Effluent treatment plantDOC

7/30/2019 Effluent treatment plantDOC

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Effluent Treatment Plant

National Institute Of Fashion Technology -Jodhpur Page 1

SUSTAINABLE PRODUCTION

Topic


(Performance Evaluation of Effluent Treatment Plant for Textile Industry)

Submitted by:

Kush Sharma

DFT

NIFT-Jodhpur


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CONTENTS

Topics Page No.

Abstract 03 Introduction 04

o Pollution Control Boardo Water treatmento Textile waste principleo Evaporation process

Separation process 08 Result and Discussion 10 References 12


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ABSTRACT:

Textile dyeing industries need huge quantity of water for textile dyeing, which they normally pump out

repeatedly from the ground or natural water sources resulting in depletion of ground water level.

In the dyeing process textile industries generate huge quantity of toxic effluent containing colours,

sodium sulphate, sodium chloride, sodium hydroxide and traces of other salts. These are generated after

dyeing and after washing of garments / fabrics. After dyeing the waste water produced is called Dye Bath

water and after washing the waste water generated is called wash water. Dye Bath contains higher solids

in the range 4-5% whereas wash water contains only 0.5-1% solids.

An effluent treatmentplant is operating on biological treatment method (Fluidized Aerobic Bio-Reactor)

with an average wastewaterinflow of 2MLD has been considered for case study. The wastewater is

analyzed for the major water qualityparameters, such as pH, Biological Oxygen Demand (BOD),

Chemical Oxygen Demand (COD) and Total DissolvedSolids (TDS). The effluent samples were

collected on a daily basis for a period of one month. The rawwastewater pH was highly alkaline it was

then bringing down to neutral which was helpful for biologicaltreatment. The BOD, COD of the treated

effluent reduced significantly, whereas very small reduction wasobserved in dissolved solids.


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INTRODUCTION

The textile industry is one of the leading sectors inthe Indian economy as it contributes nearly 14percent

to the total industrial production(business.mapsofindia.com). The untreated textilewastewater can causerapid depletion of dissolvedoxygen if it is directly discharged into the surfacewater sources due to its high

BOD value. Theeffluents with high levels of BOD and COD values arehighly toxic to biological life. The

high alkalinity andtraces of chromium which is employed in dyesadversely affect the aquatic life and also

interferewith the biological treatment processes.The quality of such effluent can beanalyzed by their

physico-chemical and biologicalanalysis. Monitoring of the environmentalparameters of the effluent

would allow having, atany time, a precise idea on performance evaluationof ETP and if necessary,

appropriate measures maybe undertaken to prevent adverse impact onenvironment. The obtained results

were very muchuseful in identification and rectification ofoperational and maintenance problems and it

can bealso utilized to establish methods for improvedtextile industry and plant waste minimization

strategies. The present textile industry is having weavingcapacity of 10 million meter per annum. During

theproduction process, effluent generated in the plantis drain to ETP. The samples collected daily

andanalyzed for Physico-chemical and biologicalparameter except BOD as it takes three days foranalysis

for the period of one month during thetraining period. On average, approximately 200 litersof water are

required to produce l kg of textiles. Therisk factors are primarily associated with the wetprocesses-

scouring, desizing, mercerizing, bleaching,dyeing and finishing. Desizing, scouring andbleaching

processes produce large quantities ofwastewater. The large volumesof wastewater generated also contain

a wide varietyof chemicals used throughout processing. These cancause damage if not properly treated

before being discharged into the environment.

Table 1: Effluent Characteristics from Textile Industry

Process Effluent composition Nature

Sizing Starch, waxes, carboxymethyl cellulose (CMC),

polyvinyl alcohol (PVA), wetting agents.

