A new method for COD and COD peak alarm measurements in beer and soft drink plants

World Class Manufacturing Session
Daniel Gore, Anton Paar, Graz, Austria
Co-author(s): Josef Bloder, Anton Paar, Graz, Austria

ABSTRACT: All breweries and beverage manufacturers, regardless of size, rely on either private or public wastewater treatment centers and must adhere to local, state, and federal laws for effluent quality. Effluent COD (chemical oxygen demand) is not permitted to exceed specific limits, typically between 2,000 and 4,000 mg/L, and it is unfortunately not uncommon for higher level COD effluent to enter the wastewater stream due to equipment failure or human error. This paper explains how a new method for COD monitoring works and demonstrates how expensive fines or costs created by high COD levels can be avoided. Several options are currently available to measure COD, or BOD (biological oxygen demand), but they are relatively costly and rely on time-consuming measurement methods that create a very low measurement frequency. A new method, relying on density and/or sound velocity and conductivity, is used to continuously measure the wastewater stream and determine the COD in real time. Due to the system’s in-line location and continuous measurement, COD spikes are also monitored. As density and sound velocity are already a well-known and established method for measuring sugar and alcohol contents of final products in the beverage industry, they also correlate very well to COD. The reproducibility and accuracy of any COD measurement depend on variations in the composition of the wastewater. The various components found in brewery and beverage wastewater streams, namely the sugars maltose, glucose, and sucrose, as well as alcohol, acids, and alkalis, correlate very well with density and sound velocity and, therefore the COD value as well. Once additional acids and alkalis are added via CIP procedures, however, the density and sound velocity values are no longer reliable and require the addition of conductivity and/or pH to allow accurate measurement of all components. Sugars and alcohol have a very large effect on COD, and very small concentration changes have a huge impact on final COD. For example, an extract/sugar content change of 0.01°P is equivalent to 112 mg/L COD, and an alcohol content change of 0.01% m/m is equivalent to 209 mg/L COD. A total COD of 10,000 mg/L is actually less than 1°P! Depending on the needs of the brewery, a less advanced alarm only system, comprising sound velocity and conductivity, may be sufficient for avoiding large COD spikes. However, by combining density with sound velocity and conductivity, composition fluctuation errors are drastically reduced, and accuracy improves by a factor of five over sound velocity alone. A complete COD monitoring system is able to control more advanced measures such as wastewater release, addition of dilution water or chemicals, and shunt out-of-spec wastewater to a holding tank for further evaluation and blending.

Daniel Gore received his B.A. degree from the University of Maryland, College Park, including two years of study in Germany. After graduating in 1995 he returned to Germany and began an apprenticeship as a brewer and maltster at the Lammbrauerei Hilsenbeck. After successfully finishing his apprenticeship he worked in multiple breweries throughout Germany, including the Uerige Obergärige Hausbrauerei and Quenzer Bräu before moving back to the United States to assume the role of head brewer at the Long Trail Brewing Company. In 2006 he changed focus to work as a technical sales representative for Anton Paar, USA and continued to put his 12 years of practical brewing experience to good use serving the beverage industry. During this time Daniel was a member of MBAA and ISA and enjoyed working with local chapters in the Northeast. In 2010 he moved to Graz, Austria, to become Anton Paar GmbH’s application specialist, supporting Anton Paar’s existing applications in the beverage industry, as well as developing new beverage applications and technologies.