ANAEROBIC EXPANDED BED TREATMENT OF WHEY
Michael S. Switzenbaum, Assistant Professor
Department of Civil and Environmental Engineering
Clarkson College of Technology
Potsdam, New York 13676
Scott C. Danskin, Environmental Engineer
Airco Carbon
Niagara Falls, New York 14302
Whey, a green-yellow liquid, is a by-product of all cheese production. Each pound of
cheese produced results in five to ten pounds of fluid whey. In the United States, approximately 37x10   pounds of whey are produced each year [ 1 ].
The high organic content of whey leads to a severe disposal problem. The BOD of whey
ranges from 32,000 to 60,000 mg/l [2]. Every 1000 gallons per day of raw whey discharged
into a sewage treatment plant can impose a load equal to that from 1800 people. Thus,
whey is produced in large volumes with a high organic content.
Whey can be thought of as a resource awaiting discovery. It has a high content of lactose
and protein. Over the recent past, several investigations have developed new schemes of
whey treatment with the emphasis on product recovery and new product development.
Among these efforts have been fermentation of whey to ethanol for beverage production
[ 1], or gasohol production [3]; drying of whey into powder which may be used as animal
feed or as a supplement in human foods [4]; separation of whey components by membrane
technology [2]; and fermentation of whey for protein production [5]. Many of these
schemes, however, are limited to larger dairy producers due to economic constraints. At this
point whey is still a significant waste problem necessitating proper treatment.
The types of waste treatment methods used in the dairy food industry are primarily
activated sludge, trickling filter, aerated lagoons, irrigation and a combination of these
processes. Another waste treatment alternative which has only been used sparsely is the anaerobic process. Anaerobic processes were at one time used in the septic tank treatment of
the waste from very small dairies. As these dairies grew, most turned to aeration, then conventional activated sludge units. However, the few reports of anaerobic treatment of dairy
waste have shown that theprocess can obtain good treatment efficiencies using conventional,
contact, and fixed film processes [6-10].
Anaerobic treatment offers several advantages over aerobic processes [11], such as (a)
a higher degree of waste stabilization; (b) a lower microbial yield; (c) a lower nutrient requirement; (d) no oxygen requirement; and (e) methane gas production. With regard to anaerobic treatment of whey, these advantages are pronounced since whey constitutes a high
organic loading which is often deficient in nutrients. In addition, the methane produced,
a high quality automatically separated form of energy, can be used at the cheese production
plant for heating and cooking (i.e. a ready market demand at its source of production). It
represents a significant resource recovery.
Thus anaerobic fermentation offers a dual benefit to cheese manufacturers—energy
production and pollution control. Yet, it is used only sparsely for the treatment of whey.
This most likely is a result of the general feeling of unreliability anaerobic processes receive
due to several limitations commonly associated with the process. Foremost are the temperature requirements of 35 C for efficient treatment and lack of stability following changes in
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