7/30/2019 MSC Presentation 1312
1/23
Pollutants of Textile Wastewater
and Their Effects on Environment
ByProf. Dr. Engr. Md Mahbubul Haque
7/30/2019 MSC Presentation 1312
2/23
IntroductionLot of textile processing industries was established to
cater the RMG sector of Bangladesh.
Most of the installed factories are spinning, weaving,
denims, knitting and knit dyeing, garments and garment
washing plants.
Some of these plants generate huge amount of wastewater,
which find their way into the environment.
These wastewaters are polluted and may cause various
types of consequences and complicacies.
7/30/2019 MSC Presentation 1312
3/23
Many factories have already installed Effluent Treatment Plants
(ETP).
Lot of ETPs are in various stages of their commissioning /operation.
Setting up of ETP does not and will not always ensure a safe
environment.
It is a collective and social responsibility to monitor and ensure cleanenvironment.
In order to make it a collective issue it will be necessary to make
awareness about the harmfulness of environmental pollution.It is also important to know the characteristics of effluent generated
by various types of textile processes and plants.
7/30/2019 MSC Presentation 1312
4/23
Sl.
No.
Water quality
parameters
Unit Standard value for discharging into *
Inland river On land for
irrigation
1 PH ---- 6-9 6-9
2 BOD mg/L
7/30/2019 MSC Presentation 1312
5/23
Name of the factory Type of thefactory
/plantConcentration of pollutants present in the wastewater
BODmg/L COD
mg/LTD
Smg/L
TSS
mg/LOil &
Greasemg/L
ColourCo-pt. Temp0C PH
1 2 3 4 5 6 7 8 9 10Ahsan Composite Knit
dyeing 300 437 2210 82 ND* ND ND 9.39Reedisha Knitex Ltd. Knit
dyeing 300 449 3380 3118 ND ND ND 9.01Fakhruddin Textile Mills
LtdKnit
dyeing
450 1000 3500
100 ND Dark ND 9-11Grameen knitwear Knit
dyeing
600 1200 - 1000 10 Dark ND 10Southeast Knit
dyeing
450 1000 3500 100 --- Dark ND 11
Epyllion Knit Ltd. Knitdyeing 450 1400 3500 200 60 600 60 9
Aboni Textiles Ltd. Knitdyeing 350 1050 3500 200 40 140 35 11
Greenland garments ltd. Knitdyeing 450 1000 4500 100 ND Dark ND 6-9
Ha-Meem Denim Denim 850 2150 - 350 20
7/30/2019 MSC Presentation 1312
6/23
Table-2: Characteristics generated by various textile
processs
7/30/2019 MSC Presentation 1312
7/23
Effect of pH of the effluent
Table 3: Comparison of pH with Bangladesh standard.Name of the
factory Type of the
factory/plant
pH Standard value for discharging intoInland river On land for
irrigation
1 2 3 4 6Ahsan Composite Knit dyeing 9.39 6-9 6-9Southeast Knit dyeing 11 6-9 6-9
Ha-Meem Denim
Denim
9
6-9
6-9
Jamuna denim Denim 11 6-9 6-9
Various standards suggest that pH greater than 9.5 or less than 4.5 areunsuitable for most aquatic organisms.
7/30/2019 MSC Presentation 1312
8/23
Effect of pH on aquatic life
All submerged plants and animals, are constantly removing dissolved
oxygen from the water and excreting carbon dioxide during normal
respiration.
During daylight hours all plants, which include all algal forms, actively
involve in photosynthesis.
Young fish and immature stages of aquatic insects are extremely sensitiveto pH levels out side (58) and may die beyond these pH values.
High pH levels like (9-14) can harm fish by denaturing cellular
membranes.
Rapid changes in pH are stressful to fish and should be avoided.
Changing the pH by more than 3 units per day is known to stress fish.
7/30/2019 MSC Presentation 1312
9/23
Biochemical Oxygen demand (BOD):
The amount of Dissolved oxygen (DO) required to degrade organic matters
of certain wastewater is regarded as Biochemical Oxygen Demand (BOD).
It is measured as ppm or mg/lMicroorganisms such as bacteria are responsible for decomposing organic
waste.
When organic matter such as dead plants, leaves, grass clippings, cellulose
components, manure, sewage, organic waste like dyes, fats and oils, or even
food waste is present in a body of water, the bacteria will begin the process
of breaking down this waste.
In degrading the organic waste, the bacteria rob the available dissolved
oxygen necessary to survive by the other aquatic organisms like fishes and
aquatic insects.
