The document discusses effluents from the textile industry. It provides details on the various processes in textile manufacturing that generate effluent, the types of pollutants produced at each stage, and typical characteristics of textile industry effluent. The summary is: Textile manufacturing involves several wet processing steps that use large amounts of water and generate highly polluted effluent. Effluent from preparatory, dyeing, printing, and finishing stages contributes to high levels of BOD, COD, suspended solids, and color. Effective treatment is needed to remove pollutants before the effluent is discharged.

2.  Effluent is the stream of excess chemical liquor from
an industry after using in original operation.
 Example:
 The excess dye liquor extracted from the textile
industry after dyeing is an effluent of that dyeing
industry.

3. On an average 100 litres of water is required for dyeing
1kg fabric. 10 lakh litres water per day is required in a
factory with 10 tons production capacity.
In comparison to other industry, textile industry uses
large volume of water and is obviously true and a major
polluter.

4. Unit process Possible pollutants in the waste
water
Nature of the waste water
Desizing Starch, glucose, CMC, PVA,
resin, fats and waxes.
High BOD (35-50% of total)
Scouring NaOH, waxes, greases, Na2CO3
and fragments of cloth.
Strongly alkaline weak color.
High BOD (30% of total)
Bleaching Na(OCl),Cl2, NaOH, H2O2, acid
etc.
Alkaline 5% of total BOD
Mercerisation NaOH Strongly alkaline low BOD
(less than 1%)
Dyeing Various dyes, salts, alkali, acid,
Na2S, Na2S2O4 and soaps,
detergent etc.
Strongly colored fairly BOD
(6% of the total)
Printing Colors, starch, china clay, gum,
oil, mordents, acid, alkali,
various metallic salts etc.
Highly colored and oily
appearance BOD, (6-10% of
total)
Finishing Traces of starch, tallow and
different finishing agents.
Low BOD (2-4% of total)

5. It is a measure of oxygen (O2) required for the living
organism in the water for oxidizing the organic matter (O, C,
N etc.) present in water. The range of BOD in effluent is
250-500 mg/L.
O + O O2
C + O2 CO2
NO + O2 NO2
It is measured by the quantity of oxygen of utilized
by suitable aquatic micro-organisms during five days.

6. This is a measure of the amount of oxygen it will
consume for oxidation of the organic chemical present
in the effluent with a strong oxidation agent such as
potassium dichromate.
Range: 800-1200 mg/L

7. Serial No Characteristics Average quantity
of the effluent
Required limit to
discharge
01 BOD 250-500 mg/L 20-40 mg/L
02 COD 800-1200 mg/L 120-160 mg/L
03 Suspended solid 200-300 mg/L 20-40 mg/L
04 Settle able solid 0-5 mg/L Traces
05 Ammonia 20-30 mg/L 4-8 mg/L
06 Phosphate 3-5 mg/L 3-5 mg/L
07 Surfactant 30-40 mg/L 0.5-2 mg/L
08 Chloride 1000-1500 mg/L 1000-1500 mg/L
09 Sulphate 1000-1500 mg/L 1000-1500 mg/L
10 Color Colored Not perceptible
11 Oil and fat 30-40 mg/L < 5 mg/L
12 Phenol 3-5 mg/L < 0.05 mg/L
13 Temp. 45-0500 C ≥450 C

8. Waste water from textile industry destroys the quality of
water body in which they are exposed affecting the
marine life. It also has harmful effect on sewerages
handling system and agricultural land. The
characteristics and effects of effluents are measured/
summarized as follows:

9. a. PH: The waste water may be either acidic or alkaline.
 FOR HIGH ACIDIC WATER:
I. Corrosion of pipe lines and equipments.
II. Destruction of aquatic life.
 FOR HIGH ALKALINE WATER:
I. Adverse effect on aquatic life.
II. Incrustation sewers and damage to the crops by impairing their
growth.
b. DISSOLVED SOLIDS:
They are both organic and inorganic. They cause reduction in
dissolved oxygen in water causes diseases and discomfort,
scale in pipe lines and equipments, accelerate algal growth,
increase hardness of water and enhance metal corrosion.
c. SUSPENDED SOLIDS:
I. Turbidity
II. Interferes with light transmitting properties of water
III. Destroys photosynthesis and oxygen transfer process

