Two types of waste are generated from textile processing: process chemicals and fiber wastes. The nature of the waste depends on the type of textile facility, processes used, fibers, and chemicals. Textile effluent can include dispersible wastes mixed with other wastes in wastewater, hard-to-treat wastes that resist treatment and contain non-biodegradable or inorganic materials, and high-volume wastes like wash water, alkaline wastes, and warp sizes. Effluent can also contain hazardous or toxic wastes like metals, chlorinated solvents, and non-degradable surfactants. Common treatment processes include screening, sedimentation, equalization, neutralization, chemical

1. TEXTILE EFFLUENT TREATMENT
CHAPTER THREE
Granch Berhe

2. EFFLUENTS DISCHARGED BY TEXTILE
PROCESSING INDUSTRY
3.1

3. Total Textile Process at a Glance
Two types of waste are generated: process chemicals and fiber wastes
The nature of the waste generated depends on
 Type of textile facility
Processes and technologies
 Types of fibers and chemicals

4. 09/03/15 4

5. 09/03/15 5

6. Dispersible wastes
Highly dispersed or mixed with other wastes: Waste water
Hard-To-Treat Wastes
Resist treatment
Contain non biodegradable or inorganic
Cannot be removed by biological processes
High- Volume Wastes
High-volume wastes in textiles include wash water, alkaline
wastes, warp sizes
Hazardous or Toxic Wastes
Subgroup of hard-to-treat wastes.
Metals, chlorinated solvents, non degradable surfactants
Dispersible wastes
Highly dispersed or mixed with other wastes: Waste water
Hard-To-Treat Wastes
Resist treatment
Contain non biodegradable or inorganic
Cannot be removed by biological processes
High- Volume Wastes
High-volume wastes in textiles include wash water, alkaline
wastes, warp sizes
Hazardous or Toxic Wastes
Subgroup of hard-to-treat wastes.
Metals, chlorinated solvents, non degradable surfactants
6
General Waste Categorization

7. Acute ToxicityAcute Toxicity
Single or multiple exposures in a short space of time (usually less than 24
hours).
Acute Toxicity of Textile Dyes
Skin Irritation
Vomit
Diarrhea
Reactive dyes can cause respiratory or skin sensitisation problems in
plant workers who manufacture the dyes and textile workers
Reactive Dyes + Human Serum Albumin [HSA]
Dye-HSA conjugate, which acts as an antigen. The antigen produces
specific immunoglobulin E (IgE) and, through the release of chemicals
such as histamine, causes allergic reactions
Single or multiple exposures in a short space of time (usually less than 24
hours).
Acute Toxicity of Textile Dyes
Skin Irritation
Vomit
Diarrhea
Reactive dyes can cause respiratory or skin sensitisation problems in
plant workers who manufacture the dyes and textile workers
Reactive Dyes + Human Serum Albumin [HSA]
Dye-HSA conjugate, which acts as an antigen. The antigen produces
specific immunoglobulin E (IgE) and, through the release of chemicals
such as histamine, causes allergic reactions
7
ToxicityToxicity

8. Chronic Toxicity
Non Genotoxicity
1.Water solubility
Water-soluble molecules are generally excreted rapidly by
a living organism
2.Water Insolubility
Due to the insolubility, toxicants gets large size particles
[0.1 to 3 mm] in the body which are not transported across
cell membranes.[e.g.] Pigments

9. Genotoxicity
 Mutagens
 Carcinogens
 Teratogens
 Toxicants reach the DNA (which resides in the nucleus of the
cell) in order for the chemical to interact with the DNA.
 So the toxicants will be able to transport across the protective
cell membranes
 Active species of most carcinogens, known as the ultimate
carcinogen, is an electrophile,
 E.Nitrenium ion [R2N+]
 Carbonium ion [R3C+]
 Carcinogens attack a nucleophilic site in DNA, which may
be a carbon, nitrogen or oxygen atom, to form a covalent
chemical bond E + [DNA] or E–[DNA]
Genotoxicity
 Mutagens
 Carcinogens
 Teratogens
 Toxicants reach the DNA (which resides in the nucleus of the
cell) in order for the chemical to interact with the DNA.
 So the toxicants will be able to transport across the protective
cell membranes
 Active species of most carcinogens, known as the ultimate
carcinogen, is an electrophile,
 E.Nitrenium ion [R2N+]
 Carbonium ion [R3C+]
 Carcinogens attack a nucleophilic site in DNA, which may
be a carbon, nitrogen or oxygen atom, to form a covalent
chemical bond E + [DNA] or E–[DNA] 9

