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Waste min

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  • 1. WASTE MINIMISATION - FEW CASE STUDIES Dr. R.B. CHAVAN PROFESSOR, DEPARTMENT OF TEXTILE TECHNOLOGY, INDIAN INSTITUTE OF TECHNOLOGY, HAUZ KHAS, NEW DELHI - 110016 INDIA
  • 2. WASTE MINIMISATION TECHNIQUES
    • WATER CONSERVATION
    • OPTIMISATION OF CHEMICAL USAGE
    • PROCESS INNOVATIONS
    • SUBSTITUTION OF NON-ECOFRIENDLY CHEMICALS
  • 3. AVERAGE WATER CONSUMPTION IN TEXTILE CHEMICAL PROCESSING
    • FIBRE WATER CONSUMPTION
    • (l/kg)
    • COTTON 50 - 200
    • WOOL 75 - 300
    • SYNTHETIC FIBRES 10 - 100
  • 4. WATER CONSUMPTION
    • POSSIBILITIES TO ACHIEVE 25% CONSERVATION IN SOME CASES
    • REDUCE TOTAL EFFLUENT VOLUME
    • TOTAL POLLUTION LOAD
  • 5.
    • WASTE MINIMISATION THROUGH PROCESS OPTIMISATION
    • SIZING AGENT
    • STARCH MOST COMMON SIZING AGENT
    • HIGH BOD
    • CONTRIBUTE ~ 50% BOD LOAD
    • DEGRADATION DURING DESIZING
    • RECOVERY NOT POSSIBLE
    • MEASURE
    • REPLACE STARCH BY PVA
    • RECOVER PVA
    • LESS EFFLUENT LOADING
    • COST SAVING
    • APPLICATION NOT SUITABLE FOR SMALL AND MEDIUM MILLS
    • PVA COST IS HIGH
    • EXPENSIVE PVA RECOVERY SYSTEM (ULTRA FILTRATION )
  • 6.
    • MODIFICATION OF DESIZING PROCESS
    • HYDROLYTIC DESIZING
    • ENZYME OR ACID DESIZING
    • DEGRADATION PRODUCTS CONTRIBUTE TO BOD
    • OXIDATIVE DESIZING
    • HYDROGEN PEROXIDE
    • PERSULPHATE
    • DEGRADATION PRODUCTS
    • CARBON DIOXIDE
    • WATER
    • FREE FROM EFFLUENT LOAD
    • PROBLEMS
    • FORMATION OF OXY-CELLULOSE
    • PRECAUTION
    • CONTROL OVER CHEMICAL CONCENTRAION, TIME AND TEMPERATURE
  • 7.
    • USE OF NEW ENZYMES
    • NEW ENZYMES DEVELOPED FOR HOME LAUNDRING MARKET DEGRADE STARCH TO ETHANOL
  • 8.
    • TRANSFER PRINTING
    • CONVENTIONAL PRINTING (SEQUENCE)
    • PREPARATION OF COLOUR PASTE
    • PRINTING
    • DRYING
    • FIXATION
    • WASHING
    • EFFLUENT LOAD
    • DISCHARGE OF UNUSED PRINT PASTE
    • WASHING OF DESIGN SCREENS AND PRINT BLANKET
    • WASHING OF PRINTED FABRIC
  • 9.
    • TRNSFER PRINTING
    • SEQUENCE
    • PRINT PAPER
    • DRY
    • TRANSFER OF DESIGN ON FABRIC
    • NO WASHING OPERATION AT TEXTILE MILL
    • DRY PROCESS
    • SUITABLE FOR POLYESTER ONLY
  • 10.
    • WASTE MINIMISATION THROUGH ADVANCED DYEING
    • TWO WAYS TO SOLVE POLLUTION PROBLEM
    • EFFLUENT TREATMENT
    • REDUCING WASTE GENERATION AT SOURCE
    • WAYS TO MINIMISE DYE WASTE
    • LOWER LIQUOR RATIO
    • PROCESS OPTIMISATION AND INNOVATIONS
    • SUBSTITUTION OF OFFENDING DYES AND CHEMICALS
  • 11.
