35    OPERATING EXPERIENCE WITH A NEW ANAEROBIC
EXPANDED BED WASTEWATER TREATMENT PROCESS
AT A GRAIN PROCESSING PLANT
Jelte Lanting, Technology Manager
Jill A. Jordan, Manager Technical Services
Biothane Corporation
Camden, New Jersey 08104
INTRODUCTION
At the 1993 Purdue Conference a paper ' was presented about a new anaerobic expanded bed
process which combines features of upflow anaerobic sludge blanket and traditional sludge-on-
carrier fluid bed processes. At the time, full-scale operating experience with this new technology,
trademarked Biobed®, was limited to a handful of installations in Europe. Since that time, full-
scale plants have been constructed on three continents, including six in the USA.
The first full-scale Biobed anaerobic pretreatment system in North America began operation in
April of 1994 at a grain processing plant in Illinois. The pretreatment system was installed upstream of an existing aerobic activated sludge process to accommodate the pollutant load increase resulting from an expansion of the production facility.
Two years of operating experience will be reviewed. Wastewater flow and composition projections which were used to develop design criteria for the full-scale pretreatment plant will be discussed. The Biobed system and process will be briefly described, followed by a presentation and
analysis of almost two years' worth of process performance data.
Finally, the chapter will address operating costs in general, and chemical consumption in particular, for the combined anaerobic and aerobic wastewater treatment system. These operating
expenses will be related to the pollutant mass loading being processed by the wastewater treatment plant, thus creating unit cost factors which can be compared to those of other wastewater
treatment processes.
BACKGROUND
Midwest Grain Products of Illinois, Inc. (MWG) produces vital wheat gluten, ethanol products, carbon dioxide, and animal feed. After plant expansion, MWG will also produce premium
wheat starch.
Wheat gluten is extracted from wheat flour by washing. The resultant starch slurry can be either dried, or pumped to the distillery for conversion to ethanol. The wet wheat gluten is dried
and packaged. Starch slurry which is not dried is combined with ground grain and cooked. The
starch is then converted to sugar using enzymes. The resultant mash is fermented with yeast,
converting sugars into ethanol and carbon dioxide.
The fermented mash, or beer, is distilled to remove ethanol from the spent grain. This ethanol
is processed into fuel ethanol by removing all water, or into high quality ethanol for beverage
and industrial uses by removing higher alcohols, esters, and aldehydes.
The spent grains which consist mainly of protein, fat, fiber, and higher carbohydrates are centrifuged. The centrifuge cake is dried in a feed dryer. The centrate is evaporated into a syrup
which is also added to the feed dryer. The resultant feed is an animal feed supplement. COD load
estimates from various production sources before and after plant expansion have been summarized in Table I.
51st Purdue Industrial Waste Conference Proceedings, 1996. Ann Arbor Press, Inc., Chelsea, Michigan 48118.
Printed in U.S.A.