79    CHARACTERIZATION AND TREATMENT OF WASTES
FROM BLUE CRAB PROCESSING FACILITIES
Timothy D. Harrison, Graduate Research Assistant
Department of Civil Engineering
Gregory D. Boardman, Associate Professor
Department of Civil Engineering
George J. Flick, Professor
Department of Food Science and Technology
Virginia Polytechnic Institute and State University
Blacksburg, Virginia 24061
INTRODUCTION AND OBJECTIVES
In the 1970s, the United States Environmental Protection Agency (EPA) developed documents
which defined effluent limits for segments of the seafood processing industry.' The regulations were
then adopted by the states. Compliance with these limits was obtained, in most cases, with minor
plant modifications that did not require large capital investments and operating costs. During the last
decade, citizen and environmental groups have encouraged more stringent legislation in an effort to
achieve a cleaner environment. Individual states have established waste disposal standards that exceed
current U.S. EPA requirements.
The restoration of water quality in the Chesapeake Bay has become a goal of states which border
the Bay and its tributaries. In Virginia, the State Water Control Board (SWCB) has initiated a
vigorous program to remove pollutants from the Bay. As a result, new standards for the disposal of
liquid and solid wastes have been established. Many blue crab processors have reported serious waste
disposal problems as they are unable to consistently comply with their current allowable pollutant
discharge limits.
The objective of this project was to characterize process effluents, identify ways to reduce waste
quantities and strengths, and determine viable effluent treatment methods at three blue crab processing facilities.
MATERIALS AND METHODS
Plant Processes
The waste streams of each individual process in three blue crab processing plants were characterized. Characterization of effluents from conventional blue crab processes can be found in the literature,2-6 but few data are found on mechanized processes. For the purposes of this paper, the processing facilities will be designated plant #1, #2 and #3, respectively. Two trips were made to plants #1 and
#3. Three trips were made to plant #2.
The typical steps for processing live blue crabs and the wastes generated by each process are shown
in Figure 1. The unrefrigerated live crabs are usually delivered by boat or truck to processing plants.
The crabs are weighed, washed (optional), and then dumped into large stainless steel baskets where
they are placed into horizontal or vertical retorts, and cooked by steaming for 7 to 23 minutes at
121 °C and 15 psig. Approximately 1,000 to 1,800 pounds of live crab are cooked in each retort. The
crabs are then moved to a room where they are air-cooled to ambient temperatures within thirty
minutes and then moved to a cooler (33°F to 40°F) until picking.
If the crabs are to be hand processed, each picker backs, declaws, and removes all meat from each
crab. Picking meat from the crab is labor intensive and is sometimes supplemented in a few large
plants by mechanized picking. The Harris Claw machine combines hammer mills with brine-tank
flotation to remove the meat from claws. The Quik-Pik machine uses high speed vibration to remove
body meat from the crab. The Quik-Pik process may also include a bobber which mechanically cuts
47th Purdue Industrial Waste Conference Proceedings, 1992 Lewis Publishers, Inc., Chelsea, Michigan 48118.
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