Chemical treatment of poultry abattoir wastewater
By
Fabrice Pellegrin & A.K. Ragen
Contents of Presentation

Introduction

Aims & Objectives

Methodology

Results & Discussion

Conclusions & Recommendations
Introduction

From the year 2000 to 2006 the poultry production in Mauritius
had increased by 40.6 %

Two major slaughterhouses in Mauritius operating on an
industrial scale

One of these abattoirs processes about 30,000 birds per day

Poultry slaughterhouses make use of significant quantity of high
quality water for their operations

About 88 % of the water intake is directly converted into
wastewater with a strong organic content

The strong organic wastewater generated contains high levels
of oil & grease, total suspended solids (TSS) and nutrients

With the introduction of norms on limiting wastewater
discharge, it is now a legal requirement for poultry
slaughterhouses in Mauritius to treat their wastewater to such
quality to meet discharge norms
Discharge parameters to be complied with by poultry abattoirs
Parameter
Maximum permissible
concentration
Chemical Oxygen Demand
1500 mg/l
Chloride (as Cl-) and
1500 mg/l
sulphate
as SO42- combined

pH
5-9
Total suspended solids
400 mg/l
Oil & grease
150 mg/l
The abattoir under study is equipped with a Dissolved Air
Floatation System (DAF) as means of treatment to remove
pollution from the wastewater
Abattoir Processes

Stunning: process whereby birds are made insensible before
slaughtering

Neck severing

Scalding: wetting & partially removing the birds feathers

Plucking

Evisceration: the purpose of evisceration is to remove all the
thoracic & abdominal organs and separating the edible viscera
from the inedible ones

Spin chilling: to chill & disinfect the carcasses before packaging
Aims & Objectives

To determine the specific water intake (SWI) of the abattoir

To characterize the outgoing wastewater streams in terms of COD,
pH, chloride, TSS and oil & grease

To carry out standard jar tests to determine the optimum
conditions of various chemicals on the wastewater

To find a proper way to dispose of the blood generated by the
slaughtering of chicken
Methodology
1. Determination of Specific Water Intake (SWI)
The SWI was determined by:

taking the readings of the CWA flowmeter connected on the
supply line to the abattoir on each working day for a period of
one month

Recording the amount of birds processed on each working day
over the same period
2. Characterization of Wastewater Streams
Poultry Abattoir Sewer Map showing sampling locations
Sampling of wastewater streams

13 composite samples were taken each day for 5 days (In all 65
samples were taken)

Composite sampling was chosen to eliminate possible errors
that might have occurred due to:
1.
An irregular flow of birds on the line shackles
2.
An irregular water flow inside the abattoir
Preservation of Samples
Parameter
Container
Preservation
Maximum
Holding Time
Chloride
P,G
None required
28 days
Nitrate
P,G
Cool, 4oC
48 hours
Oil and grease
G
Cool, 4oC
28 days
H2SO4 to pH < 2
TSS
P,G
Cool, 4oC
7 days
BOD
P,G
Cool, 4oC
48 hours
COD
P,G
Cool, 4oC
28 days
H2SO4 to pH < 2
Hydrogen ion
P,G
None required
(pH)
Turbidity
Analyze
immediately
P,G
Cool, 4oC
7 days
Methods of Analysis

Chloride was determined using the Mohr`s method as per the ISO
9297:1989(E) standard

All the other parameters were analyzed by means of the US-EPA
approved Hach DR/2000 spectrophotometer.
3. Jar Test Experiments

The wastewater samples for jar tests were taken on 5 days (each day
25 L of grab sample was collected)

Grab sampling was chosen because composite sampling might have
obscured some important parameters such as turbidity and pH

The jar tests were carried as per the ASTM D 2035 – 80 (2003)
method

Coagulants used were Ferric chloride (FeCl3), Sodium
Hexamethaphosphate (HMP), Alum, Primco 730 and Primco 738 and
flocculent used was Nalco 9617
Collection of wastewater sample at
effluent treatment plant
Carrying out of Jar test Experiments
 Each time a coagulant was used the optimum dosage was
determined by the turbidity test

The tests were repeated by placing the same optimum coagulant
dosage in each beaker but that time the pH of the wastewater was
varied (different pH in each beaker)

