FERMENTATION
cleaning head is matched to the CIP cycle time and that the head is rotating properly. It can be easy to install a new cleaning head and not remember to make the appropriate adjustments, he adds. A rotating head with off timing can result in a significant portion of a tank not being properly cleaned. Decisions to slow throughput could be problematic as well. A simplified example would be to slow the flow in the plant by 50 percent. “What are the implications of this from a hygienic point of view?” he asks. If the turbulence in the pipes and heat exchanges is reduced, particles are less likely to stay in suspension, he suggests, and deposits are more likely to form. Cleaning protocols may need to be adjusted to insure those deposits are flushed out.
contaminant microbes, the industry's only recourse might become cleaning and sanitation of all vessels and ancillary equipment prior to addition of almost sterile mash and the adding of culture yeasts with very few contaminating microbes,” Ingledew says. “This cleaning and sanitation technology is already used in the dairy and brewing industries, but is more expensive and would reduce profits significantly.” Dairies and breweries use things like caustic cleaning solutions, descalants, sodium
hypochlorite, iodophors and hydrogen peroxide to sanitize. “It will take such measures to eliminate the use of antibiotics, yet remove inherent contamination at decent cost,” he adds. “Serious microbial audits in the plant will become commonplace.” Author: Susanne Retka Schill Contributions Editor, Ethanol Producer Magazine 701-738-4922 sretkaschill@bbiinternational.com
What’s an Acceptable Loss?
So, if bacteria are ubiquitous and plant design sometimes works against thorough hygiene, how clean is clean enough? “We have to be realistic, alcohol plants are not pharmaceutical, they are not going to be sterile,” Walker says. “It’s a case of keeping an eye on the process and monitoring potential contaminating microorganisms. It’s going to be impossible to completely, 100 percent, remove them. As long as plant managers are able to live with what might be there, and it is not deleteriously affecting the yields and the process to a huge extent, that’s probably going to be okay.” Mike Ingledew, professor emeritus at the University of Saskatchewan who preceded Walker as the scientific director of The Alcohol School, suggests that even low, 1 to 4 percent losses in well-operated plants adds up to serious money. Running his calculations a year ago, with 209 plants in the U.S. producing 14.76 billion gallons, Ingledew figured a 1 to 4 percent loss amounted to between 147 MMgy to 588 MMgy for the industry as a whole. With ethanol at $2.20 per gallon, that would add up to an average loss per plant ranging between $1.5 million to $6.2 million per year, all at low infection levels. The move towards decreased antibiotic use has increased the chance for infections, Ingledew adds. “In my view, unless someone finds new antimicrobials that act at low concentrations to kill or prevent growth of
SET THE RECORD IN FERMENTATION Now you can accelerate your ethanol fermentation rate by 5% or more with DuPont™ FermaSure® XL. Eliminating hours from your fermentation process allows improved ethanol yield efficiency while eliminating antibiotic concerns in co-products. Finish in record time with FermaSure® XL.
DuPont™ FermaSure XL®
Call 1-800-477-6071 more information or visit FermaSure.dupont.com
copyright © 2012 DuPont. All rights reserved. The DuPont Oval Logo and Dupont™ are trademarks or registered trademarks of E.I. du Pont de Nemours and Company.
JANUARY 2013 | Ethanol Producer Magazine | 43