International Journal of Water Resources and
Environmental Engineering
Vol. 5(5), pp. 272-279, May, 2013
DOI IJWREE-23.03.13-0401
ISSN 2141-6613 © 2013 Academic Journals
http://www.academicjournals.org/IJWREE
Full Length Research Paper
Water quality assessment of a wastewater treatment
plant in a Ghanaian Beverage Industry
Emmanuel Okoh Agyemang1*, Esi Awuah2, Lawrence Darkwah3, Richard Arthur1 and Gabriel
Osei4
1
Energy Systems Engineering Department, Koforidua Polytechnic, P. O. Box KF981, Koforidua, Ghana.
Civil Engineering Department, Kwame Nkrumah University of Science and Technology (KNUST) Private Mail Bag,
Kumasi, Ghana.
3
Chemical Engineering Department, Kwame Nkrumah University of Science and Technology (KNUST) Private Mail Bag,
Kumasi, Ghana.
4
Mechanical Engineering Department, Koforidua Polytechnic, P. O. Box KF981, Koforidua, Ghana.
2
Acceptance 16 April, 2013
The research is aimed at assessing the performance of the wastewater (excluding sewage) treatment
plant in a Ghanaian beverage industry. Sixteen (16) water quality parameters were analyzed by
collecting influent and effluent wastewater samples of the treatment plant for a year and their average
values were compared with EPA (Ghana) guidelines for beverage industries discharging into water
bodies. Most of the effluent wastewater pollutant content met the set guidelines, while others were
unacceptable. However, the ability of the wastewater treatment plant to effectively deal with key
pollutant such as BOD (93%), Ammonia (82%) and COD (82%) suggests that the treatment plant is
efficient. In order to improve on the final effluent quality, sand filters may be introduced after the
Sequential Batch Reactor II before final discharge into the environment.
Key words: EPA guidelines, de-sludging, environment, sand filters, wastewater.
INTRODUCTION
The importance of water in all facets of life cannot be
over emphasized. It is vital for consumption, health and
dignity. It is a fundamental resource for human
development, especially residential area location. The
development of any city has practically taken place near
some source of water supply (Rangwala et al., 2007).
The ever increasing levels of pollutants and complexity of
effluents from municipality and industry, demand effective
technologies to reduce pollutants to the desired levels.
The use of current wastewater treatment technologies for
such reclamation is progressively failing to meet required
treatment levels. Advanced wastewater treatment
technologies are essential for the treatment of industrial
wastewater to protect public health and to meet water
quality criteria for the aquatic environment and for water
recycling and reuse (Agyemang, 2010).
The protection of receiving waters is essential to
prevent eutrophication and oxygen depletion in order to
sustain fish and other aquatic life. Discharge of untreated
effluent wastewaters into water bodies may put at risk
riparian communities that depend on these waters for
domestic and personal use (Tchobanologous et al.,
2003). Though treated wastewater may not comply with
drinking water standards, contacts with water carrying
*Corresponding author. E-mail: doc.okohmet@yahoo.com.(Tel +233 244838560; 279829918)
Agyemang et al.
273
high pathogenic loads may potentially lead to the
transmission of enteric infections (Kamala and Kanth
Rao, 2002).
The wastewater treatment plant discharges close to
3
500 m /day of treated effluent to an open channel that
leads to the Atonsu stream. Downstream are a number of
riparian communities that rely on the stream for bathing,
cooking, drinking, irrigation and cleaning. The main
objective of the study is to conduct an assessment on the
quality of the treated wastewater effluent that is
discharged into the Atonsu stream. This objective was
achieved through physical, chemical and biological
analysis of the effluents and the standards compared with
EPA (Ghana).
to receive and balance shocks such as high pH and temperature
levels. The basin has a retention time of 8 h. From the basin water
is pumped to the sequential batch reactor I for subsequent
treatment to be effected.
METHODOLOGY
Sequential batch reactor II
Wastewater sources
From the sequential batch reactor I, wastewater is pumped to the
sequential batch reactor II for further treatment to be effected. The
sequential batch reactor II is also circular in shape, has a capacity
of 780 m3 and is made of stainless steel. The second reactor is
employed to further breakdown organic and inorganic compounds
present in the wastewater by the use of bacteria. It is automatically
operated and desludging is done periodically. Treated effluent
wastewater is finally discharged into the Atonsu stream.
