Design of A Wastewater Treatment Plant For Paint Factories-1
Design of A Wastewater Treatment Plant For Paint Factories-1
Design of A Wastewater Treatment Plant For Paint Factories-1
ABSTRACT
In order to improve the health and livelihood of the public, there is a need to treat wastewater from the different
sources which include municipal, agricultural and industrial areas. The main purpose of this project is to design a
treatment system that could treat wastewater from Chromatic Paints Factory to dischargeable standards. Sampling
was carried out at the factory, the quality of the wastewater was determined through conducting both in situ and
laboratory tests, flow measurements using a bucket method. The jar test was also carried out to determine the op-
timum alum dosage in the wastewater. The different results from the tests were discussed in relation to the quality
and the quantity of the wastewater generated. Therefore, the different objectives of the research and design project
were met. This report provides an engineered design of the proposed treatment system which comprises the mixing
unit, sedimentation tank, filtration unit. However, the company is advised to continuously monitor the quantity
and composition of their wastewater in order to develop better informed design parameters such as flow rate. It is
also recommended that a better sludge disposal method should be researched about.
Chromatic Paints Factory lacked an efficient treatment Figure 1: Showing the underground pit
system for its wastewater. This led to poor disposal of
untreated wastewater into an underground pit (shown This study was aimed at finding a solution to this prob-
in Figure 1) and on land. According to Part 5(1) of the lem by designing a treatment system for the factory
National Environment Regulation for Discharge of Ef- through wastewater sampling, field and laboratory
fluent into water or onto land, every industry must have tests, analysis and design.
a treatment facility and a regulation of the amount of
waste generated to standards that are not harmful to 1.2 Justification
the environment (NEMA, 1999).
The paint factory does not have a proper effluent dis-
The current method used to manage the wastewater posal management facility for its wastewater. This
presents a big threat of leakages of wastewater into the method of using an underground pit is not sustainable
surrounding environments including water channels and efficient since in the long run it might affect the
and streams downhill which people depend. (Olayinka, soil productivity and its concentrations, hence affect-
2015). Approximately 35% of the population around ing the plant life (Jolly, et al., 2008). In addition to this,
the world depend on different groundwater sources some inorganic waste is not decomposed by anaerobic
which are mostly from shallow aquifers to meet their processes/digestion, these pits are also ineffective at re-
water needs (UNEP, 2002), and this exposes people to moving phosphorus and nitrogen compounds that have
the poisonous pollutants in this wastewater which in- the potential to cause algal blooms in waterways in case
cludes heavy metal, eutrophication especially in water there are leakages (Ground & America, 2008).
channels. Furthermore, some of the components of
these wastes contain chemical elements which are likely Despite the fact that there are regulatory bodies such as
to infiltrate and percolate into the subsurface environ- National Environment Management Authority (NEMA)
ment upon discharge, and these subsequently accumu- in charge of ensuring proper wastewater disposal, Chro-
late into the soil pores (Idzelis, et al., 2006). The compo- matic Paints company does not conform to these set
sition and quality of surface and groundwater has been regulations for effluent discharge.
declining due to the high increase in the industrializa- Therefore, treatment of this waste water using an ap-
tion and human activities (Kumar, et al., 2013). In ad- propriate design in place, effluent will be treated before
dition, as paint wastewater flows as runoff into storm it is discharged, thus reducing the potential risk of con-
drains, the organic solvents and inorganic compounds tamination of underground water and land, hence pro-
are slowly broken down in water, depriving aquatic or- tecting human and plant life.
ganisms of the oxygen they need to survive. The toxic
nature of chemicals in solvent-based paints may also 2.0 METHODOLOGY
cause tumours to form in animals such as fish.
This chapter outlines the research methodology that
was used to conduct the research and inform the design.
It consists of geographic scope and study methodology
applied to achieve the objectives of this research.
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2.1 Geographical and time scope 2.2.2 Field/in situ tests
In order to assess the wastewater quality parameters,
Chromatic Paints Uganda Limited is located on Plot 5, in situ measurements were taken at 2 sampling points
Kasubi-Kawala, off Hoima Road in Kampala District. for the preliminary tests, which were carried out on
20/12/2018.
