POULTRY WASTE PRETREATMENT THROUGH DISSOLVED AIR
FLOTATION COUPLED WITH LIME-POLYMER CONDITIONING
Michael H. Zimmerman, Environmental Engineer
Black and Veatch Consulting Engineers
Kansas City, Missouri 64114
Ricardo B. Jacquez, Assistant Professor
Department of Civil Engineering
University of Missouri-Rolla
Rolla, Missouri 65401
The presence of grease and oU (G&O) in the influent waters to a wastewater treatment
facUity is one of the most serious problems affecting facUity efficiency. If domestic and
industrial wastewater having a relatively large industrial fraction of G&O reaches a treatment facUity, the facUity may experience a skimming problem in the primary clarifiers, an
organic overload in the biological units, and clogging of the conveying sewer lines. Pretreatment is required for G&O reduction in the industrial segment to effectively minimize these
problems.
The poultry processing industry has encountered problems associated with direct disposal
into municipal sewers. The National Pollution Discharge Elimination System (NPDES)
has proposed discharge limitations for poultry processing plants consisting of: 0.18 kg
(0.40 lb) of 5-day biochemical oxygen demand (BODs )/454 kg (1000 lb) of broUers processed and 0.28 kg (0.62 lb) of suspended solids (SS)/454 kg (1000 lb) of broUers processed.
Slightly higher allowances are made for the processing of heavier birds, referred to as fowls,
increasing the BOD5 load to 0.21 kg (0.46 lb)/454 kg (1000 lb) of birds processed [1].
The present double-digit inflation has increased consumer demand for poultry products
due to their high protein content and low cost. This increased demand has pushed the
poultry processing industry to the limits of its productivity, requiring greater volumes
of production and processing methods of increasing complexity. Two main types of processing exist today: "typical" processing and "further" processing. As a result of the differences
in processing, each operation generates a distinctly different waste stream. The two processes
along with their respective steps and corresponding wastewater characteristics are shown
in Table I [2].
Dissolved air flotation (DAF) with chemical additives has emerged as a viable pretreatment alternative for "typical" poultry processing wastes where blood and/or G&O are
recovered for additional processing at a rendering facility [3). Generally, alum and lime
are the main chemical conditioners employed in flotation for pretreatment of "typical"
plant wastes. Chemical conditioning is necessary to form floe on which to absorb the G&O
which will effectively break the G&O-water emulsions [4]. Alum and lime have been used
as chemical conditioners at doses of 15-30 mg/1 and 100-500 mg/1, respectively [1]. In
addition, various polymers have been used in concentrations ranging from 0.1 to 20 mg/1,
depending on the polymer type [ 1 ]. Operation parameters for pretreatment of a "typical"
poultry processing waste employing DAF are listed in Table II. Reduction in SS and BOD5
concentrations of 81% and 57%, respectively, are common with lime conditioning and
DAF [2].
The objective of this study was to determine if chemical conditioning coupled with
DAF could be applied as a means of pretreatment of effluents from poultry processing
plants engaged in "further" processing. Lime was selected as the primary chemical additive
to be used in conjunction with a cationic polymer. DAF was selected in consideration of
the high levels of G&O present in the raw waste and the potential for by-product recovery,
the sales of which would partially defray the cost of the pretreatment system.
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