    • LOWER LIQUOR RATIOS
    • THIS APPROACH HELPS IN
    • REDUCTION IN TOTAL EFFLUENT VOLUME
    • REDUCTION IN THE QUANTITY OF CHEMICALS USED WHERE CHEMICAL CONCENTRATION EXPRESSED IN g/l
    • REDUCTION IN POLLUTION LOAD
    • EXAMPLE
    • DYEING OF COTTON WITH VAT OR REACTIVE DYE
    • CHANGE OF LIQUOR RATIO FROM 10 : 1 TO 5 : 1
    • DECREASE IN POLLUTION LOAD ~ 40%
  • 12.
    • PROCESS INNOVATION
    • VERY IMPORTANT STEP TOWARDS WASTE MINIMISATION
    • CLOSE INTERACTION BETWEEN PROCESSORS, DYESTUFF MANUFACTURERS AND MACHINERY MANUFACTURERS IS ESSENTIAL
  • 13.
    • CASE STUDY
    • DYEING OF COTTON WITH LOW SALT REACTIVE DYES
    • SALT REQUIRMENT
    • CONVENTIONAL REACTIVE DYES 30 - 80 g/l
    • LOW SALT REACTIVE DYES 20 g/l
  • 14.
    • EFFECT OF HIGH SALT CONCENTRATION ON ENVIRONMENT
    • REMOVAL OF ONLY SMALL QUANTITY OF SALT DURING EFFLUENT TREATMENT
    • MAJOR QUANTITY OF SALT REMAINS IN EFFLUENT WATER
    • RIVERS AND LAKES POLLUTED BY HIGH INFLUX OF DYE EFFLUENTS CONTAINING HIGH SALT CONCENTRATION
    • FRESH WATER ORGANISMS CAN SUFFER TOXIC EFFECT
    • IN REGIONS WITH SCARCE FRESH WATER RESOURSES, SUCH WASTE WATER HAS TO BE USED FOR IRRIGATION
    • HOWEVER, IF THE SALT
    • CONCENTRATION IS TOO HIGH SOIL MAY BECOME OVER LOADED WITH SALT AND THE LAND MAY BECOME INFERTILE AND ULTIMATELY HAVE TO BE ABONDONED
  • 15.
    • APPROACHES TO SOLVE PROBLEM OF SALT LOAD
    • DYEING AT LOWEST POSSIBLE LIQUOR RATIO
    • USING DYE CLASSES OTHER THAN REACTIVE e.g. VAT REQUIRING LOW SALT CONCENTRATION FOR DYEING
    • USING REACTIVE DYES GIVING HIGH EXHAUSTION AND FIXATION AT LOW SALT CONCENTRATION
  • 16.
    • LOW SALT REACTIVE DYES
    • BI-REACTIVES
    • MEDIUM REACTIVITY
    • STABLE DYE FIBRE BOND
    • TWO CHROMOPHORES CONTRIBUTE TO HIGH AFFINITY AND HIGH COLOUR STRENGTH
    • HIGH EXHAUSTION AND FIXATION AT LOW SALT CONCENTRATION
  • 17.
    • THE SALT REQUIREMENT IS REDUCED TO 1/4th COMPARED TO CONVENTIONAL REACTIVE DYES
    • RINSING STEP AFTER DYE FIXATION IS MUCH FASTER AND LESS WATER IS NEEDED
    • LOW SALT DYES GIVE HIGHER FIXATION THAN CONVENTIONAL DYES
    • THIS LEADS TO LOWER DYE CONCENTRATION IN THE EFFLUENT
  • 18.
