ANAEROBIC PRETREATMENT OF BREWERY WASTEWATER
ON THE INDUSTRIAL SCALE
Robert I. Sax, Director
Biothane Corporation
Camden, New Jersey 08104
INTRODUCTION
In order to relieve loading to the LaCrosse, Wisconsin municipal treatment plant, the G. Heileman
Brewing Company, henceforth in this paper for convenience referred to as GHB, was required in
the late 70's to institute measures to pretreat their brewery effluent. After examining various alternative forms of biological treatment, it was decided by the GHB staff that anaerobic digestion technology offered the most economical and most space-efficient possibility for solving the problem. A
consulting engineering firm was hired to investigate the different anaerobic processes commercially
available, and, early in the year 1980, a decision was reached to pilot test an Upflow Anaerobic Sludge
Blanket (UASB) process originally developed in Holland by the group under Professor Lettinga at
the Agricultural University of Wageningen, and later brought to commercial application by the beet
sugar firm, CSM. This process, which subsequently has become known throughout the world as
"Biothane," was successfully pilot tested at GHB using a digester vessel of volume capacity 6 m' to
treat daily COD loads of approximately 60 Kg. Based on these results, GHB entered into a contract
for construction of a full-scale Biothane system late in 1980. The process was brought on-line at GHB
a year later, and, by mid-summer of 1982, was accepting nearly all of the available effluent from
the brewery. Except for short down times to enable execution of certain modifications to the physical
plant, the process has been operated continuously since that time. This paper will examine the performance of the Biothane system at GHB and will discuss the modifications which were made to the
plant and the rationale for making such modifications.
PROCESS DESCRIPTION
The operating principle of the Biothane process is demonstrated schematically in the cutaway
view of a digester shown in Figure 1. Wastewater enters the bottom of the digester vessel through
regularly spaced inlet ports and passes upwards through the dense bed of anaerobic biomass. Soluble
COD is very rapidly converted to a biogas rich in methane content, and an upward circulation of
water and gasborne sludge is established. The specially constructed separator topworks (settler sections) in place at the top of the digester vessel allow effective degasification of the biomass to occur.
The dense, granular sludge particles, now devoid of attached gas bubbles, sink rapidly back towards
the bottom, thereby establishing a return downwards circulation. The treated effluent flows upwards
through the settlers and over weirs at the top into collection channels for discharge while the directly
combustible biogas is recovered from collection pockets underneath the baffles. The upward flow of
gasborne sludge in combination with the return downward flow of degassed sludge creates continuous
convection within the digester and insures effective biomass-waste contact without the need for any
energy-consuming mechanical or hydraulic agitation. The unique design of the digester allows a high
active biomass concentration in relation to soluble organic solids passing through the bed and is
responsible for the very high loading rates, and consequently extremely short hydraulic retention
times which can be achieved routinely with this process.
The difference between the UASB process and other types of anaerobic technologies is the concept
of retention of biomass within the digester by means of internal settling. The difference between the
Biothane process and other types of UASB technologies is the mechanical design and construction
of the internal degasification settler baffle arrangement. The patented Biothane settler design optimizes efficient degassing of the biomass to insure minimal carryover and promote development of
a granular biomass with excellent settling characteristics. A concentration density of 10% solids or
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