Time scope: September 2018 to April 2019
Before the wastewater goes into the underground pit,
2.2 Content scope it is first screened to reduce on the suspended solids.
Hence sampled the wastewater both before and after
Investigation of the quality, quantity of the wastewater screening.
from Chromatic Paints Limited. Laboratory and field
tests were carried out to determine the quality of the The first sampling point was at the outlet point of the
wastewater. The wastewater flow rate was also carried wastewater from the factory (before screening) and also
out to determine the quantity generated. The results the wastewater in the underground pit (after screen-
from these tests informed the design of the wastewater ing). This enabled the researcher to know the variations
treatment system. between wastewater parameters and those that needed
improvement. These measurements were carried out
2.2.1 Flow Rate measurements between 4:00 – 5:00 pm with the help of a technician.
The amount of wastewater produced was determined The parameters determined included temperature and
through measurement of wastewater flow at the fac- dissolved oxygen. The above parameters were measured
tory. Flow varies from one day of the week to another using a Mettler Toledo and a DO MRC.
month or season. Most of the wastewater was generat-
ed in the evening when there was cleaning of floors and At each sampling point, the measurement for each of
mixing tanks, leading to high volumes of wastewater the above parameters was conducted in triplicate.
during that time.
The flowrate was determined using a bucket method 2.2.3 Laboratory tests
(shown in Figure 2). The bucket method was chosen in The samples obtained from the field were analysed for
preference to others because it is suitable for small flows parameters such as colour, BOD5, COD, TSS, TKN, Total
and irregular channels and also due to the availability of Phosphorus, Alkalinity, Sulphate. These tests were car-
the equipment required to carry out its procedure. ried out to check whether the parameters of the waste-
water are in relation to the NEMA standards of the ef-
fluent to be discharged to the environment.
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3.1 Wastewater quality characteristics
Table 1: Showing the preliminary results of the wastewater from the factory.
The researcher carried out preliminary tests to deter- before screening, and out of range after screening. This
mine the quality of the wastewater as shown in Table 1 is because after screening, the wastewater is stored in
and the parameters that needed to be improved. an underground pit which is always covered, hence lim-
ited oxygen supply (Metcalf & Eddy, 2003). Dissolved
Biochemical Oxygen Demand (BOD), Chemical Oxygen Oxygen is required in adequate amounts for survival of
Demand (COD), Colour, Total Phosphorus (TP), total aquatic life and prevention of offensive odours.
kjeldahl nitrogen (TKN), Total Suspended Solids (TSS),
and Turbidity. All these were above the effluent dis- 3.2 Wastewater flow rates from Chromatic Paints
charge standards both before and after screening. Factory
The high levels of BOD and COD were as a result of the Below are the results obtained during both production
different organics used in the manufacture of the paint, days and days when cleaning activities took place (Sat-
for example, titanium dioxide, calcium carbonate, mag- urdays).
nesium silicate, cellulose (Gulin, et al., 2004). The colour
was as a result of the organic material that has dissolved Table 2: Showing the varying flow rates
into solution, which leads to high values of the turbidity
(Ibrahim & Gabr, 2014). Day Flow Rate (m3/day)
Monday (4th) 135
Alkalinity and Potential of Hydrogen (pH) were above
the discharge standards before screening, and within Wednesday (13th) 140
the range after screening (Gulen, et al., 2006). This is Friday (21st) 130
because before screening, the wastewater is still rich in Saturday (9th) 180
paint while after screening, some paint is taken off by
Saturday (16th) 190
the screen, hence the low pH.
Saturday (23rd) 185
Sulphate, lead, chromium were not detected. This is be- Average flow rate 160
cause these are water-based paints where water is used
as a solvent. These paints have less traces of heavy met- From Table 2, it is observed that during production
als. days the flowrate was within the range of 130-140 m3/
day while during Saturdays the flowrate was within the
Dissolved Oxygen (DO) was within the discharge range range of 180-190m3/day.
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The peak flow rates were obtained during Saturdays of paint for example calcium carbonate, magnesium sil-
when cleaning activities take place. Therefore, for prop- icate and their reaction with alum. Since the pH did not
er design, calculated the average flow rate which was go above 7.8, that means it was still in the neutral range
160m3/day. This flow rate catered for both minimum and therefore we did not need to adjust it (Philip, 2016).
and peak flow rates.