10.  The toxic effects of the azo dyes may result from the
direct action of the agent itself or of the aryl amine
derivatives generated during reductive biotransformation
of the azo bond.
 The azo dyes entering the body by ingestion can be
metabolized to aromatic amines by the azoreductases of
intestinal microorganisms.
 If the dyes are nitro, they can be metabolized by the
nitroredutases produced by the same microorganisms.
 Mammalian liver enzymes and other organizations may
also catalyze the reductive cleavage of the azo bond and
the nitro reduction of the nitro group.
 In both cases, if N-hydroxylamines are formed, these
compounds are capable of causing DNA damage.
 The toxic effects of the azo dyes may result from the
direct action of the agent itself or of the aryl amine
derivatives generated during reductive biotransformation
of the azo bond.
 The azo dyes entering the body by ingestion can be
metabolized to aromatic amines by the azoreductases of
intestinal microorganisms.
 If the dyes are nitro, they can be metabolized by the
nitroredutases produced by the same microorganisms.
 Mammalian liver enzymes and other organizations may
also catalyze the reductive cleavage of the azo bond and
the nitro reduction of the nitro group.
 In both cases, if N-hydroxylamines are formed, these
compounds are capable of causing DNA damage.

11.  Moreover, the reduction of azo dyes by sodium
hydrosulfite and the successive chlorination steps with
hypochlorous acid, can form 2-benzotriazoles
phenilbenzotriazol (PBTA) derivatives and highly
mutagenic aromatic amines, often more mutagenic than
the original dye.
 Effects caused by other pollutants in textile wastewater,
and the presence of very small amounts of dyes (<1
mg/L for some dyes) in the water, which are
nevertheless highly visible, seriously affects the
aesthetic quality and transparency of water bodies
 Moreover, the reduction of azo dyes by sodium
hydrosulfite and the successive chlorination steps with
hypochlorous acid, can form 2-benzotriazoles
phenilbenzotriazol (PBTA) derivatives and highly
mutagenic aromatic amines, often more mutagenic than
the original dye.
 Effects caused by other pollutants in textile wastewater,
and the presence of very small amounts of dyes (<1
mg/L for some dyes) in the water, which are
nevertheless highly visible, seriously affects the
aesthetic quality and transparency of water bodies
11

12.  Anthraquinone dyes of the solvent or disperse class
containing one or more primary amino- or methyl amino-
groups tend to be mutagenic or carcinogenic.
 Cations bind to sulfhydryl (-SH) group (cysteine amino
acid) in enzymes disrupting the vital metabolic reaction
catalyzed by the enzyme.
 The high alkalinity and traces of chromium (employed in
dyes) adversely affect the aquatic life.
 Imidazole is corrosive to skin and irritating to eyes in
rabbits--may cause permanent eye injury, teratogenicity and
developmental toxicity observed at doses maternally toxic
in rats.
 Chloroflorocarbon based chemicals like FR causes ozone
layer depletion
 Anthraquinone dyes of the solvent or disperse class
containing one or more primary amino- or methyl amino-
groups tend to be mutagenic or carcinogenic.
 Cations bind to sulfhydryl (-SH) group (cysteine amino
acid) in enzymes disrupting the vital metabolic reaction
catalyzed by the enzyme.
 The high alkalinity and traces of chromium (employed in
dyes) adversely affect the aquatic life.
 Imidazole is corrosive to skin and irritating to eyes in
rabbits--may cause permanent eye injury, teratogenicity and
developmental toxicity observed at doses maternally toxic
in rats.
 Chloroflorocarbon based chemicals like FR causes ozone
layer depletion 12