7/30/2019 MSC Presentation 1312
10/23
BOD (Contd)
The higher the organic waste the higher will be the number of
bacteria to degrade. Higher will be the oxygen consumption.Under this circumstance there will be an additional demand fordissolved oxygen (DO).
This additional demand for DO is regarded as BOD.
As the waste is consumed gradually or dispersed through the water,
BOD levels will begin to decline.Table 3: Comparison of (BOD) with Bangladesh standard.Name of the factory Type of the
factory /plant BODmg/
L
Standard value for discharging intoInland river
(mg/L) On land for
irrigation (mg/L)
1 2 3 4 6Ahsan Composite Knit dyeing 300
7/30/2019 MSC Presentation 1312
11/23
BOD (Cont..)
The presence of Nitrogen and phosphates in a body of water can also
contribute to high BOD levels.
Nitrates and phosphates are plant nutrients and can cause plant life and
algae to grow quickly.
When plants grow quickly, they also die quickly.
This contributes to the organic waste in the water, which is then
decomposed by bacteria. This also results in a high BOD level.
The temperature of the water can also contribute to high BOD levels.
Warmer water usually will have a higher BOD level than colder water.
As water temperature increases, the rate of photosynthesis by algae and
other plant life in the water also increases.
Therefore, increased water temperatures will speed up bacterial
decomposition and result in higher BOD levels.
7/30/2019 MSC Presentation 1312
12/23
Table-4: Sizing ingredients used for various types of denim fabricsQuality Water
(Litre) Starch(Kg) PVA(Kg) Size CA(Kg) Wax(Kg)7R,9K
410
40
7
6
4
7Rs 400 40 7 7 512Rs + K 400 40 8 7 420Rs 380 40 10 7 510Rs 400 40 10 7 430 Rs + K 380 40 10 7 5BOD and DO (Dissolved oxygen)The amounts of oxygen present in a certain amount of water in dissolved
state are known as Dissolved Oxygen or simply DO.
DO is normally expressed as mg/l, and varies from 0 to 18 mg/l
In most cases of normal waters, DO lies between 7-9 mg/l.
7/30/2019 MSC Presentation 1312
13/23
Chemical Oxygen Demand (COD):The organic compounds of the textile dyes and auxiliaries may be
oxidized by means of the dissolved oxygen present in the water
As a result the level of DO falls and there will be demand for oxygen,which is termed as Chemical Oxygen Demand (COD).COD accounts for all oxidisable organic compounds while, BOD refers
to only biodegradable organics.
Table 5: Comparison of COD with Bangladesh standard.Name of the factory Type of the
factory
/plantCODMg/L
Standard value for discharging intoInland river
(mg/L) On land forirrigation(mg/L)
1 2 3 4 6Ahsan Composite Knit dyeing 437
7/30/2019 MSC Presentation 1312
14/23
Table 9: COD of some selected dyes
Dye Structure COD (g O2)/g of dyeVat Blue 4 Anthraquinone 1600Vat green 1 Anthraquinone 1800
Direct Blue 199 Phtalocynanine 700Disperse Blue 56 Anthraquinone 1500
Reactive Blue 204 Oxazine (MFT) 650Reactive Blue-209 Formazan (FCP) 800
Sulfur ----- 650
7/30/2019 MSC Presentation 1312
15/23
Total suspended Solids (TSS):
TSS is mainly organic in nature, is visible and can be removed from the
wastewater by physical/ mechanical means e.g. screening and
sedimentation.
The pore size of the filter paper is very important in estimating the TSS,
the nominal pore size 1.58 micro metre.Table 6: Comparison of TSS with Bangladesh standard.Name of the factory Type of the
factory
/plantTSSMg/l
Standard value for discharging intoInland river
(mg/l) On land forirrigation (mg/l)1 2 3 4 6
Ahsan Composite Knit dyeing 82
7/30/2019 MSC Presentation 1312
16/23
Total Dissolved Solids (TDS):
TDS -is the sum total of all of the dissolved things in a given body of
water.
Hardness, alkalinity, cyanuric acid, potassium, chlorides and sodium,bromides, sulfates, silicates, and all manner of organic compounds.
Textile effluent inherits TDS from dyes, chemicals and auxiliaries that are
used in processing.