Wastewater (excluding blackwater and urine) generated in the plant
is channeled into a central concrete drain that leads to the pretreatment tank of the treatment plant. Sources of wastewater
generated in the plant includes wastewater generated from cleaning
the production floors, washing of process equipment (mixing tanks,
storage vessels, holding tanks, etc.), washing and rinsing of
beverage bottles, washing and cleaning laboratory floors and
equipment and wastewater generated from the kitchen.
Sequential batch reactor I
The sequential batch reactor I is circular in shape, has a capacity of
780 m3 and is made of stainless steel. The reactor contains bacteria
employed to feed on the high concentration of organic and
inorganic compounds present in the wastewater. The bacteria
convert the colloidal and dissolved carbonaceous organic matter
into various gases and cell tissue. The resulting cell tissue is
removed from the treated wastewater by gravity settling. The
reactor is automatically operated and desludging is done
periodically. Wastewater is retained for 8 h.
Wastewater sampling and analysis
Wastewater treatment plant
The wastewater treatment plant is the batch type and consists of
four main components; the pre-treatment tank, balancing equalizing
and neutralization basin, the sequential batch reactor I and
sequential batch reactor II. Figure 1 presents the layout of the
wastewater treatment process at the beverage plant.
Sampling was done monthly starting from August 2009 to July
2010. Twenty-four (24) samples representing twelve (12) influent
and twelve (12) effluent samples were analysed. Temperature of
the samples was measured in-situ. Parameters that were analyzed
include BOD, COD, turbidity, colour, pH, temperature, total
dissolved solids, total suspended solids, conductivity, coliforms,
nutrients and trace metals. Table 1 presents the methods and
instruments used for the water quality analysis.
Pre-treatment tank
The pre-treatment tank is an underground rectangular concrete
tank with the capacity of 280 m3 and consists of three main
sections. The first section removes wastewater constituents that are
likely to cause operational problems during the treatment process.
This includes screening for the removal of debris, crown corks,
straws, rags, grit and flotation for the removal of small quantities of
oil and grease. The second section is the neutralization basin and is
equipped with an automatic pH meter that corrects the pH of the
wastewater by dosing sulphuric acid when it is necessary. It also
contains mechanical agitators which continuously stir the
wastewater to ensure a uniform pH within the chamber. The third
section is the neutralized tank and is equipped with submersible
pumps to automatically pump the wastewater when it gets to a set
maximum limit.
Balancing neutralizing and equalizing basin
The balancing, neutralization and equalization basin receives
preliminary treated wastewater from the pre-treatment tank and is
automatically controlled. It is circular in shape, has a capacity of
780 m3 and is made of stainless steel. The basin serves to
neutralize the wastewater pumped from the pre-treatment tank and
RESULTS AND DISCUSSION
Wastewater characteristics
The mean value of each water quality parameter
considered for both influent and effluent wastewater
samples have been computed and tabulated (Table 2) as
well as the standard deviation and standard errors of
95% confidence interval.
Temperature
The temperature of the influent wastewater to the
treatment plant ranged from 47 to 50°C and with a mean
of 48.2°C. The effluent temperature ranged from 28 to
30°C. The drop in the effluent temperature could be due
to heat losses by convection to the atmosphere and
conduction to the walls of the receiving treatment tanks.
A drop in temperature is paramount to aiding bacterial
274
Int. J. Water Res. Environ. Eng.
Figure 1. Layout of wastewater treatment process at the Beverage Plant. (a) Influent wastewater (b) Pre-treatment tank (c) Centrifugal
pump (d) Balancing equalizing neutralizing basin (e) Centrifugal pump (f) Sequential batch reactor I (g) Centrifugal pump (h) Sequential
batch reactor II (i) Effluent wastewater.
Table 1. Methods and instruments used for water quality analysis.