13.  Formaldehyde, a highly toxic, colourless gas, has been linked to
skin irritation and allergic reactions. Even more worryingly, the
chemical is classified as a human carcinogen
 Sulphur dye cause even acid rain
Other worse Effects
Brain function, decreased attention, retardation
Reproduction including miscarriage, until births
Most sensitive are children <7; immature blood-brain barrier;
effects mental development etc……
 Formaldehyde, a highly toxic, colourless gas, has been linked to
skin irritation and allergic reactions. Even more worryingly, the
chemical is classified as a human carcinogen
 Sulphur dye cause even acid rain
Other worse Effects
Brain function, decreased attention, retardation
Reproduction including miscarriage, until births
Most sensitive are children <7; immature blood-brain barrier;
effects mental development etc……
 Carcinogenic substances: 59 substances.
 Mutagenic substances: 9 substances .
 Substances toxic to reproduction: 39 substances.
 Allergenic substances:14 substances with respiratory sensitization 56
substances with skin sensitization properties.
 Substances with environmentally hazardous, long-term effects:
approximately 57 substances.
 Carcinogenic substances: 59 substances.
 Mutagenic substances: 9 substances .
 Substances toxic to reproduction: 39 substances.
 Allergenic substances:14 substances with respiratory sensitization 56
substances with skin sensitization properties.
 Substances with environmentally hazardous, long-term effects:
approximately 57 substances.

14. 14
Carcinogenic aromatic amidesCarcinogenic aromatic amides

15. 1. Organic chlorine carriers (dyed acceleration)
2. Separation of chlorine bleach materials, except the sodium
chlorite from the bleached synthetic fibers
3. The free chlorine after using sodium chlorite
4. Arsenic, mercury and their mixtures
5. Alkyl phenol as a bleaching agent
6. Cr6 + compounds in the oxidizing of sulfur dyes and vat dyes
7. EDTA, DTPA, and phosphate in the water treatment softeners
8. Formadehyde based chemicals and gases
9. Chloroflorocarbon based chemicals and gases
10. Aryl and aromatic amide components
11. Accumulation of chemicals dyes and textile auxiliaries
1. Organic chlorine carriers (dyed acceleration)
2. Separation of chlorine bleach materials, except the sodium
chlorite from the bleached synthetic fibers
3. The free chlorine after using sodium chlorite
4. Arsenic, mercury and their mixtures
5. Alkyl phenol as a bleaching agent
6. Cr6 + compounds in the oxidizing of sulfur dyes and vat dyes
7. EDTA, DTPA, and phosphate in the water treatment softeners
8. Formadehyde based chemicals and gases
9. Chloroflorocarbon based chemicals and gases
10. Aryl and aromatic amide components
11. Accumulation of chemicals dyes and textile auxiliaries
15
The following must not be in the wastewaterThe following must not be in the wastewater

16. TREATMENT PROCEDURE PARAMETERS
OF WET PROCESSING OPERATIONS
3.2

17. WASTE WATER FROM DIFFERENT PROCESS

18. COD
BOD
High pH
Wet process Industrial
effluents
SUSPENDED
SOLIDS
GASES/CHLORINE,
CO2,O2Strong color
Heavy metals/ iron, magnesium, arsenic, copper
SALTS/chlorides,
sulphate, nitrate
09/03/15 18

19. In most cases BOD/COD ratio of the composite textile
wastewater is around 0.25 .This implies that the wastewater
contains large amount of nonbiodegradable organic matter.

20. CLASSIFICATION OF WASTE WATER TREATMENT PROCESS

21. Remove organic color, suspended solids
Helps in primary reduction of COD & BOD
PRIMARY SCREENING
SEDIMENTATION
EQUALIZATION
NEUTRALIZATION
CHEMICAL
COGULATION
MECHNICAL
FLOCCULATION
 The conventional treatment
systems is a Physico-chemical
treatment followed by biological
treatment (Secondary) system
3.2.1

22. Purpose: to remove coarse suspended matters such as rags, pieces of fabric, fibers,
yarns .
bar screens and mechanically cleaned fine screens remove most of the fibers
Purpose: to remove coarse suspended matters such as rags, pieces of fabric, fibers,
yarns .
bar screens and mechanically cleaned fine screens remove most of the fibers
09/03/15 22
SCREENING

23. SEDIMENTATION
 The fine suspended matter passed through the screens
can be removed efficiently and economically by
sedimentation.
 This process is particularly useful for treatment of wastes
containing high percentage of settable solids
 The sedimentation tanks are designed to enable smaller
particles to settle under gravity.
 The settled sludge is removed from the sedimentation
tanks by mechanical scrapping into hoppers and
pumping it out subsequently.
 Sedimentation is sometimes combined with equalization
operation.
 The fine suspended matter passed through the screens
can be removed efficiently and economically by
sedimentation.
 This process is particularly useful for treatment of wastes
containing high percentage of settable solids
 The sedimentation tanks are designed to enable smaller
particles to settle under gravity.
 The settled sludge is removed from the sedimentation
tanks by mechanical scrapping into hoppers and
pumping it out subsequently.
 Sedimentation is sometimes combined with equalization
operation.
09/03/15 23