Table 7: Comparison of TDS with Bangladesh standard.Name of the factory Type of the
factory
/plantTDSMg/L
Standard value for discharging intoInland river
(mg/L) On land forirrigation(mg/L)
1 2 3 4 6Ahsan Composite Knit dyeing 2210
7/30/2019 MSC Presentation 1312
17/23
Dyes and the Environment:Dyes are present in the effluent at concentrations of 10 mg/l to 50 mg/l
with 1 mg/l being visible to the naked eye.
Photochemical reactions may be important, as dyes are good absorbers of
solar energy.
Aquatic plants will not be able to produce food by the process of
photosynthesis. As a result their life will be endangered.Table-8: Comparison of Color point with Bangladesh standard.Name of the factory Type of the
factory
/plantColourCo.pt
Standard value for discharging intoInland river
(Co.pt) On land forirrigation(Co.pt)1 2 3 4 6
Grameen knitwear Knit dyeing Dark
7/30/2019 MSC Presentation 1312
18/23
Table 5: Typical fixation of various dyes (Source-www.e-textile.org)
7/30/2019 MSC Presentation 1312
19/23
Effect of temperature on Environment:Temperature controls the rate of metabolic and reproductive activities, and
determines which aquatic species can survive.
Different aquatic species require different quantity of DO to survive in the
water.
Temperature inversely affects the rate of transfer of gaseous oxygen into
dissolved oxygen.
At higher temperature the metabolic rate of aquatic plants and animals
increases producing an increase in oxygen demand.
Related International regulations classifies water, as "Class 1 Cold Water
Aquatic Life" max. temp. 20C, as "Class 2 Warm Water Aquatic Life"
max temp. 30C.
Generally, a max. 3 C increase over a minimum of a 4-hr period, lasting
12 hrs maximum, is deemed acceptable.
(C td ) Eff t f t t
7/30/2019 MSC Presentation 1312
20/23
(Contd) Effect of temperature
Respiration rates can increase by 10% or more per 1 C temperature rise.
Increase in temp. of textile wastewater reduces oxygen availability, and
increases oxygen demand.The onsite test shows that effluent temperature is around 50-600C which is
quite harmful for aquatic species.Oil and greases
The term oil and grease, as commonly used, includes the fat, oils, waxes,
and other related constituents found in wastewater.
Oils and fats are mainly due to the sizing process and also as oils and
grease comes in contact with the fabric during processing. Small amountoils is found in the cellulose fibres.
Oils and fats form a layer at the top surface of the wastewater. As a result
the oxygen cannot come in contact with the water and becomes difficult to
increase DO level.
OIL & G
7/30/2019 MSC Presentation 1312
21/23
OIL & Grease
Research show that oil is toxic to fish. In greater quantities, it limits
oxygen transfer, hindering biological activity.
Oils and grease affect respiration of fish by adhering to the gills, it adhereto and destroy algae and plankton.
Feeding and reproduction of water life are affected by oils and fat.Table 7: Comparison of oil and grease with Bangladesh standard.Name of the factory Type of the
factory /plant Oil andgrease(mg/l)
Standard value for discharging
Inland river
(mg/L) On landforirrigation
1 2 3 4 6Grameen knitwear Knit dyeing 10 < 10 < 10Epyllion Knit Ltd. Knit dyeing 60 < 10 < 10Ha-Meem Denim Denim 20 < 10 < 10Partex denims Denim ND < 10 < 10
7/30/2019 MSC Presentation 1312
22/23
CONCLUSION/SUGGESTIONSProper management of wastewater will reduce the overall volume of
effluent.
All the factories should install and run ETP.
Setting up industries far away from the crowded greater Dhaka will
at least reduce the pollution burden on the Dhaka dwellers to some
extent.
Starch based sizes should be replaced with synthetic sizes.Government should reduce or exempt the tariffs and taxes on the
synthetic sizes.
Reconstitution of processed effluent should be examined.
CONCLUSION/SUGGESTIONS (C td )
7/30/2019 MSC Presentation 1312
23/23
CONCLUSION/SUGGESTIONS (Contd._)Attempt should be made to expand woven sector. Woven account for
less m:l ratio, less energy higher profit. In knit the m:l ratio is nearly
1:200.
Selection of dyes, chemicals and auxiliaries that generate lower
pollutants will reduce ultimate pollution load.
Like many developed countries, Government can offer free water
and wastewater test facilities.
Environment is also violated by slaughtering houses, sweet
manufacturers, bakeries, poultry farms etc.
Research is necessary to study the effect and toxicity of various dyes,
chemicals and auxiliaries used in our country.Research is also necessary to reduce the operating cost of the existing
plants.