Effluent Treatment process

1. Wastewater Treatment in Knitwear Industry
Course Title : Industrial Water and Waste Treatment
Course Teacher:Professor Dr. Md. Habibur Rahman
Course No:6310
Prepared by
Md.Billal Hossain
Student ID# 1017042129
Department of Civil Engineering, BUET

2. Plummy Fashions Ltd: Profile
•Plummy Fashions is located in Narayanganj,
20 kilometers south from Dhaka city center.
The site is 5.5 acres.
•It is a LEED(Leadership in Energy &
Environmental Design) Platinum Certified
Apparel Manufacturing Factory.
•It is awarded by USGBC(U.S.Green Building
Council) for assuring a good contribution in
reduction in energy use, reduction in water
use, reduction in carbon footprint etc.

3. Industry Information
Industry Category: C (BKMEA)
Industry Category: RED Category(DoE)
Production Capacity : 8000 KG
Sustainable site: All the essential facilities
and amenities are located within 500 m,
including market, school, mosque, and bus
stops. The site also provides secure bicycle
parking facilities and encourages the use of
non-fossil fuel transport.
Rain Water Harvesting Rain water
is collected in a harvesting tank and
re-cycled for toilet flushing and
irrigation purposes.
Reduce Ozone Depletion-PFL has installed
CFC free refrigerants for chillers, air conditioning
and insulation.
CO2 Monitoring System- PFL has
installed carbon dioxide sensor to
monitor the level of CO2 in the
occupied areas.

4. Products and Raw Materials
Types of Raw Materials: Types of Products:
1.Yarn 1.T-Shirt
2.Fabric 2.Sweater
3.Dye Stuff 3.Woven
4.Chemicals
Process of Yarn to Fabric Finished Knit Products after dyeing

5. Dyeing & Washing
The following dyes are used:
• Reactive dye
•Disperse dye
•Acid dye
•Basic dye
•Direct dye
•Azoic dye
Dyeing Plant Washing Plant
Basic chemicals:
•Soda ash,
•Hydrochloric,
•Hydrogen peroxide,
•Sulphuric Acid,
•Acetic Acid,
•Formic acid,
•Caustic soda

6. Quality of discharge water
According to Environmental Conservation Rules 1997 textile industries are classified as Red
category industries and therefore an ETP must be designed and constructed to effectively treat
the waste water. The treated discharged water from the plant must meet the national effluent
discharge quality standard. Discharge quality standard for a composite textile industry are given
below:

7. Effluent Treatment Plant at Plummy
Fashion
Plant capacity =40m3/Hr
Treatment Mechanism : Physicochemical Treatment & Activated Sludge Process
Equalization Tank=400m3
Coagulation & Filtration Tank =2.7m3
Aeration Tank=814m3
Clarifier(Primary & Secondary)=220m3
Coagulant:FeSO4 /DCA(De-coloring Agent)
Flocculent used: PAC(Poly Aluminum Chloride)
Treatment Steps:
Preliminary Treatment
Primary Treatment
Secondary Treatment
Tertiary Treatment
Sludge Treatment

8. Waste
water
Grit
removal
tank
Equalizati
on tank
(400 m3)
Coagulation
Tank (2.7
m3)
Flocculation
Tank (2.7 m3)
FeSo4/DCA
Primary
Clarifier
PRIMARY
TREATM
ENT
Sludge
Holding-1
Sludge tank
-2 (RAS)-29
m3
Dry Sludge
Bed
Dry Sludge
Storage
SECONDARY
TREATMENT
Secondary Clarifier (220
m3)
PRELIMINARY
TREATMENT
Aeration
Tank (814
m3)
TERTIARY
TREATME
NT
Final
Treated
water
Reverse
Osmosis
RO
feed
Tank
Sand
Filter &
Activat
ed
Carbon
Filter
Treated
Water
Tank
Drain
Bar
Screen
SLUDGE
TREAT
MENT
DISPOS
AL
ETP Process Flow Chart

9. Screening
Bar Screen
The first unit operation encountered in wastewater-treatment plants is screening.
A screen is a device with openings, generally of uniform size that is used to retain the
coarse solids found in Waste water .
 Coarse screens remove large solids, rags, and debris from waste water, and typically
have openings of 6mm (0.25 in) or larger.

10. Objective of Using Equalization Basins
Equalization Tank
Reduction of temperature
Prevention of settle able solids from depositing
 Increase in DO
 Reduction of BOD5 of wastewater by 40%
Minimize or control fluctuations in wastewater characteristics and flow rate.
pH control :Minimize chemical requirements for neutralization
Minimize flow surges to physical – chemical treatment. Permit chemical feed rates
compatible with feeding equipment

11. Coagulation and Flocculation Unit
Coagulation Factors :Dose, Temperature, pH, mixing
time
Mechanical agitation in coagulation tank
Very slow wastewater motion in flocculation tank
Suspended particles do not settle
 Reduction of TSS of wastewater by 80%
Removal Of Organic Compounds and color from
synthetic effluents & polyester dyeing wastewater
 Reduction of COD up to 50%

12. Aeration with Activated Sludge
Process
In this industrial wastewater) treatment plant, the activated sludge
process ( biological process) is used for one or several of the following
purposes: oxidizing carbonaceous biological matter, oxidizing
nitrogenous matter: mainly ammonium and nitrogen in biological
matter, removing nutrients (nitrogen and phosphorus)
Aeration Tank

13. Clarifiers
Primary Clarifiers Secondary Clarifiers
The two main types of sludge are primary and secondary sludge.
Primary sludge is a result of the capture of suspended solids and organics in the
primary treatment process through gravitational sedimentation, typically by a
primary clarifier.
 The secondary treatment process uses microorganisms to consume the organic
matter in the wastewater. The microorganisms feed on the biodegradable material in
the wastewater in the aeration tank then flow into a secondary clarifier where the
biomass settles out and removed as secondary sludge.

14. RO(Reverse Osmosis) Plant Treatment
• The RO Treatment Plant is considered as the most Advanced solution for the
water treatment process in any commercial or industrial establishment.
Separating the contaminants and non essential and corrosive salts, metals,
chemicals etc from the water, the treatment plant is engineered using hi-tech
technology. The RO plant to give a high quality output of TDS in the water.
• Features
• Low water- rejection rate
• Most modern membrane technology
• Produce high quality de-mineralized water
• Less operational and maintenance cost
• Works on the cross filtration method
• Gives a unique high quality output of TDS range
• Output water have 99.9% of viruses and bacteria rejection
• Excellent system efficiency

15. Flow Chart of Reverse Osmosis(RO)
Raw Water Tank
Raw Water Pump
Sand Filter
Active Carbon Filter
Precise Filter
RO Membrane
Pure Water Tank
High Pressure pump

16. Treatment Operations and ProcessesTreatment Operations and Processes
Precise FilterSand & Activated Carbon Filter
Sand Bed Filter
• Overflow enters sand bed filter for clarification
• Filter comprises of layers of sand of various
particle sizes
Further reduction of residual
Reduction of BOD and COD
Activated Carbon Filter
• Advanced treatment; wastewater
polishing
• Mechanism of treatment: chemical
adsorption
Further reduction of TSS, TDS
 Removal of odor, color toxicity