4.0 LABORATORY SCALE DESIGN
The flowrate measurements kept varying from day to
day and time. This is because the factory works on a The results from the tests carried out informed the
batch process where wastewater only flows when activi- design. A prototype or laboratory scale design was set
ties like production, cleaning are being carried out. Days up and the wastewater was run through the system as
from Monday to Friday are normal working days where shown in Figure 4. The effluent from the system was
more production of paint is carried out than cleaning tested and results obtained to determine its efficiency.
activities. On such days, less is generated therefore lead- The design was important in achieving the last specific
ing to low values of flow rate. objective.
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a representative sample which was the water thereby causing a reduction in the turbidity thus further reduc-
analysed. tion in the BOD.
From the results of the influent and Comparing this design to other designs used in treatment of water-based
effluent, the researcher calculated paints, for example; combination of a chemical coagulation/flocculation
the percentage removal of the sys- step with an aerobic biological process by (Souabi, et al., 2006) which re-
tem in order to determine the effi- moves 92% of COD, 97% of colour and 44.5% of BOD. From this, the pro-
ciency of the system. posed system is more efficient than the one of (Souabi, et al., 2006) because
it has a higher percentage efficiency.
Table 3: Percentage removals for the
different parameters
Parameter % Removal
Colour 99.6
Turbidity 99.8
COD 98.6
BOD 91.4
TKN 99.2
TP 99.8
TSS 99.4
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5.0 CONCLUSION Gulin, K., Fatos, G. & Gulen, E., 2004. Treatability of
The objectives of the project were met within the pro- water based paints. Volume 13 ed. Freising.
posed time schedule. Releasing these loadings directly Ibrahim, M. & Gabr, M., 2014. Desalination and Water.
into the environment leads to a deterioration of land, Reduction of COD in water based paint wastewater us-
water quality in the receiving environment. ing three types of activated carbon.
The factory’s wastewater showed high levels of COD, Idzelis, R., Kristina, G. & Dainius, P., 2006. Investigation
BOD, TSS, colour, turbidity, TP and TKN. The system and evaluation of surface water pollution with heavy
was able to treat the wastewater up to a percentage metals and oil products in Kairiai Military Ground ter-
removal of above 90% for all of the parameters hence ritory. 183-190.
making the system efficient for treatment.
Kumar, D., Chadda, S. & Sharma, J., 2013. Syntheses,
Chromatic Paints Factory produces approximately an spectral characterization, and antimicrobial studies on
average flow rate of 160 m3/day, and this was used in the the coordination compounds of metal ions with schiff
designing the size of the sedimentation tank and other base containing both aliphatic and aromatic hydrazide
units. The optimum dosage of alum obtained from the moieties.
jar test was 300mg/l.
Metcalf & Eddy., 2003. Wastewater Engineering Treat-
ment and Resource Recovery. New York: McGraw- Hill
6.0 RECOMMENDATIONS Education.
• It is also necessary to continuously monitor the MWE, 2013. The Republic of Uganda. Ministry of Wa-
quality of effluent from the treatment system in ter and Environment. Water supply design manual of
order to verify that its quality complies with the na- Uganda. second edition.
tional discharge standards.
NEMA, 1999. The National Environment. Standards for
• It is recommended that more research should be Discharge of Effluent into Water or on Land in Uganda.
carried out in order to get the best way to dispose
of the sludge to the environment. Olayinka, O., 2015. Preliminary assessment of effects of
paint industry effluents on local groundwater.
• It is recommended to carry out continuous mea-
surements for the flow rate so as to obtain records Peta, T., 2006. Efficiency of activated carbon filters in
of at least one year in order to develop an accurate COD reduction.
peak to average flow rate factor.
Souabi, S., Aboulhassan, M., Baudu, M. & Hazard, M.,
2006. Improvement of paint effluents coagulation using
REFERENCES natural and synthetic coagulant aids.
APHA, 2005. America Public Health Association. Water Summit, M., Phansiri, M. & Wanwinom, P., 2015.
and Wastewater examination. America. Characterization and Properties of Activated Carbon
Prepared from Tamarind Seeds by KOH Activation for
EPA. Environment Protection Agency,. 1995. Water Fe(III) Adsorption from Aqueous Solution. Thailand.
Treatment Manuals Filtration.
Gulen, E., Goksen, S. & Germirli, B., 2006. Coagula-
tion-Flocculation of Wastewaters from a Water-Based
Paint and Allied Products Industry and its Effect on In-
ert COD. Volume 41.
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