Parameter
BOD
COD
Turbidity
Total dissolved solids
Total suspended solids
Ammonia-Nitrogen
Sulphates
Trace metals
Temperature
pH
Colour
Coliforms
DO
Method used
Winkler modification
Closed Tube method
APHA Standard method (USEPA)
Cyberscan PC 300 Series
Cyberscan PC 300 Series
Gravimetric method
Titrimetric method
Membrane Filtration method
-
activities in the treatment tanks. The mean effluent
temperature of 29°C was below the EPA Ghana guideline
of 30°C.
pH
All the influent wastewater samples analyzed were
alkaline. The mean pH value was 11.3 and was in the
range of 10.8 to 11.6. The mean pH values of the effluent
wastewater ranged from 7.9 to 8.9 and were all within
EPA Ghana guideline range of 6 to 9. The decrease in
the pH value of the effluent wastewater indicates that
some form of treatment had been achieved. The
decrease in the effluent pH value could be attributed to
the dosing of sulphuric acid to the influent wastewater at
the pre-treatment section of the treatment process, in
order for biological processes to be effected.
Conductivity
Generally conductivity of water is determined to ascertain
Instrument used
HACH Model 2100P Turbidimeter
Cyberscan PC 300 Series
Cyberscan PC 300 Series
Micro Kjeldhal method
HACH Type DREL/2010 Spectrophotometer
A.A.S 220 model
Thermometer
Cyberscan PC 300 series pH meter
Nesselerizer
Membrane filter
Oximeter
the ability of the waters to conduct electrical current. The
mean influent conductivity value ranged between 1750
and 1999 µS/cm and was 1750 µS/cm. The high influent
conductivity values may be attributed to the high
concentration of dissolved ions present in the wastewater
during the bottles washing stage of the bottle preparation
process. Mean effluent conductivity was 842.8 µS/cm in a
range from 923 to 756 µS/cm. Even though the drop in
conductivity shows some amount of ion removal, the
conductivity levels of the effluents wastewater were
unsatisfactory compared to EPA (Ghana) guideline value
of 750 µS/cm.
Turbidity
Turbidity, a measure of the light transmitting properties of
wastewater, is a test used to indicate the quality of
wastewater discharges with respect to colloidal and
residual suspended matter. High levels of turbidity in
industrial effluents contribute large amounts of
suspended solids to receiving waters. The mean influent
turbidity value was in the range of 39 and 57 NTU and
Agyemang et al.
275
Table 2. Wastewater characteristics.
Parameter
Temperature (°C)
TDS (mg/l)
Conductivity (µS/cm)
Colour (TCU)
TSS (mg/l)
Turbidity (mg/l)
DO (mg/l)
pH
BOD (mg/l)
COD (mg/l)
NH3-N (mg/l)
Sulphate (mg/l)
Cadmium (mg/l)
Copper (mg/l)
Lead (mg/l)
Coliforms (mg/l)
Mean Influent
48.2±0.7
862.2±56.1
1750.1±100.6
77.8±36.0
87.7±27.8
46.8±3.8
3.6±0.6
11.3±0.2
1116.8±192.7
3114.2±252.7
11.5±1.1
60.6±24.2
0.0±0.0
0.0±0.0
0.0±0.0
5466.7±1952.5
Mean Effluent
28.3±0.3
839.8±59.3
842.8±58.8
100±41.3
176.7±114.3
94.8±67.8
5.7±0.6
8.5±0.3
49.8±32.9
569.2±115.9
2.1±0.3
177.7±17.7
0.0±0.0
0.00±0.0
0.0±0.0
15850±6377.1
EPA Ghana (2000)
30
<1000
750
100
<50
75
<1
6-9
<50
<250
1.0
250
<0.02
1
<1
400
200
180
Turbidity (mg/l)
160
140
120
100
80
EPA GUIDELINE
60
40
20
0
Influent
Effluent
Figure 2. Influent and effluent turbidity and EPA guideline.
was 46.8 NTU. The final effluent turbidity value was in the
range of 32 and 225 NTU. The mean effluent turbidity
value of 94.8 NTU was above the EPA Ghana guideline
value of 75 NTU. The mean effluent turbidity value could
be attributed to incomplete sludge settlement during the
sedimentation stage of SBR. Figure 2 is a plot of the
mean influent and effluent turbidity results and the EPA
Ghana guideline.