24. EQUALIZATION
Effluent streams are collected
into ‘sump pit’ (big tank).
The mixed effluents are stirred
by rotating agitators or by
blowing compressed air from
below.
The pit has a conical bottom for
enhancing the settling of solid
particles.
Effluent streams are collected
into ‘sump pit’ (big tank).
The mixed effluents are stirred
by rotating agitators or by
blowing compressed air from
below.
The pit has a conical bottom for
enhancing the settling of solid
particles.
09/03/15 24
 The textile effluents are highly variable in terms of pH and extent of impurities
 Such individual process effluents from individual processes will severely affect
the secondary treatment processes of effluent treatment.
 It is therefore, necessary to mix the discharges from different processes.
 The textile effluents are highly variable in terms of pH and extent of impurities
 Such individual process effluents from individual processes will severely affect
the secondary treatment processes of effluent treatment.
 It is therefore, necessary to mix the discharges from different processes.

25. NEUTRALISATION
 Normally, ph values of cotton
finishing effluents are on the
alkaline side.
 Hence, ph value of equalized
effluent should be adjusted.
 Use of dilute sulphuric acid
and boiler flue gas rich in
carbon dioxide are commonly
used .
 Since most of the secondary
biological treatments are
effective in the ph 5 to 9,
neutralization step is an
important process to facilitate
these processes
 Normally, ph values of cotton
finishing effluents are on the
alkaline side.
 Hence, ph value of equalized
effluent should be adjusted.
 Use of dilute sulphuric acid
and boiler flue gas rich in
carbon dioxide are commonly
used .
 Since most of the secondary
biological treatments are
effective in the ph 5 to 9,
neutralization step is an
important process to facilitate
these processes
USUALLY H₂SO₄ 1 gm/m³ TO BRING
PH 8.5.09/03/15 25

26. CHEMICAL COAGULATION/MECHANICAL FLOCUALTION
 Finely divided suspended solids
and colloidal particles cannot
be efficiently removed by
simple sedimentation by
gravity.
 In such cases, mechanical
flocculation or chemical
coagulation is employed.
 In mechanical flocculation, the
textile waste water is passed
through a tank under gentle
stirring;
 The finely divided suspended
solids coalesce into larger
particles and settle out.
 Specialized equipment such as
clariflocculator is also available,
wherein flocculation chamber
is a part of a sedimentation
tank.
 Finely divided suspended solids
and colloidal particles cannot
be efficiently removed by
simple sedimentation by
gravity.
 In such cases, mechanical
flocculation or chemical
coagulation is employed.
 In mechanical flocculation, the
textile waste water is passed
through a tank under gentle
stirring;
 The finely divided suspended
solids coalesce into larger
particles and settle out.
 Specialized equipment such as
clariflocculator is also available,
wherein flocculation chamber
is a part of a sedimentation
tank.09/03/15 26

27. SECONDARY
AERATED LAGOON
TRICKLING FILTRATION
ACTIVATED SLUDGE
PROCESS
OXIDATION DITCH /POND
The main purpose of secondary treatment is to provide BOD removal beyond what is
achievable by simple sedimentation.
Remove dissolved and
residual organic matter
aerobic mode (with air
CO2 &CH4) or with
anaerobic mode.
Achieved by digestive
action of bacteria under
suitable conditions (PH 6-
9,nuetrents,air/oxygen and
temperature
Reduce COD, BOD
and toxicity.
In such cases, the recent
trend is to set up an
activated adsorption
system or and ozonation
unit instead of biological
treatment process.3.2.2

28. AERATED LAGOON
09/03/15 28
 The effluents from primary treatment processes are collected in tanks and are aerated
 Air is blown in the form of stream of bubbles at the bottom with mechanical devices, for
about 2 to 6 days.
 During this time, a healthy flocculent sludge is formed which brings about oxidation of the
dissolved organic matter.
 BOD removal to the extent of 99% could be achieved with efficient operation.
 The effluents from primary treatment processes are collected in tanks and are aerated
 Air is blown in the form of stream of bubbles at the bottom with mechanical devices, for
about 2 to 6 days.
 During this time, a healthy flocculent sludge is formed which brings about oxidation of the
dissolved organic matter.
 BOD removal to the extent of 99% could be achieved with efficient operation.