High in BOD, COD

Desizing Starch, CMC, PVA, fats, waxes, pectins. High in BOD, COD, SS, dissolved solids

(DS)Bleaching Sodium hypochlorite, Cl2, NaOH, H2O2, acids,

surfactants, NaSiO3, sodium phosphate, short cottonfibre

High alkalinity, high SS

Mercerizing Sodium hydroxide, cotton wax High pH, low BOD, high DS

Dyeing Dyestuffs urea, reducing agents, oxidizing agents,

acetic acid, detergents, wetting agents.

Strongly colored, high BOD, DS, low

SS,heavy metals

Printing Pastes, urea, starches, gums, oils, binders, acids, Highly colored, high BOD,


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Thickeners, cross-linkers, reducing agents, alkali oilyappearance, SS slightly alkaline, low

BOD

Source: Yusuff and Sonibare

Pollution Control Board comprises of the following units:

1] Screen Chamber

2] Equalization tank

3] Flash mixer

4]Flocculation Tank

5] Tube Settler-I

6] Fluidized Aerobic Bio-Reactor (FAB-I)

7] FAB-II

8] Tube Settler-II

9] Chlorine Contact Tank

10] Sludge Thickener

11] Centrifuge.

The wastewater generated from the plant iscollectively passed through the screen chamber toremove the

floating matter present in thewastewater. The quality and quantity of thewastewater is maintained in the

equalization tankwhere air blower is provided for the supply ofoxygen. The wastewater then comes to the

flashmixer in which lime and ferrous sulphate are thecoagulants added to the wastewater with

detentiontime of 30 seconds. The floc gets formed due to theslow mixing and resultant settling of floc in

the firsttube settler reduces total suspended solids and BODload on the secondary treatment. The water is

the allowed in the FAB-I where micro-organisms areattached to the media while media is suspended Ithe

wastewater. The growth occurred on the media.The oxidation of organic matter is done with the

help of micro-organisms. The sludge formed due tobiological process gets settled in the tube settler II.

The wastewater treated by secondary treatment isthen allowed in chlorine contact tank to killpathogens

using the hypochlorite as a disinfectant.The treated wastewater is then sending to thecommon effluent

treatment plant for furthertreatment. The sludge settled in the tube settlers isthen sending to the sludge

thickener then it isconcentrated in centrifuge using poly electrolytedosing. The concentrated sludge is


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send to thehazardous waste disposal site. The samples collected on daily basis and brought tothe

laboratory for analysis of various environmentalparameters. The BOD and COD were analyzed

usingStandard Methods for The Examination of Water andWastewater (APHA, 1998). COD was

determined bythe dichromate digestion method while BOD wasdetermined by the dilution method. TDS

is analyzedby portable digital TDS meter manufactured by EIElectronics. TDS meter was checked and

calibratedaccording to the manufacturers specifications. TDS was calibrated using the potassium chloride

solutionprovided by the manufacturer.


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The technology offered by SSP can overcome all problems pertaining to environmental pollution in

respect to textile dying industries.The basic thrust of the technology is to convert entire quantity of

effluent to zero level by separating water and salt using evaporation and separation technology.

The concept and the treatment is based on the removal of the entire COD/BOD and the condensate

coming out to meet the fresh water quality requirement in the process.

Textile Waste Water Handling By Evaporation And Solid Separation Basic Principle:

The technology is based on basic principle of reduction of quantity by concentrating the effluent and

subsequently separation of salt and water.

The Evaporation Process:

Textile Effluent is fed to the vacuum evaporator to concentrate up to 40% solids concentration. The total

process is under vacuum and the vapors generated in the system are re-used to economize steam

consumption in multiple effect evaporation system with thermal vapour recompression system. The

thermal vapour recompression system use Vapours generated in the evaporator and compress it by steam

and the compressed vapours are used as heating medium in the evaporator, in this way steam

consumption is reduced. Water recovered from the evaporator has low COD/BOD value and can be

recycled in the plant.


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Separation Process

(zero liquid discharge section):

DYE BATH / WASH WATER EFFLUENT

The resultant slurry (concentrate) is fed to the thickener and centrifuging section for converting the liquid

concentrate to solid waste. The mother liquor from thickener and centrifuge is recycled back to

evaporator.

