title: Ethanol production in a membrane bioreactor: pilot-scale trials in a corn wet mill.
abstract: Pilot plant trials were conducted in a corn wet mill with a 7000-L membrane recycle bioreactor (MRB) that integrated ceramic microfiltration membranes in a semi-closed loop configuration with a stirred-tank reactor. Residence times of 7.5-10 h with ethanol outputs of 10-11.5% (v/v) were obtained when the cell concentration was 60-100 g/L dry wt of yeast, equivalent to about 10(9)-10(10) cells/mL. The performance of the membrane was dependent on the startup mode and pressure management techniques. A steady flux of 70 L/(m2 x h) could be maintained for several days before cleaning was necessary. The benefits of the MRB include better productivity; a clear product stream containing no particulates or yeast cells, which should improve subsequent stripping and distillation operations; and substantially reduced stillage handling. The capital cost of the MRB is $21-$34/(m3 x yr) ($0.08-$0.13/[gal x yr]) of ethanol capacity. Operating cost, including depreciation, energy, membrane replacement, maintenance, labor, and cleaning, is $4.5-9/m3 ($0.017-$0.034/gal) of ethanol.
authors.affiliation: Universidad de los Andes, Departamento de Ingenieria Quimica, Bogotá, Colombia.
authors.forename: J M
authors.initials: JM
authors.lastname: Escobar
authors.forename: K D
authors.initials: KD
authors.lastname: Rane
authors.forename: M
authors.initials: M
authors.lastname: Cheryan
mesh_terms: D019149:Bioreactors / Q000191:economics; D015169:Colony Count, Microbial; D003365:Costs and Cost Analysis; D000431:Ethanol / Q000191:economics / Q000378:metabolism*; D005285:Fermentation; D005742:Gasoline; D008567:Membranes, Artificial; D010865:Pilot Projects; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D003313:Zea mays
chemical_list: D005742:Gasoline; D008567:Membranes, Artificial; D000431:Ethanol