and subsequent fermentability of the detoxified substrate. Six commercially available activated carbons were evaluated for acetic acid removal in an adsorption isotherm test and the activated carbon Calgon BL was selected for further kinetic testing. Kinetic tests performed at 50, 100, 150, 200, and 250 rpm at both 15°C and 25°C along with an external mass transfer-diffusion model allowed the determination of the effective diffusivity and external mass transfer parameters. The external film coefficient results ranged from 33.62 μm/s to a complete absence of external mass transfer resistance and the diffusivity results ranged from 0.8625 to 10.70 μm 2/s. The optimum combination of no external film resistance, and highest diffusivity, 10.70 μm2/s, occurred at 250 rpm and 25°C.; A qualitative relationship between adsorption and dispersion was also developed using the computational fluid dynamic software package MixSim ®. Mixing times for this four-liter agitated system ranged from 13.65 to 68.27 seconds. These times were small enough to have had little effect on the overall adsorption of acetic acid.; Finally, the residual effects of the carbon treatment process were tested via fermentability studies of both synthetically derived and actual biomass substrates. Biomass concentrations for the treated system initially containing zero, two, and five grams per liter of acetic acid were equal to those found in an untreated sample containing zero grams per liter of acetic acid. The fermented corn stover hydrolysate had biomass concentrations nearly 60 percent higher than its untreated counterpart.; Overall, the activated carbon system of Calgon Carbon BL effectively removed 60 percent of the acetic acid from a hydrolysate solution in a manner not detrimental to the fermentability of the substrate and in 1/24 th of the time stated by the manufacturer.