56    DEVELOPMENT OF A NEW FLUIDIZED BED
ANAEROBIC PROCESS
Jelte Lanting, Technology Manager
Biothane Corporation
Camden, New Jersey 08104
Rob J. Frankin, Sales and Marketing Manager
Biothane Systems International
Delft, The Netherlands
INTRODUCTION
During the past two decades the application of fluidized bed technology for the anaerobic treatment
of wastewater has been studied extensively on laboratory and pilot scale.1,2 On a commercial scale the
application of fluidized bed technology has met with limited success. This may in part be due to the
practical problem of controlling biofilms on the carrier material.
The upflow anaerobic sludge blanket (UASB) technology relies on a combination of "spontaneous"
granulation of biomass and a 3-phase separator in the upper portion of the reactor vessel to retain
adequate biomass in the treatment system. Commercially this technology has been widely accepted
and utilized by industry for (pre)treatment of a variety of effluents. According to our estimates there
are more than 250 UASB installations from various suppliers operating throughout the world.
This paper will describe the operating experiences with a new upflow fluidized bed technology that
blends together attractive features of the fluid bed and upflow anaerobic sludge blanket processes. A
brief overview is given of events that provided the impetus to pursue development of this new
technology, followed by a discussion of four process applications.
BACKGROUND
In the mid 1970s Gist-brocades, a large Dutch biotechnology firm, initiated a program to reduce
discharges and clean up effluents from its yeast production and pharmaceuticals plant in the Netherlands. This program progressed through various stages with initial emphasis on source reduction,
reuse and recycling of (residual) products, and increasing the value and marketability of residuals and
by-products. Toward the conclusion of the waste minimization efforts, a research program was begun
to develop a suitable (pre)treatment system for the remaining effluent.
Largely because of space considerations it was decided to pursue development of a fluidized bed
process for the treatment of the industrial effluent. The results of this development work have been
described in the literature.3'4
The development work had shown that biofilm growth, attachment and stability was not a problem. The following factors were cited:5
• a carrier particle with a diameter of less than 0.5 mm is desirable for good biofilm
attachment;
• a short hydraulic retention time promotes biomass growth in a completely attached mode;
• a two stage configuration promotes biofilm stability;
• biogas production causes sufficient turbulence and shear to balance biofilm growth, thus
ensuring a constant biofilm thickness.
Since pilot plants had been operated in a stable condition for well over a year, special biofilm
control procedures were not contemplated for the full scale plant.
During 1984, Gist-brocades installed full scale two stage fluidized bed digesters at its yeast and
pharmaceutical plants in the Netherlands and France. During 1985 a second two stage unit was built
adjacent to the first one in the Netherlands. Start up and operating data from these facilities can be
found in the literature.5,6
48th Purdue Industrial Waste Conference Proceedings, 1993 Lewis Publishers, Chelsea, Michigan 48118. Printed in
U.S.A.
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