Abstract: A process and system for converting animal waste to useful biofuel products, and more particularly a process and system for converting excrement from lactating dairy cattle to a combination of ethanol, methane, carbon dioxide and fertilizer is presented. The system uses a continuous process to place the animal waste into an aqueous mixture with a starter sugar and a digestive microorganism into a heated anaerobic digester. The products of the reactions within the digester include methane, which is extracted in a gaseous form, and ethanol and carbon dioxide, which are separated out of an aqueous solution in a distillation column. The water from the solution is recycled and the solid residue remaining in the digester is dried in a rotary kiln and granulated to form a fertilizer material.

Abstract: A process and system for converting animal waste to useful biofuel products, and more particularly a process and system for converting excrement from lactating dairy cattle to a combination of ethanol, methane, carbon dioxide and fertilizer is presented. The system uses a continuous process to place the animal waste into an aqueous mixture with a starter sugar and a digestive microorganism into a heated anaerobic digester. The products of the reactions within the digester include methane, which is extracted in a gaseous form, and ethanol and carbon dioxide, which are separated out of an aqueous solution in a distillation column. The water from the solution is recycled and the solid residue remaining in the digester is dried in a rotary kiln and granulated to form a fertilizer material.