Colour
Various beverage processing activities such as
production floor cleaning and bottle washing impart
considerable amount of colour to water. Mean colour
value for the influent wastewater ranged from 25 to 150
TCU respectively with the mean of 77.8 TCU. The mean
final effluent colour was 100 TCU and ranged between 60
276
Int. J. Water Res. Environ. Eng.
to 180 TCU. Mean effluent colour value was consistent
with EPA guideline of 100 TCU. However, some high
effluent values of colour recorded during the effluent
sampling time could be attributed to incomplete sludge
settlement during the sedimentation stage of sequential
batch reactor.
Dissolved Oxygen (DO)
Dissolved oxygen is required for the respiration of aerobic
microorganism as well as all other aerobic life forms.
Mean influent DO ranged from 1.8 to 4.8 mg/l and was
3.6 mg/l. Mean effluent DO was 5.7 mg/l and ranged from
4.8 to 6.4 mg/l. The increase in the effluent DO may be
attributed to the infusion of air by blowers during the
wastewater treatment period. Both the influent and
effluent DO values were consistent and above the EPA
Ghana guideline value of 1 mg/l. Figure 3 is a plot of the
average influent and effluent DO results and the EPA
Ghana guidelines.
BOD results and the EPA Ghana guideline. The result of
the average effluent signifies that the biological method is
able to treat the wastewater by means of biodegradation
of organic matter. It is noted that the release of excess
amounts of organic matter into receiving waters could
result in a significant depletion of oxygen and subsequent
mortality of fishes and other oxygen dependent aquatic or
marine organism. The percentage removal achieved was
93%.
Chemical Oxygen demand (COD)
The mean influent COD value ranged between 2466 mg/l
to 3760 mg/l and was 3114.2 mg/l. The mean effluent
COD was between 450 mg/l and 856 mg/l respectively
with a value of 569.2 mg/l. Even though all the effluent
COD values were low as compared to the influent values
none met the EPA Ghana guideline value of 250 mg/l.
The effluent values could be attributed to the presence of
sulphides, sulphites, thiosulphate and chlorides that
cause interferences to COD. The removal efficiency was
82%.
Total dissolved solids (TDS)
Total dissolved solids consist of both the organic and
inorganic molecules and ions present in the true solution
of the water. Mean influent TDS value ranged from 771 to
991 mg/l and was 862.2 mg/l. Mean effluent TDS value
was 839.9 mg/l and ranged from 720 to 923 mg/l. It was
noted that both average influent and effluent TDS results
were consistent with the EPA Ghana guideline for
beverage industries discharging into water bodies.
Total suspended solids (TSS)
The mean influent TSS value ranged from 44 to 144 mg/l
and was 87.7 mg/l. The mean effluent TSS value ranged
from 71 to 380 mg/l and was 176.7 mg/l. The mean
effluent value of 176.7 mg/l was more than the EPA
Ghana guideline value of 50 mg/l. The high mean effluent
TSS value could be attributed to incomplete sludge
settlement during the sedimentation stage of SBR. Figure
4 is a plot of the average influent and effluent TSS results
and the EPA Ghana guideline.
Biochemical Oxygen demand
The influent BOD concentration of the treatment plant
ranged from 700 to 1504 mg/l, with a mean of 1116.8
mg/l. The high values of BOD in the influent wastewater
may be attributed to the high concentration of the organic
matter content in the wastewater. The mean effluent BOD
concentration was 49.8 mg/l and in the range of 19 to 120
mg/l. Figure 5 is a plot of the average influent and effluent
Ammonia-Nitrogen (NH3-N)
The mean influent ammonia value ranged from 9.1 mg/l
to 15 mg/l and was 11.5 mg/l. The mean effluent value
was 2.1 mg/l and ranged from 1.7 mg/l to 2.8 mg/l. The
initial rise in ammonia of the influent quality could be due
to the presence of ammonia is a by-product of anaerobic
digestion whilst the fall in the effluent values could be due
to nitrification and de-nitrification processes. The
percentage removal achieved was 82%. The average
effluent result was above EPA Ghana set guideline.
Sulphates
Mean influent sulphate concentration ranged from 30 to
150 mg/l and was 60.6 mg/l. Also the mean effluent
sulphate concentration was 117.7 mg/l and ranged from
80 to 130 mg/l. Both influent and effluent sulphate
concentration results obtained during the sampling period
were in the range of EPA Ghana set guideline of 250
mg/l. The increase in the sulphate concentration of the
effluent wastewater could be attributed to the dosing of
sulphuric acid during the wastewater pre-treatment stage
in order to bring the pH down for biological activities to be
effected.