29. TRICKLING FILTERS
09/03/15 29
 Usually consists of circular or
rectangular beds made of well-graded
gravels media where micro-organisms
deposited on i.e small stone, PVC, coal,
synthetic resins of size 40 mm to 150 mm,
over which wastewater is sprinkled
uniformly on the entire bed with the help
of a slowly rotating distributor (such as
rotary sprinkler).
 Thus, the waste water trickles through
the media.
 The filter is arranged in such a fashion
that air can enter at the bottom; counter
current to the effluent flow and a
natural draft is produced.
 Gelatinous film, comprising of bacteria
and aerobic microorganisms known as
“zooglea”, is formed on the surface of the
filter medium, which thrive on the
nutrients supplied by the wastewater.
 Usually consists of circular or
rectangular beds made of well-graded
gravels media where micro-organisms
deposited on i.e small stone, PVC, coal,
synthetic resins of size 40 mm to 150 mm,
over which wastewater is sprinkled
uniformly on the entire bed with the help
of a slowly rotating distributor (such as
rotary sprinkler).
 Thus, the waste water trickles through
the media.
 The filter is arranged in such a fashion
that air can enter at the bottom; counter
current to the effluent flow and a
natural draft is produced.
 Gelatinous film, comprising of bacteria
and aerobic microorganisms known as
“zooglea”, is formed on the surface of the
filter medium, which thrive on the
nutrients supplied by the wastewater.

30. ACTIVATED SLUDGE PROCESS
09/03/15 30
 This is the most versatile biological
oxidation method employed for
the treatment of waste water
 In this process, the waste water is
aerated in a reaction tank in which
some microbial floc is suspended.
 The aerobic bacterial flora bring
about biological degradation of the
waste into carbon dioxide and
water molecule,
 While consuming some organic
matter bacteria grow
 The bacteria flora grows and
remains suspended in the form of a
floc, which is called “activated
sludge”.
 The effluent from the reaction tank
is separated from the sludge by
settling and discharged.

31.  A part of the sludge is recycled to the same tank to provide an
effective microbial population for a fresh treatment cycle.
 The surplus sludge is digested in a sludge digester, along with
the primary sludge obtained from primary sedimentation.
 An efficient aeration for 5 to 24 hours is required for industrial
wastes.
 BOD removal to the extent of 90-95% can be achieved in this
process.
 Biological effluent treatment processes meets the standards of
BOD,COD, and are suitable for discharge into river, lake or sea.
 However, these treatments are not suitable for removal of
inorganic impurities like salt which are present in the form of
tds.
 Biologically treated water is also not suitable for recycling.
 A part of the sludge is recycled to the same tank to provide an
effective microbial population for a fresh treatment cycle.
 The surplus sludge is digested in a sludge digester, along with
the primary sludge obtained from primary sedimentation.
 An efficient aeration for 5 to 24 hours is required for industrial
wastes.
 BOD removal to the extent of 90-95% can be achieved in this
process.
 Biological effluent treatment processes meets the standards of
BOD,COD, and are suitable for discharge into river, lake or sea.
 However, these treatments are not suitable for removal of
inorganic impurities like salt which are present in the form of
tds.
 Biologically treated water is also not suitable for recycling.
09/03/15 31

32. OXIDATION DITCH /OXIDATION
POND
09/03/15 32
Pond aeration or lake aeration Increase in the oxygen saturation of the water.
Dissolved oxygen (DO) Fish and other aquatic animals and Aerobic bacteria
Pond bottoms of organic soils demand larger amounts of oxygen.

33. TERTIARY OXIDATION TECHNIQUE
ELECTROLYTIC
PRECIPITATION & FOAM
FRACTIONATION
MEMBRANE
TECHNOLOGIES
ELECTROCHEMICAL
PROCESSES
ION EXCHANGE
PHOTO CATALYTIC
DEGRADATION
ADSORPTION
THERMAL EVAPORATION
Remove dissolved solids (mineral salts) and
residual color and odor
After the treatment water can be safely
discharged or reused for processing
In order to reduce TDS further purification of
effluent is carried out using tertiary
treatments
Membrane filtration techniques particularly
RO has become popular due possibility of
recycling treated water
Membrane filtration techniques particularly
RO has become popular due possibility of
recycling treated water
3.2.3

34. ADSORPTION
 The most commonly used method of dye removal by adsorption.
 The process also removes toxic chemicals such as pesticides,
phenols, cyanides and organic dyes.
 Adsorbent for treatment is activated carbon.
 It is manufactured from carbonaceous material such as wood, coal,
petroleum products etc.
 Others: activated clay, silica, fly ash, (inorganic) and bio-
adsorbents-reactive dyes
• Effective for adsorbing cationic, mordant and acid dyes, and to a
slightly lesser extent, dispersed, direct, vat, pigment and reactive
dyes
• Disadvantage: activated carbon is expensive; it has to be
reactivated, which can result in 10-15% loss of sorbent.

