New poultry plant wastewater facility reduces costs and allows for future expansion
Floccin feeder with supersack.
The facility to be discussed
processes, seasons, cooks, and
flash-freezes poultry for the
food industry and was trying
to increase their production. Their previous
wastewater system was limited
in its ability to meet the discharge
requirements to the local Publicly
Owned Treatment Works (POTW) and
was required to meet these more stringent
limits as a condition of their
expansion. To expand production, the
facility was looking at a tremendous
capital improvement cost to increase
the size of their wastewater pretreatment
plant to handle the expected
higher flows and loadings.
The facility had problems with levels
of Total Dissolved Solids
(TDS)/Electroconductivity (EC), wet
sludge that was expensive to dispose
of, poor coagulation/flocculation control,
carry-over of floc into their effluent,
throughput limitations due to the
poor coagulation/flocculation performance,
high chemical costs, among
others. In addition, the POTW was
planning to levy surcharges for
EC/TDS due to their noncompliance
with their US EPA regulated discharge
permit.
Prior Operations
On the average, the facility treated
180,000 USgpd, operating 101/2 hours
per day, five to six days per week.
Wastewater from the various poultryprocessing
operations flows to a common
sump and is then pumped through
a rotary screen (to remove the large
solids) and flows to a 180,000 gallon
Equalization Tank (EQ Tank). The
wastewater is pumped from the bottom
of the EQ Tank at 275-300 gpm to their
Dissolved Air Flotation (DAF) system.
The wastewater was pH adjusted (inline)
with caustic or acid to meet the
near neutral setpoint of 7-8 pH. After
pH adjustment, an aluminum based
inorganic/organic coagulant was
added, followed by cationic and anionic
flocculants. The wastewater is
mixed/flocculated in the DAF floctubes
with dissolved air addition and the float solids rise to the surface. The
solids are skimmed off and pumped to
an 8,000 gallon holding tank and the
treated liquid effluent flows to the
city’s wastewater facility.
The effluent water quality from the
facility to the city averaged a flow of
200,000 USgal/day, a BOD of 1,200
mg/L and a TSS of 500 mg/L.
Table 1 — Discharge wastewater quality
Prior Process
The process used five chemicals:
caustic, acid, coagulant, cationic flocculant,
and an anionic flocculant. The
operator spent several hours each day
transporting, blending, mixing, and
adjusting the feed rates of these different
chemicals. The treatment process
required tight pH control for effective
coagulation/flocculation, but this is
very difficult to maintain due to the
various products they process inside
the plant. When the pH is out of the 7-
8 range, the effluent water quality
decreases and the resulting sludge is
difficult to handle due to its wet and
slimy nature.
The sludge was being hauled off at
an expense of $15,000 per week. The
facility attempted to dewater the
sludge, but the chemistry in use did not
allow release of the water entrained in
the sludge.
Prior Chemical Usage Rates
In an average month the processor
used eight drums each of caustic and
acid; 3,300 gals of coagulant, and
2,000 lbs each of the cationic and
anionic flocculants. The average
monthly chemical cost was $18,000
and the sludge haul off cost was
$60,000. In addition, there was an
impending surcharge from the POTW
for BOD, TSS, and EC.
The Trial using Floccin-J
The addition of the Floccin-J product
required some small changes in the
system’s operation. In order to feed
product into a pressurized line, the
Floccin Feeder system was modified:
the auger of a standard feeder was set to deliver product into a second “slurry
tank.” (Makeup water for the slurry
tank was taken right from the wastewater
line exiting the EQ tank.) After
mixing, the slurry was pumped
straight into the DAF feed line
upstream of the flocculation tubes. The
resultant effluent quality was greatly
improved, as shown in Table 1. The
DAF cake was more consistent, much
drier, less shear sensitive, and more easily dewatered than with the previous
chemistry. The pH swings from 4.7
to 10.8 and the Floccin-J works very
well even with these pH swings. With
the increased solids content, sludge
disposal costs were reduced from $900
per load to $600 per load.
Trial Results
The goals for the trial were:
To optimize the treatment process
and allow increased production without
capital outlay.
To simplify the wastewater treatment
process, reducing the operators’
workload and dangerous chemical
exposure.
To reduce the EC/TDS in the
effluent and avoid/minimize proposed
surcharges from the city.
To increase the solids-content of
the sludge and reduce sludge disposal
costs.
Reduce the overall treatment
costs.
The trial was successful in meeting
all of these objectives.
Table 2 — Cost comparison
Benefits
The use of Floccin-J reduced the
number of on-site chemicals from 5 to
2. Floccin-J works in a wide range of
pH values (4.7 to 10.8) and is much
easier to control; the operator simply
adjusts one speed-control dial instead
of several chemical feed pumps.
DAF with drier sludge.
The cost of using the traditional
chemistry was $4,163/day as compared
to $2,725/day with Floccin-J. Soon
after the trial, the facility started up a
batter frying line that increased the
BOD by 30% (part of the plant expansion).
Integrated Engineers reformulated
a special product (Floccin-G) for the
facility and reduced the usage rate to
25% lower than Floccin-J. An additional
cost savings was in the operation of
the EQ tank and the use of carbon dioxide
instead of acid to control the pH
(also reduced the EC/TDS levels).
Another area of savings was from the
conservation of water in the plant
processes reducing the water consumption
50% (200,000 gpd reduced to
100,000 gpd). The facility is also benefiting
from the reduction in Insurance
and Workman’s Compensation premiums
due to the elimination of the hazardous
chemicals.
Conclusion
Floccin-J has simplified the system,
allowing the poultry processor to run a
more consistent process, obtain better
quality effluent and sludge – with less
operator intervention. The daily chemical/
sludge hauling costs have been
reduced by 34%. Best of all, the
processor is free to move forward with
increased production without the
expense of expanding the wastewater
treatment plant, buy additional capacity
units from the POTW, and has
reduced costs with lower surcharges.
