Recently completed research funded by the U.S. Poultry & Egg Association profiled
processing plant wastewater discharges. The study is part of the association’s
extensive industry research program encompassing all segments of broiler, turkey,
and commercial egg operations. More than $3 million is currently invested in ongoing
A brief overview of the completed research is shown below. Additional information
may be obtained from the authors on the date and place of publication of the data
generated by this research project.
Profile and Production Process Determination of Phosphorus and Nitrogen Wastewater
Discharges from Poultry Processing Plants
William C. Merka, Ph.D.
Poultry Science Department / A. Estes Reynolds, Ph.D. Food Science and Technology
Jackie Sellers, Ph.D. / Brian Kiepper - Biological and Agricultural Engineering
Department - The University of Georgia - Athens, GA 30602
Profiling Processing Plant Wastewater Discharges
The discharge of excessive nitrogen and phosphorus from agricultural and industrial
sources into U.S. waters is a major environmental concern (Tusseau-Vuillemin,
2001; Sharpley, 2000; Gaskin and Harris, 1999). As a result, the poultry industry
in the United States has become a leader in the fight to control the discharge
of excess nutrients into ground and surface waters by implementing proactive management
practices in both its production and processing sectors.
To meet established environmental regulations, the poultry industry has been extremely
thorough in the tracking of nitrogen and phosphorus discharges in final wastewater
effluents from processing plants (Carawan, 1989; Westerman et. al., 1989). To
increase the processing industry’s ability to control nutrient discharges
under increasingly restrictive limits, research is needed to identify the work
shifts and processing steps that contribute the highest percentage of nutrient
loading to wastewater streams.
The major objective of this research project was to establish the specific times
and processing operations that contribute the highest loading of nitrogen and
phosphorus to wastewater streams, thus identifying target areas for reducing future
discharges. In addition, the project had the objective of identifying similar
trends of nutrient discharges for facilities with analogous operations.
To accomplish these objectives, the research team collected 24-hour representative
samples of process wastewater from three different processing locations and from
the effluent of wastewater treatment screens at six poultry processing facilities.
Sampling was conducted for a minimum period of three consecutive days at each
Three slaughter plants and three further processing plants were selected for the
project. Additional operations at one or more of the slaughter plants include
cut-up, deboning, and marination. The three further processing plants were all
unique in their operations: one ‘cook’ plant, one portion control/par-fry
plant, and one marination/grinding/extrusion plant were profiled.
Each plant had four specific sampling sites where 24 hourly discrete samples were
collected daily and then pooled based on individual plant production and sanitation
shift schedules. Each representative sample was then analyzed for Total Kjeldahl
Nitrogen (TKN) and Phosphorus (P). By combining the resulting concentration data
with observed, recorded, and estimate wastewater flows, a pounds of nutrient loading
value for each sample was calculated and graphed based on work shifts.
Project results show that nutrient discharges in the screened wastewater of the
three slaughter plants follow consistent trends and that accurate models can be
developed to predict nitrogen and phosphorus discharge rates with a minimum of
input data. Results also show that periodic calculation of nutrients discharges
can be an efficient tool for monitoring in a waste minimization program. In addition,
we found that effective dry clean-up measures in live haul areas could reduce
nutrient loading to the wastewater streams of slaughter plants by 5-10 percent.
Further processing plant nutrient discharge findings show that individual pieces
of equipment and specific plant operations can be effectively isolated to focus
nutrient discharge reduction efforts.
Finally, project findings highlight the importance of calculating accurate loading
of nutrients to waste streams to determine areas of highest impact. Reliance on
concentration data alone can mislead and impede efforts in making effective nutrient
Overall, the project underscores the benefits of accurate nutrient discharge monitoring
in establishing proactive programs geared at meeting current and future environmental
benchmarks in the reduction of nitrogen and phosphorus discharges from poultry