35. Ion exchange process is normally
used for the removal of inorganic
salts and some specific organic
anionic components such as phenol.
All salts are composed of a positive
ion of a base and a negative ion of
an acid.
 Ion exchange materials are capable
of exchanging soluble ions and
cations with electrolyte solutions.
ION EXCHANGE

36.  Removal of bacteria,
salts, sugars, proteins,
particles, dyes, and other
constituents
 The separation of ions
with reverse osmosis is
aided by charged particles.
 Dissolved ions that carry a
charge, such as salts, are
more likely to be removed
by the membrane than
those that are not charged,
such as organics.
MEMBRANE FILTRATION

37. 1.REVERSE OSMOSIS
to pass pure water at fairly high rates and to
reject salts at high pressures through the cellulose
acetate or nylon membrane.
Reverse osmosis can be used as end-of-pipe
treatment and recycling system for effluent.

38. 2.ULTRAFILTRATION
The difference between reverse osmosis and
ultrafiltration is primarily the retention
properties of the membranes.
Reverse osmosis membranes retain all solutes
including salts.
 Ultrafiltration membranes retain only macro
molecules and suspended solids.
• They are pressure driven membrane operations that
use porous membranes for the removal of heavy
metals. The main disadvantage of this process is the
generation of sludge.

39. 3.NANOFILTATION
 Nanofiltartion can be positioned between reverse osmosis and
ultrafiltration.
 This process is used where the high salt rejection of reverse
osmosis is not necessary.
 It is capable of removing hardness elements such as calcium or
magnesium together with bacteria, viruses, and colour.
 It operated on lower pressure than reverse osmosis and
treatment cost is lower than RO.
 Preferred when permeate with TDS but without colour, COD
and hardness is acceptable.
 Nanofiltration membranes are similar to reverse
osmosis membranes in several respects except the
degree of removal of monovalent ions such as chlorides
etc.

40. Filtration Spectrum Of Different Membranes

41. Passing water between two plates with opposite
electrical charges.
The metals attracted to negative charge
Non-metals are attracted to positive charge.
Both types of ions can be removed
Electrodialysis is used on very hard water,
more than 500 mg/L as calcium carbonate.
involves the evaporation of water.
The evaporated water leaves behind all hardness
compounds,
ELECTRODIALYSIS
DISTILLATION

42. ADAVNCED OXIDATION PROCESSES (AOP)
Conventional oxidation treatment have found difficulty to oxidize
dyestuffs and complex structure of organic compounds:
 At low concentration or
 If they are especially refractory to the oxidants.
AOP processes are combination of :
- Ozone (O3),
- Hydrogen peroxide (H2O2) and
- UV radiation, which showed the greatest promise
These oxidants effectively decolorized dyes, however did not remove
COD completely.
The goal of any AOPs design is to generate and use hydroxyl free
radical (HO·) as strong oxidant to destroy compound that can not be
oxidized by conventional oxidant.

43. OZONATION
 Ozone is a powerful oxidant agent for water and wastewater.
 Once dissolved in water, ozone reacts with a great number of
organic compounds in two different ways:
By direct oxidation as molecular ozone or
By indirect reaction through formation of secondary
oxidants like hydroxyl radical.
 The conventional fine bubble contactor is the most widely
ozone generator used because of the high ozone transfer
efficiency (90%) and high performance.
 Results presented by a few researchers revealed that ozone
decolorize all dyes, except nonsoluble disperse and vat dyes
which react slowly and take longer time.
 Colour removal using ozonation from textile wastewater is
depended on dye concentration.