Cadmium
The mean influent cadmium concentration was 0.0 mg/l
and the effluent cadmium concentration 0.0 mg/l. The
effluent quality is acceptable according to EPA Ghana
Agyemang et al.
277
7
6
DO (mg/l)
5
4
3
2
EPA GUIDELINE
1
0
Influent
Effluent
Figure 3. Influent and effluent DO and EPA guidelines.
350
300
TSS(mg/l)
250
200
150
100
EPA GUIDELINE
50
0
Average Influent
Average Effluent
Figure 4. Influent and effluent TSS and EPA guideline.
guideline of <0.02 mg/l.
lead concentrations results obtained were below the EPA
Ghana guideline of 1 mg/l.
Copper
Coliforms
The mean influent copper concentration was 0.0 mg/l and
the mean effluent was 0.0 mg/l. Both influent and effluent
copper concentration were within the EPA Ghana
guideline of <1 mg/l and was satisfactory.
Lead
The mean influent lead concentration was 0.0 mg/l and
the mean effluent was 0.0 mg/l. Both influent and effluent
The mean influent coliforms count ranged from 0.26E+04
to 1.02E+04 C/100 ml and registered an average of
0.55E+04 C/100 ml. The effluent coliforms count ranged
from 0.55E+04 to 2.54E+04C/100 ml with an average of
1.66E+04 C/100 ml. The low influent coliform
concentration could be due to the fact that at a high pH
and temperature, most coliform group die or remain
inactive. Although it was expected that the total number
of effluent coliforms be reduced after treatment the reverse
278
Int. J. Water Res. Environ. Eng.
1600
1400
BOD (mg/l)
1200
1000
800
600
400
EPA GUIDELINE
200
0
Influent
Effluent
Figure 5. Influent and effluent BOD and EPA guideline.
30000
Coliforms (N/100ml)
25000
20000
15000
10000
5000
EPA GUIDELINE
0
Influent
Effluent
Figure 6. Influent and effluent coliforms and EPA guideline.
was observed. The increase in the effluent coliform
concentration could be attributed to the high organic
matter content (>20 mg/l BOD) in the treatment tank
which serves as food for the bacteria to grow,
proliferating rapidly in numbers, the small number of
predators in the treatment tanks to devour the bacteria or
on the grounds that the treatment tanks have not been
desludged since its working life. Figure 6 is a plot of the
average influent and effluent coliform results and the EPA
Ghana guideline.
removal efficiencies of key parameters such as
conductivity, BOD, COD and ammonia were between 50
and 100%. The wastewater treatment plant is efficient;
however parameters such as total coliforms, TSS and
turbidity were unsatisfactory. By recommendation, a slow
sand filter may be introduced after the sequential batch
reactor II to improve the effluent wastewater quality.
Tanks within the treatment units should be desludged in
order to improve on the effluent wastewater quality.
Consequently disinfection of the effluent wastewater may
be carried out before final discharge into the Atonsu
stream.
CONCLUSION AND RECOMMENDATION
The wastewater treatment plant has a high potential of
removing key pollutants and could be used for better
treatment of wastewater if managed properly. The
REFERENCES
Rangwala SC, Rangwala KS, Rangwala PS (2007). Water Supply and
Sanitary Engineering, Environmental Engineering. 22nd edition,
Agyemang et al.
Charotar Publishing House, pp. 11- 58.
Agyemang EO (2010). Water auditing of a Ghanaian beverage plant,
MSc. Thesis. Kwame Nkrumah University of Science and Technology
(KNUST), Kumasi, Ghana.
Tchobanologous G, Burton FL, Stensel HD (2003). Wastewater
Engineering Treatment and Reuse, 4th Edition, McGraw Hill, Boston,
U.S.A.
279
Kamala A. Kanth Rao DL (2002). Environmental Engineering: Water
Supply, Sanitary Engineering and Pollution. Tata McGraw-Hill
Publishing Company limited, New Delhi, pp. 48-57.
EPA Ghana (2000). General Environmental Quality Standards (Ghana),
Regulations 2000, pp. 8-13.