Laboratory Studies into the Reduction of Pollution
From Poultry Processing by In-Plant Recycle
LESTER S. BERRY, Graduate Student
PATRICK F. LAFAYETTE, Graduate Student
STANLEY W. REED, Graduate Student
FRANKLIN E. WOODARD, Associate Professor
Civil Engineering Department
University of Maine
Orono, Maine 04473
INTRODUCTION
As the wastewater discharge limits imposed on polluting industries become more
stringent, manufacturers must find new technology and process modifications to allow
them to continue operation. The poultry processing industry is an example. Faced with the
problem of continually upgrading the quality of its discharged wastewater, it must develop
new concepts for wastewater treatment or in-plant water use.
The proposed discharge limitations under the NPDES permit system for poultry
processing plants are 0.40 pounds of BOD5 per 1,000 pounds of broilers processed and 0.62
pounds of suspended solids per 1,000 pounds of broilers processed. Slightly higher
allowances are made for the processing of heavier birds, referred to as foul, amounting to
0.46 pounds of BOD5 and 0.62 pounds of suspended solids per 1,000 pounds of birds
processed.
These limitations amount to more than 98 percent removal of BOD. suspended solids
and oil and grease for most poultry processing plants (I, 2, 3, 4). They were based on the
performance of a wastewater treatment system in Florida which incorporated high detention time aerated lagoons and a polishing pond (4). This type of system is not a viable alternative for plants which have limited land area available to them or are located in a colder
climate. The only means by which these plants can meet the proposed limitations are by the
use of tertiary treatment, by conversion to "dry" processing methods, or by the in-plant
recycle of water.
The work reported on in this paper is the first phase of an on-going project directed
toward determining the feasibility of in-plant wastewater treatment and recycle. The basic
questions addressed are: Can poultry processing wastewater be treated sufficiently to allow
its safe reuse? Is the treatment and reuse concept economically feasible? How does the cost
of treatment and reuse of individual unit processing wastewaters compare to the cost of
tertiary treatment of the combined plant wastewater flow?
The approach taken to develop answers.to these questions was to study the treatability
of both the total combined wastewater flow from a poultry processing operation as well as
waste flows from certain individual unit processes within the plant. The treatment methods
studied were of the physico-chemical type.
Figure 1 presents a schematic of a typical poultry processing plant. Live birds are
received, killed, bled, then immersed in a hot water bath called a scalder. They are then
defeathered and washed, then eviscerated. Next, they are cooled in an icewater bath called a
chiller, then packed for shipping or sent to "further processing." There are three major
sources of wastewater; the scalder, the eviscera carriage flume and the chiller. Other
wastewater sources result from feather carriage, bird washing, hand washing and plant
washdown.
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