Integrated process for producing “clean beef” (or milk), ethanol, cattle feed and bio-gas/bio-fertilizer
An ethanol unit and anaerobic digestion/bio-fertilizer unit are integrated with a cattle feedlot (or dairy operation), wherein a continuous, balanced process yields a sanitary, low- to zero-pollution, and economically efficient production of “clean beef” (or milk), fuel ethanol, and bio-gas/bio-fertilizer. Fossil fuel consumption is substantially reduced, even eliminated, and 100% of the cattle waste is treated in digesters wherein it is converted into medium-BTU gas (bio-gas), organic fertilizer and bio-compost. The ethanol unit serves the purposes of ethanol production, grain pretreatment to produce feed for the cattle and production of a thin stillage which is fed to the digesters. The grain is first processed in the ethanol unit, where the starch portion is converted into ethanol and CO 2 . The remaining portion is separated into the thin stillage and a wet cake which is fed directly to cattle as a superior ruminant animal ration which displaces certain traditional feed components, alters the standard starch to protein ratio, and significantly improves conversion efficiencies and meat/milk quality.
1. An integrated continuous process for the production of ethanol and biogas comprising:
fermenting grain in an aqueous medium to produce ethanol in said medium, a residue, and carbon dioxide;
separating the ethanol and residue;
separating the residue into wet cake and thin stillage;
feeding the wet cake to livestock, said wet grain residue constituting 25-80% of a feed ration of said livestock on a dry weight basis;
collecting manure produced by the livestock;
admixing, at least a portion of the collected manure and at least a portion of the thin stillage to produce an admixture; and
digesting the admixture to produce bio-gas, a liquid effluent and, as a residue, a bio-fertilizer.
2. A process according to claim 1 further comprising:
dry milling the grain fed to said fermenting for producing ethanol utilizing the energy produced by combusting said biogas.
3. A process according to claim 1 further comprising milling the grain prior to fermenting.
4. A process according to claim 1 , wherein said digesting is either plug flow or mechanical mixed digestion.
5. A process according to claim 1 , wherein the wet cake from the ethanol production is fed to the livestock without drying.
6. A process according to claim 1 , wherein said fermenting produces said wet cake in an amount substantially equal to 25-80% of a total feed requirement of said livestock.
7. A process according to claim 1 , wherein:
the amount of stillage in admixture with collected manure is regulated, along with the transfer of waste heat from the ethanol unit, to maintain said digesting at a temperature of at least 99° F.
8. A process according to claim 1 , wherein:
the amount of stillage in admixture with collected manure is regulated, to prevent build-up of ammonia in a digester in which said digesting is effected.
9. An integrated continuous process for the production of ethanol, a biofertilizer, calcium phosphate, and bio-gas comprising:
fermenting grain in an aqueous medium to produce ethanol in said medium, a residue, and carbon dioxide;
separating the ethanol and residue;
separating the residue into wet cake and thin stillage;
feeding the wet cake to livestock, said wet grain residue constituting 25-80% of a feed ration of said livestock on a dry weight basis;
collecting manure produced by the livestock;
admixing at least a portion of the collected manure and at least a portion of the thin stillage to produce an admixture;
digesting the admixture to produce bio-gas, a liquid effluent containing phosphorus, and as a residue, biofertilizer;
separating the liquid effluent from the residue;
adding a calcium compound and at least a portion of the carbon dioxide to the liquid effluent to precipitate at least a portion of the phosphorous as calcium phosphate and obtain a phosphorous depleted liquid; and
separating the calcium phosphate from the phosphorous depleted liquid.
10. A process according to claim 9 , wherein said calcium compound is lime.