10. Primary filtration
Cooling and Mixing
Neutralisation by
acid/alkali dosing
Chemical coagulation
Primary clarifier
Biological treatment
(Aeration Tank)
Secondary clarifier
Filter/Discharge to drains
Removal of gross solid such as waste,
threads, lint, fabric pieces etc.
Air blowing through blower
Chemical coagulation is very effective for
removal of color and suspended matters.
FeSO4, FeCl3, lime (CaO) + cationic
polymer.
To settle down the flocks setting and
separation of sludge .

11. Air from blower
2
Mixing &
Cooling tank
Pump
FeSO4 + FeCl3 + CaO, cationic polymer
Urea + Diamonium phosphate DHP
The sludge with bacteria brought out back
Discharge
to drainAir from
blower
Sludge
Air from
blower
Sludge pit
Sludge thickener
Bed
Shed
Acid/Alkali
3
1
4
5
6 7
8
1. Primary filtration
2. Cooling & Mixing
3. Neutralization by acid/Alkali dosing
4. Chemical coagulation
5. Primary clarifier
6. Biological treatment
7. Secondary clarifier
8. Filter
Fig: Schematic diagram of ETP

12. 1. Biological
2. Chemical
3. Chemical and Biological (Bio-chemical)
4. Filtration
5. Electrical
6. UV treatment
7. Reverse osmosis

13. Combination of precipitation of insoluble salts,
coagulation of colloidal material and flocculation.
CAO: Neutralised any excess acidity and precipitated
many types of anionic compound.
The aluminum or ferric hydroxide, along with
precipitated aluminum or ferric salt, removes colloidal
matter and no. of anionic dyes.
Sedimentation is assisted by adding a flocculent such as
a poly-acrylic acid derivative or a cationic polymer, the
latter being able to bind hydrolysed reactive dyes.

14.  Textile industry involves wide range of raw materials, machineries
and processes to engineer the required shape and properties of the
final product.
 Waste stream generated in this industry is essentially based on water-
based effluent generated in the various activities of wet processing of
textiles.
 The main cause of generation of this effluent is the use of huge
volume of water either in the actual chemical processing or during
re-processing in preparatory, dyeing, printing and finishing.
 In fact, in a practical estimate, it has been found that 45% material in
preparatory processing, 33% in dyeing and 22% are re-processed in
finishing [Sivaramakrishnan, C.N., 2004.].
 The fact is that the effluent generated in different steps is well
beyond the standard and thus it is highly polluted and dangerous.

15.  Textile waste is broadly classified into four categories, each of
having characteristics that demand different pollution
prevention and treatment approaches.
 Hard to Treat Wastes: It includes those that are persistent, resist
treatment, or interfere with the operation of waste treatment facilities. Non-
biodegradable organic or inorganic materials are the chief sources of wastes,
which contain color, metals, phenols, certain surfactants, toxic organic
compounds, pesticides and phosphates.
 Hazardous or Toxic Wastes: In textiles, hazardous or toxic
wastes include metals, chlorinated solvents, non-biodegradable or volatile
organic materials. Some of these materials often are used for non-process
applications such as machine cleaning.