44.  According to Rein (2001), conventional ozonation of organic
compounds does not completely oxidize organics to CO2 and
H2O in many cases.
 Remaining intermediate products in some solution after
oxidation may be as toxic as or even more toxic than initial
compound and UV radiation could complete the oxidation
reaction by supplement the reaction with it.
 O3/UV is the most effective method for decolorizing of dyes
comparing with UV oxidation by UV or ozonation alone.
(Hung-Yee and Ching-Rong (1995))
 O3/UV treatment is recorded to be more effective compared to
ozone alone, in terms of COD removal.
O3/UV

45. H2O2/UV
 Oxidization of the textile wastewater with H2O2 alone has been
found ineffective at both acid and alkali values (Olcay et al.,
1996),
 Under UV radiation, H2O2 are photolyzed to form two hydroxyl
radicals (2OH•) that react with organic contaminants (Crittenden
et al., 1999).
 Nonefficient colour removal at alkaline pH
 Therefore the instantaneous concentration in HO* is lower than
expected.
 Furthermore, the H2O2/UV process is more sensitive to the
scavenging effect of carbonate at higher pH values.

46. O3/H2O2
 The addition of both hydrogen peroxide and ozone to wastewater
accelerates the decomposition of ozone and enhancing production
of the hydroxyl radical.
 At higher pH, even very small concentration of H2O2 will be
dissociated into HO2¯ ions that can initiate the ozone
decomposition more effectively than OH ¯ ion.
 H2O2/O3 treatment of synthetic dye house highly depended on
the pH of the effluent.
 It is documented that it was 74% ozone absorption at pH 11.5
(and 10 mM H2O2) whereas at the same concentration of H2O2
and pH 2.5, ozone absorption was only 1
 Complete decolourization of C.I. Reactive Blue 220 and C.I.
Reactive Yellow 15 using H2O2 /O3 process is achieved in 90 min
(Tanja et al., 2003).

47. O3/H2O2/UV
The addition of H2O2 to the O3/UV process accelerates the
decomposition of ozone, which results in an increased rate of OH•
generation.
Among all AOPs, for dye house wastewater and acetate, polyester
fiber dyeing process effluent; combination of H2O2/O3/UV appeared to
be the most efficient in terms of decolouration.
COD removal efficiency of raw textile wastewater increased from
18% to 27% by using sequential ozonation and H2O2/UV.
In the case of bio-treated textile effluent, a preliminary ozonation step
increased COD removal of the H2O2/UV-C treatment system from 15%
to 62%.
99% COD removal from acetate and polyester fiber dyeing process
effluent in batch mode operation(O3/H2O2/UV in 90 min) was achieved.
In raw textile effluent, TOC removal rate was accelerated from 14%
(H2O2/UV-C) and 17% (O3) to 50%.

48. BENEFITS OF ADVANCE TREATMENT METHODS
 Recover water and salt.
 Low TDS water when used in textile processing minimizes
consumption of sequestering agents.
 Corrosion and scale formation can be minimized
 Efficiency of boiler can be improved
 Reusing Brine in dyeing requires less additional salt.
 Reduce problems relating to disposal of high TDS effluents
IS THERE ANY DISADVANTAGE??
 Unknown oxidation products & Expensive

49. MODEL WASTEWATER
TREATMENT PLANT FOR TEXTILE
MILLS
3.3

50. WHAT IS ETP?
ETP
INFLUENT
TREATMENT
EFFLUENT
SLUDGE
ETP OR EFFLUENT TREATMENT PLANT IS USED TO TREAT THE
INDUSTRIAL WASTE WATER.
INFLUENT: UNTREATED INDUSTRIAL WASTE WATER.
EFFLUENT: TREATED INDUSTRIAL WASTE WATER.
SLUDGE: SOLID PART SEPARATED FROM WASTE WATER BY ETP.

51. EFFLUENT TREATMENT PLANT OF DELTA KNIT COMPOSITE LTD
DELTA KNIT COMPOSITE LTD
3.3.1

53. SCREENING
DRUM SCREENER
 SCREENING IS THE
FILTRATION PROCESS FOR THE
SEPARATION OF COARSE
PARTICLES FROM INFLUENT.
 STAINLESS STEEL NET IS USED
FOR SCREENING.
 HARD PLASTIC BRUSHES ARE
USED TO CLEAN THE NET, WHICH
ARE DRIVEN MECHANICALLY.
(DRUM SCREENER IS USED IN THIS ETP)

54. SCHEMTIC DIAGRAM OF DRUM SCREENER

55. EQUALIZATION
EQUALIZATION IS THE PROCESS TO MAKE
THE WASTE WATER-
-HOMOGENOUS &
-COOL
EQUALIZATION TANK IS ALSO CALLED
HOMOGENOUS TANK.
EQUALIZATION TANK
INFLUENT FROM
SCREENING
SPRAY OF WATER COMING
FROM DYEING UNIT
AIR FOR DIFFUSION
COOL & HOMOGENOUS
INFLUENT TO PH
CORRECTION TANK