The water separated out from evaporator is good enough in quality to recycle in the plant for Dyeing.

Key features:

Zero Liquid Discharge Fully Customized Designed System Highest Steam Economy Low Operating Cost Less Downtime for Maintenance Generation of Reusable Condensate Water Operator Friendly


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RESULTS AND DISCUSSION

For evaluating the performance of ETP,the accurate idea of the composition of effluents isvery important.

This is so because industrialeffluents contain various pollutants that may alterthe quality of the receiving

water and the environment at large. Theresults of daily analysis of pH, COD, BOD and TDS etc are

represented in Table 2.

The color of the effluent was brownish black. Incompleteuse and the washing operations give thetextile

wastewater a considerable amount of dyes. It has been documentedthat residual color is usually due to

insoluble dyeswhich have low biodegradability as reactive blue 21,direct blue 80 and vat violet with


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COD/BOD ratio of59.0, 17.7 and 10.8 respectively.The coagulation and flocculation helps toremove

color of the effluent. The pHof the raw effluent is very high as the incomingwastewater is highly alkaline

in nature. Thebleaching agents used in the process are reasons forhigh alkaline wastewater. The pH

correction is donewith the help of HCL and brings down to neutralwhich is favorable pH for biological

treatment. TDSare composed mainly of carbonates, bicarbonates,chlorides, phosphates and nitrates,

calcium,

magnesium, potassium and manganese, organicmatter salts and other particles. No appreciablechange was

observed in values of dissolved solids intreated effluent. TDS detected could bethe high color from the

various dyestuffs being used in the textile mills.

The COD and BOD of raw effluent varied from 1104to 1475 mg/l and 242 to 358 mg/l respectively.

Higher values of COD and BODin raw effluentattributed to the presence of chemical substancesand

breakdown of raw material used for preparationof fiber respectively. The COD and BOD of

treatedeffluents were reduced significantly to a greaterextent due to the biological treatment process

forwhich the effluent is passed throughFAB I and II.

Most of the studied parameters are well within thepermissible limit prescribed by MPCB because

theindustry has installed adequate treatment system totreat the raw effluent. The treated effluent

isapplicable for land application so it is used for greenbelt development in the industrial premises and

30%of the total effluent treated is reused for thispurpose. The disposal of excess of treated effluentto

common effluent treatment plant is best andeffective and environmentally acceptable option forbetter

downstream conditions.

FAB consists of a tank filled with specially developedmedia. These media are made of special material

ofsuitable density that can be fluidized using anaeration device through diffusers. A biodevelops on the

media, which move along the

effluent in the reactor. The movement within thereactor is generated by providing aeration with helpof

diffusers placed at the bottom of the reactor. Thisthin film on the media enables the bacteria to actupon

the bio-degradable matter in the effluent andreduce BOD/COD content in presence of oxygenfrom the air

used for fluidization.


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REFERENCES

C Parvathi, T Maruthavanan and C Prakash(2009): Environmental impacts of textileindustries.The Indian Textile Journal

PalamthodiShanooba, DhirajPatil and YatinPatil,(2011): Microbial degradation of textileindustrialeffluents. AfricanJournal of Biotechnology10(59).

APHA, AWWA, WPCF,for the Examination of Water and Wastewater.20th edition, AmericanPublic Health AssociationWashington, DC, New York, USA.

Deepti Mishra, Mohdakram khan, Manishmudgal, prabhapadmakaran and B Chakradhar,(2009):performance evaluation of an effluenttreatment plant for a pulp & paper mill. IndianJournal of

Chemical Technology. Vol 16.

K. Sundara Kumar, P. Sundara Kumar, Dr. M. J.RatnakanthBabu, (2010): PerformanceEvaluationof Wastewater Treatment Plant.International Journal of Engineering Science andTechnology,

Vol. 2(12).

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