16.  High Volume Wastes: Large volume of wastes is sometimes a problem for the
textile processing units. Most common large volume wastes include:
 High volume of waste water
 Wash water from preparation and continuous dyeing processes and alkaline wastes from
preparatory processes
 Batch dye waste containing large amounts of salt, acid or alkali
 Dispersible Wastes : The following operations in textile industry generate
highly dispersible waste
 Waste stream from continuous operation (e.g. preparatory, dyeing, printing
and finishing)
 Print paste (printing screen, squeeze and drum cleaning)
 Lint (preparatory, dyeing and washing operations)
 Foam from coating operations
 Solvents from machine cleaning
 Still bottoms from solvent recovery (dry cleaning operation)
 Batch dumps of unused processing (finishing mixes)

17.  Physical Parameters
 Color: The color of water is a physical indicator of purity of surface and
ground waters. It is caused by soluble and insoluble substances. Pure
natural waters are usually colorless or azure-blue in thick layers. It can be
determined by colorimeter in PCU (Platinum cobalt unit) as unit.
 Odor: The odor of water is caused by volatile substances present in water
which are perceived by the sense of smell, particularly living microscopic
organism or decaying vegetation including algae, actinomycetes, bacteria,
fungi and weeds. Sewage and industrial wastes also contribute tastes and
odor to receiving waters.
 Temperature: Temperature is one of the most important parameters for
aquatic environment because almost all the physical, chemical and
biological properties are governed by it.

18.  Taste: The taste of water is influenced by substances
introduced into water naturally or by pollution. Water taste
is markedly influenced by amounts of iron, manganese,
magnesium, calcium, zinc, copper, chlorides, sulphates,
hydrogen carbonates, carbon dioxide, etc.
 Total Dissolved Solids (TDS) : Total dissolved solids
contents of water and waste water is defined as the residue
left upon evaporation at 103°C to 105°C. It is an
aggregated amount of the entire floating, suspended,
settable and dissolved solids present in the water sample.

19.  pH : pH is a term used universally to express the intensity
of the acidic or alkaline condition of solution. It is a
measure of hydrogen ion concentration or more precisely
the hydrogen ion activity. It is defined as the " logarithm
(base 10) of the reciprocal of the hydrogen ion
concentration” .
 Electrical Conductivity (EC): Electrical conductivity is
a measure of water capacity to convey electric current.
Electrical conductivity of water and wastewater are
directly proportional to its dissolved matter content
(dissolved gases also contribute). The unit of conductivity
is µS/cm.

20.  Hardness: Hardness is seemed to be the capacity of water for
reducing and destroying the lather of soap. Hardness is caused due to
divalent cations such as Ca+2, Sr+2 etc. Higher cations also contribute
hardness to a lesser degree but mono-valent cations never produce
hardness.
 Alkalinity: Alkalinity is an anionic phenomenon. It is the
quantitative capacity of an aqueous media to react with hydrogen
ions. The occurrence of hydrogen ion in natural water is very rare,
unless artificial contamination has occurred.
 Dissolved Oxygen (DO): Dissolved oxygen shows the ability of the
stream to purify itself through biochemical process. Oxygen is
dissolved in most waters in varying concentrations. Solubility of
oxygen depends on temperature, pressure and salinity of water. It is
essential to life of fish and other aquatic organisms.

21.  Bio-chemical Oxygen Demand (BOD): Bio-chemical
oxygen demand tests show the amount of molecular
oxygen required by bacteria to reduce the carbonaceous
materials and transformation of organic matter under
aerobic conditions. It is a test of great value in the analysis
of sewage, industrial effluents and grossly polluted waters.
 It is a bioassay procedure that measures the oxygen
consumed by living organisms, while utilizing the organic
matter.
 The determination of DO of a sample before and after five
days incubation at 20°C is the basic of BOD
determination.

22.  Chemical Oxygen Demand (COD): American Society for
Testing and Materials (ASTM) defines chemical oxygen
demand as the amount of oxygen, expressed in mg/l
consumed under specific conditions in the oxidation of
organic and oxidizable inorganic matter, corrected for the
influence of chlorides.
 COD test shows the oxygen equivalent of the organic
matter that can be oxidized by using a strong oxidizing
agents e.g. potassium dichromate in acidic solution, at
elevated temperature, for two and half hour.
 It has to be classified that COD is not a measure of the
carbon content. It indicates the amount of oxygen required
to oxidize the carbonaceous matter.