DAIRY WASTE TREATMENT USING INDUSTRIAL-SCALE
FIXED-FILM AND UPFLOW SLUDGE BED ANAEROBIC DIGESTERS:
DESIGN AND START-UP EXPERIENCE
Rejean Samson, Research Officer
Bert Van den Berg, Head, Biological Group
Division of Biological Science
National Research Council of Canada
Ottawa, Ontario
Canada K1A OR6
Roeland Peters, Project and Development Director
Claude Hade, Environmental Technologist
Agropur, Cooperative Agro-Alimentaire
Granby, Quebec
Canada J2G 7G2
INTRODUCTION
Increasingly stringent environmental regulations coupled with rapidly rising energy costs make
anaerobic digestion the preferred process for the treatment of soluble dilute waste [1]. Treatment of
dairy waste using advanced anaerobic digesters has been successfully used at laboratory scale. Reactors studied included the upflow sludge bed and contact process reactors [2,3,4] and the fixed-film
reactor from Canada [5]. All these new technologies have in common the capacity to work at a high
loading rate and high removal efficiencies because they have the ability to retain high concentrations
of active biomass. Loading rates of 7 to 30 kg COD/m3/d and COD removal efficiencies of 60 lo 97%
have been reported. Also, methane production rates as high as 5 m3 (STP)/m3/d were possible.
This paper deals with the technical or economical feasability of using these reactors for the treatment of cheese factor dilute effluent and methane production on an industrial scale. The discussion
focuses on the design and utilization by Agropur of two types of individual scale advanced anaerobic
digesters, the downflow stationary fixed-film (DSFF) reactor and the upflow sludge bed (USB) reactor
(400 m3 each). These reactors form the major piece of a complete wastewater treatment facility for the
treatment of wastewater from a cheese factory in Notre-Dame-Du-Bon-Conseil, Quebec, Canada. A
description of the complete wastewater treatment plant, and results obtained during the first year of
operation are presented.
DESCRIPTION OF THE AGROPUR'S CHEESE FACTORY
Agropur is a progressive food processing co-op involved in the manufacture and distribution of
dairy products. It processes about 20% of the milk produced in Canada. The Notre-Dame-Du-Bon-
Conseil plant located near the Nicolet River processes about 1 million kg of milk per day for the production of cheddar cheese and milk powder. Cheese is made during 5 days of each week but milk
deliveries, pasteurization and milk powder making occur 7 days per week. The main source of wastewater generation is the clean-up operations which consist of the cleaning of tank trucks, transport
lines and equipment whenever a production run comes to a halt. Other sources of wastewater generation are related to equipment malfunctions or operation errors which can cause dumping of whole
milk and cheese whey. The composition of the plant effluent varies hourly (Table I) and also depends
on the cleaning cycle. The average COD concentration was around 2 800 mg/l while the sodium content of around 500 mg/l indicates the amounts of NaOH used in the equipment clean-up operations.
Because the space loading of the reactors is designed for an influent of about 3000 mg COD/1, overloading sometimes occurs when milk or whey spills increase the COD concentration up to 10,000 mg
COD/I with a large fraction due to long chain fatty acids.
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