49    ANAEROBIC TREATMENT OF FOOD ADDITIVE
WASTEWATER IN A FLUIDIZED-BED REACTOR
Kenneth F. Potochnik, Senior Development Engineer
Air Products and Chemicals, Inc.
Allentown, PA 18195-1501
Mauro Caringi, Environmental/Safety Manager
Nestle Foods Corporation
Purchase, NY 10577
Ralph Sgammato, Manager of Engineering
FIDCO, Inc.
New Milford, CT 06776
INTRODUCTION
FIDCO, Inc., a subsidiary of Nestle Foods Corporation, operates a manufacturing plant and is host
to a research laboratory in New Milford, Connecticut. The manufacturing plant produces a variety of
food products and additives. The bulk of the manufacturing activities involve batch processes which
generate a process wastewater stream highly variable in both flow and concentration. Operation of
the research laboratory on an eight hour per day basis and the nature of the laboratory activities,
contribute further to the variability of the combined (manufacturing plant plus research lab) wastewater stream. The waste stream is currently treated in an aerobic biological treatment system owned
and operated by FIDCO.
Although the existing aerobic system is capable of meeting the current effluent regulatory requirements, anticipated future increases in production and more stringent effluent quality requirements
will necessitate an increase in treatment capacity and performance. Ammonia removal is of particular
concern. The influent ammonia concentration is high and the existing treatment facility lacks the
aeration capacity for both carbonaceous BOD removal and nitrification.
The normally high concentration of biodegradable organic compounds in the combined wastewater
stream favors the use of an anaerobic biological process as a pretreatment step prior to aerobic
treatment. Installation of an anaerobic pretreatment step would reduce the influent load on the
aerobic system making existing aeration capacity available for nitrification. Anaerobic pretreatment
would also reduce the total waste sludge production at the treatment plant.
A fixed-film biological fluidized-bed reactor was evaluated for the anaerobic pretreatment of the
New Milford plant and research laboratory wastewaters. The fluidized-bed process involves passing
wastewater upward through a bed of media, such as sand, at a velocity sufficient to expand and
fluidize the media. Once fluidized, the media provides a very large surface area for biological growth,
in part leading to the development of reactor biomass concentrations five to ten times greater than
those achieved in suspended growth anaerobic systems. This high biomass concentration makes
possible the use of smaller reactors than those required for suspended growth processes or other fixed-
film processes. Also, the high biomass concentration enhances the ability of the fluidized-bed to
handle inhibitory feed components and variations in organic load.1,2,3
Fluidized-bed systems also have the capacity to handle wide variations in hydraulic loading. The
majority of the flow required to fluidize the support media is provided by recirculated effluent;
therefore, even large changes in the wastewater flowrate will not upset the system. The flowrate
through the fluidized bed remains constant. The high recycle flowrate required for fluidization also
reduces the variability of the wastewater composition.
A pilot test of the fluidized-bed system was conducted at FIDCO between January and May of
1989. The principal objectives of the study were to assess the feasibility of anaerobic fluidized-bed
treatment of a highly variable food additive wastewater and to obtain information for process design
45th Purdue Industrial Waste Conference Proceedings, © 1991 Lewis Publishers, Inc., Chelsea, Michigan 48118.
Primed in U.S.A.
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