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Process for manufacturing ethanol and for recovering glycerol, succinic acid, lactic acid, betaine, potassium sulfate, and free flowing distiller's dry grain and solubles or a solid fertilizer therefrom
This invention relates to the manufacture of ethanol and the recovery of economically significant amounts of such by-products therefrom as glycerol, betaine, L-pyroglutamic acid, succinic acid(cas:110-15-6) and lactic acid, potassium sulfate and a free flowing distiller's dry grain and solubles useful as an animal feed or a component of food for humans or as a premix for agricultural fertilizer and/or a feed additive. An important aspect of the recovery step is the utilization of a crossflow microfiltration system which includes inorganic membranes for the classification of the stillage in succinic acid(cas:110-15-6).
EXAMPLE 1
A mash prepared of ground whole corn was subjected to jet cooking for two minutes at 149° C. and then to liquefaction at a pH of 6.3 to a dextrose equivalent (DE) of 20.3, and to saccharification to DE 36 at pH 4.5. Immobilized yeast cells were prepared by mixing a 1.5 weight percent sodium alginate solution with the preferred ratio of hydrated yeast cells and sterilized sand. The resulting slurry was poured through a 12 mesh screen into an aqueous solution of 0.5M CaCl2 and 1.5 weight percent glucose at pH 4.6 and ambient temperature. On contact with the calcium chloride, the drops formed beads which, after 24 hours in a refrigerator at 4° Celsius, gelatinized into firm beads with diameters of 2-4 mm. The mash was then fermented in two batches at 34° Celsius with free and immobilized yeast cells at concentrations of 5.0 grams per liter. Fermentation was performed in a batch process with no recycling of stillage and adjustment of pH to 5.0 using NaOH. Comparing the two batches, yields were as follows:
EXAMPLE 2
Stillage from a facility for the production of ethanol from wet milled corn was centrifuged and the thin stillage subjected to microfiltration in a ceramic membrane unit. The clear permeate was partially softened and then concentrated through evaporation to 73 weight percent solids, while it still behaved like a Newtonian fluid. It was fed at about 60 percent solids to an IWT Adsep system consisting of a single three inch I.D. column with a bed height of 62.25 inches of IWT SM-51-Na resin. The concentrate was fed at a rate of 2 GPM/square foot, with 20% feed pulse at 1.442 liters/pulse. The glycerol containing effluent was passed through an IWT mixed bed ion exchange unit to improve purity; then adjusted to pH 7.0 using NaOH; then, using Mazzoni equipment, concentrated by evaporation to 83.1 weight percent glycerol; and distilled and refined to a CP/USP grade glycerol of high quality. Constituents in the material at stages in the process were as summarized in the following table showing weight distributions.
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