56. PH
CORRECTION
 IN THIS TANK PH
OF THE INFLUENT IS
CORRECTED TO MEET THE STANDARD.
 ACID OR ALKALI IS ADDED TO THE
EFFLUENT BY DOZZING TO INCREASE OR
DECREASE THE PH
OF INFLUENT
RESPECTIVELY.
 MULTI-METER TYPE PH
METER IS USED.
PH
CORRECTION
ACID OR ALKALI
INFLUENT FROM
EQUALIZATION TANK
INFLUENT OF
DESIRED PH
TO
DISPERSE UNIT

57. DISPERSE UNIT
 FUNCTION OF DISPERSE
TANK IS TO MIX THE SLUDGE
COMING FROM RECYCLE
TANK WITH WASTE WATER.
 IT HELPS FOR PROPER
AERATION.
DISPERSE UNIT
( MIXING OF SLUDGE & WASTE)
SLUDGE FROM
RECYCLE TANK
INFLUENT FROM PH
CORRECTION
TANK
MIXED INFLUENT &
SLUDGE TO
AERATION

58. AERATION
 FUNCTION OF AERATION IS OXIDATION BY
BLOWING AIR.
 AEROBIC BACTERIA IS USED TO
STABILIZE AND REMOVE ORGANIC
MATERIAL PRESENTS IN WASTE.
 ABOUT 200 KG AEROBIC BACTERIA IS
GIVEN TO THE PLAN FOR 5 YEARS.
AERATION TANK
MIXTURE OF
WASTE
WATER &
SLUDGE
AEROBIC BACTERIA
AIR
DISCHARGE TO
SEDIMENTATION
TANK
O2
ORGANIC MATTER + O2
BACTERIA
NUTRIENT
CO2+ H2O + HEAT

59. Sedimentation pack
IN THIS TANK SLUDGE IS SETTLED DOWN
PARTIALLY
SEDIMENTATION PACK PROVIDES THE
ADVANTAGE OF FAST SLUDGE
SEPARATION
Sedimentation tank
 IN THIS TANK SLUDGE IS
SETTLED DOWN FINALLY.
 EFFLUENT IS DISCHARGED
FROM PLANT THROUGH A FISH
POND.
 SLUDGE IS PASSED TO THE
THICKENING UNIT.

60. SCHEMTIC DIAGRAM OF Sedimentation tank
SEDIMENTATION
TANK
WASTE WATER
FROM
SEDIMENTATION
PACK
SLUDGE TO
THICKENING UNIT
EFFLUENT
EFFLUENT
DISCHARGE
FISH POND
FISH POND INDICATES THE HIGHER DEGREE OF TREATMENT IN THIS ETP

61. SLUDGE THICKENING UNIT
IN THIS UNIT SLUDGE IS DRIED AND
DISCHARGED.
A PARTIAL AMOUNT OF SLUDGE IS
RETURNED BACK TO THE AERATION TANK
FROM THICKENING UNIT THROUGH
RECYCLE TANK CALLED RETURN SLUDGE
TANK AND DISPERSE TANK.
SLUDGFE
THICKENING UNIT
SLUDGE FROM
SEDIMENTATION UNIT
SLUDGE DISCHARGE
SLUDGE TO RECYCLE
TANK

62. RETURN SLUDGE TANK
FUNCTION OF RETURN TANK OR RECYCLE
TANK IS TO MIX WATER WITH SLUDGE
THIS MIXTURE IS THEN PASSED TO
AERATION TANK THROUGH DISPERSE TANK.
 SLUDGE AGAIN OXIDIZED TO MINIMIZE
THE POLLUTION FROM SLUDGE.
 ALIVE BACTERIA OF SLUDGE IS AGAIN
USED IN AERATION TO UTILIZE THIS
BACTERIA.
SLUDGE RECYCLE TANK
SLUDGE FROM
THICKENING UNIT
MIXING OF SLUDGE
& WATER
SLUDGE TO AERATION TANK
THROUGH DISPERSE UNIT

63. 800 KLD ELECTRO-CHEMICALS TREATMENT PLANT FOR TEXTILE
PROCESSING EFFLUENT
ENVIROS INDIA PRIVATE LIMITED
3.3.2