Most of the time, when the optimum coagulant dosage was
determined (with or without change in pH), the tests were
repeated by placing the same optimum coagulant dosage in each
beaker and different doses of Nalco 9617 (flocculent) were added
to the beakers
Results & Discussion
1. SWI results
 The SWI varied from 14.3 to 28.4
L/bird
 The figure illustrates 4 peaks in the
SWI at 28.4, 25.6, 22.3 & 24.8 L/bird
 These peaks may be explained by
the fact that on those days fewer
birds were processed but the same
amount of water was used
 The average SWI = 17.9 L/bird
Variations in SWI per bird over a period of one month
2. Effluent streams characterization results
pH
Sampling
COD
Oil & grease
TSS
Chloride
(mg/l)
(mg/l)
(mg/l)
(mg/l)
Range
mean
Range
mean
Range
mean
Range
mean
Range
mean
Killing
6.45 -
6.47
5230 -
5840
536 -
575
1745 -
2099
165.1-
179.5
section (S2)
6.65
Evisceration
6.70 -
section (S8)
6.85
Spin chilling
7.74-
section (S11)
7.87
Live dock
9.30-
section (S12)
9.47
location
6260
6.77
3870-
604
4205
4425
7.79
3425-
2420-
3440
414
474
3905
4330
9.38
302-
2325
28.3-
12.3-
21
705
745
36.8
43.0
3075
664-
195.3
515-
196-
237
86.4
104.9
593
685
16.8
72.7-
137.2-
148
156
220
72.8-
99.5
 The pollution load in some streams varied quite widely
 The cause of such variations was probably due to an irregular flow
of birds on the line shackles at some time when the wastewater
samples were taken
87.2
Summary of characterization results from the
different sections
 The COD load from 4 streams in the evisceration section
complied with the discharge norms
 1 Stream from the killing section and 2 streams from the
evisceration section did not comply with the discharge norms in
terms of oil and grease
 The TSS load from 4 streams in the evisceration section
complied with the discharge regulations
 4 Streams were not polluted these were the outlet from the vent
opener (S3), neck cracker (S5), inside outside washer (S7) &
spin washer 2 (S10)
Result of the characterization of the final effluent
Parameter
Pollution
range
Mean
pollution
load
Discharge
limit
pH
6.51 – 6.72
6.63
5–9
COD (mg/l)
3885 – 4685
4230
1500
Oil & grease 44.3 – 163.2
(mg/l)
57.2
150
TSS (mg/l)
605 – 930
789
400
Chloride
67.5 – 92.3
76.8
1500
 The highest value for oil & grease occurred because on one
sampling day the rotary screen at the treatment station was not
working
 The TSS and the COD loads did not comply with the discharge
norms
3. Jar Tests Results
Combinations of coagulants and Nalco 9617 dosages
giving lowest turbidity
Combinations of Coagulants and
Turbidity (FTU)
Nalco 9617
225 ppm FeCl3 + 10 ppm Nalco 9617
29
175 ppm HMP + FeCl3 (1:1) mixture +
23
15 ppm Nalco 9617
175 ppm HMP + 15 ppm Nalco 9617
40
325 ppm Alum + 10 ppm Nalco 9617
62
 Lowest turbidity with combination of 225 ppm FeCl3 & 10
ppm Nalco 9617
 The combination of 325 ppm of alum + 10 ppm Nalco 9617
gave the highest turbidity
Comparison of the efficiency of chemicals on the
effluent in terms of pH
Coagulants
Best working
Resulting turbidity
pH range
range
(FTU)

FeCl3
5.3 – 6.0
38 – 79
HMP + FeCl3 (1:1)
3.3 – 4.3
21 – 28
HMP
3.5 – 4.5
18 – 65
Alum
6.0 – 8.0
40 – 82
Alum gave better results at a higher pH range than the other
coagulants and the mixture of FeCl3 + HMP gave appreciable
turbidity results at a low pH range
% pollutant removal
Comparison of Efficiency of combinations coagulants &
Nalco 9617
100
95
90
85
80
75
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
% COD
removal
% TSS
removal
%Turbidity
removal
FeCl3
FeCl3 +
HMP
HMP
Alum
% COD removal
75.3
80.1
87.7
65.1
% TSS removal
98.8
96.9
98.1
97.2
%Turbidity removal
97.5
95.8
97.1
92

The combination of HMP & Nalco 9617 removed the highest
percentage of COD from the wastewater

The combination of FeCl3 & Nalco 9617 removed the highest
percentage of turbidity and TSS
Cost of effluent treatment per m3
Combinations of chemicals
Cost of treatment
(Rs/m3)
FeCl3 + Nalco 9617 + HCl
14.48
50 % FeCl3 + 50 % HMP + Nalco
26.43
9617 + HCl
HMP + Nalco 9617 + HCl
27.30
Alum + Nalco 9617 + HCl
16.55

Least cost is obtained by treating the effluent with a combination
of FeCl3 + Nalco 9617

Highest cost is obtained by treating the effluent with chemical
combinations containing HMP
Raw effluent
Effluent treated with FeCl3
Effluent treated with HMP
Effluent when treated with alum
Conclusion & Recommendations
Conclusions:

The SWI was found to be 17.9 L/bird

Wastewater streams S3, S5, S7 & S10 completely complied with
the discharge regulations

The combination of HMP + Nalco 9617 removed the highest
percentage of COD whereas the combination of FeCl3 + Nalco
9617 removed the highest percentage of turbidity & TSS

Treating the effluent with combinations containing HMP would
be more expensive
Recommendations:

All hoses should be fitted with self-closing nozzles to eliminate
wastage when not in use

The effluents from streams which completely conforms with the
discharge regulations amounts to 96 m3/day. This 96 m3 of
effluent can be directly sent to the sewer network or use to rinse
the blood in the blood trough during the neck severing process
Further research:

Determining the best disposal option for the 96 m3 of effluent
which completely conforms with the discharge regulations