    • LOW SALT DYES ARE AN EXAMPLE OF ECOLOGICAL PRODUCT DESIGN THAT CONTRIBUTES TO A SAFER AND HEALTHIER ENVIRONMENT
    • THEY ADDRESS SOME URGENT ENVIRONMENTAL PROBLEMS SIMPLY BY NOT CREATING THEM IN THE FIRST PLACE
  • 19. SUBSTITUTION OF OFFENDING DYES AND CHEMICALS
    • SUBSTITUTION OF DYES
    • AVOID USING DYES WHICH FALL UNDER THE PREVIEW OF GERMAN REGULATIONS
    • SUBSTITUTES ARE AVAILABLE FOR MOST SUCH PRODUCTS
    • LEADING DYESTUFF MANUFACTURERS CERTIFY FOR THE ECO-FRIENDLINESS OF THEIR PRODUCTS
  • 20. SUBSTITUTION OF CHEMICALS IN DYEING
    • ACETIC ACID IS USED IN LARGE QUANTITIES FOR DYEING OF POLYESTER, WOOL, SILK, NYLON AND ACRYLIC
    • IT CONTRIBUTES MORE THAN 15% OF COD, BOD LOAD IN EFFLUENT
    • REPLACEMENT BY FORMIC ACID SIGNIFICANTLY LOWERS COD AND BOD LOAD
    • BOMBAY TEXTILE RESEARCH ASSOCIATION HAS DEVELOPED A BUFFER SYSTEM WHICH IS FREE FROM DRAW BACKS OF ACETIC ACID AND EFFECTIVELY MAINTAINS THE DYEBATH pH
  • 21. SUBSTITUTION OF SODIUM HYDROSULPHITE IN VAT DYEING
    • UNIVERSELY USED REDUCING AGENT FOR REDUCTION OF VAT DYES
    • DECOMPOSITION OF SODIUM HYDROSULPHITE IN EFFLUENT LEADS TO FORMATION OF SEVERAL BY PRODUCTS SUCH AS SODIUM SULPHATE, SODIUM BISULPHITE, SODIUM THIOSULPHATE, SODIUM SULPHIDE etc. THESE CONTRIBUTE TO POLLUTION LOAD
    • AN ECO-FRIENDLY PRODUCT BASED ON Fe (II) COMPLEX HAS BEEN DEVELOPED AT IIT DELHI
  • 22.
    • SUBSTITUTION OF SODIUM SULPHIDE BY GLUCOSE IN SULPHUR DYEING
    • SULPHUR DYES ARE INSOLUBLE IN WATER
    • FOR SOLUBILISATION USE OF SODIUM SULPHIDE AND SODA ASH ARE NECESSARY
    • SULPHUR BLACK MOST WIDELY USED
    • AFTER DYEING TOXIC SODIUM SULPHIDE GOES IN TO EFFLUENT UNDER ACIDIC CONDITIONS SODIUM SULPHIDE DECOMPOSES LIBERATING HYDROGEN SULPHIDE WHICH HAS SMELL OF ROTTEN EGGS
    • SULPHUR COMPOUNDS ARE TOXIC TO FISH
    • IT IS THEREFORE NECESSARY TO REPLACE SODIUM SULPHIDE IN SULPHUR DYEING
  • 23.
    • CASE STUDY
    • CENTURY TEXTILE MILL MUMBAI HAS IDENTIFIED AN ECO - FRIENDLY REDUCING AGENT “HYDROL” AS A SUBSTITUTE OF SODIUM SULPHIDE IN SULPHURE DYEING
    • HYDROL IS A BY-PRODUCT IN (IN LIQUID FORM) OF MAIZE STARCH INDUSTRY
    • HYDROL CONTAINS REDUCING SUGAR WHICH UNDER ALKALINE CONDITIONS (NaOH) ACT AS REDUCING AGENT AT DYEING TEMPERATURS ( 80 - 85 O C )
    • HYDROL IS COST EFFECTIVE ENVIRONMENT FRIENDLY SUBSTITUTE OF SODIUM SULPHIDE
    • THE RESULTS OF THIS SUBSTITUTION ON EFFLUENT PLANT WERE ENCOURAGING
  • 24.
    • NOT ONLY SULPHIDE IN THE EFFLUENT WAS REDUCED BUT IHE AERATION SYSTEM WORKED BETTER IMPROVING SETTLING CHARACTERISTICS OF THE EFFLUENT
    • THE FOUL SMELL ASSOCIATED WITH SODIUM SULPHIDE IS ELIMINATED
    • AT PRESENT 3500 kg OF COTTON IS BEING DYED EVERY DAY IN THIS WAY
    • NO CAPITAL EXPENDITURE IS INVOLVED IN THIS SUBSTITUTION
  • 25.
    • STUDY AT IIT DELHI
    • A PROJECT IS IN PROGRESS AT DEPT. OF TEXTILE TECHNOLOGY, IIT , DELHI , FOR THE IN HOUSE PREPARATION OF REDUCING SUGAR BY THE HYDROLYSIS OF CARBOHYDRATE BASED PRODUCTS AND ITS USE FOR DYEING OF COTTON WITH SULPHUR DYES
  • 26.
    • CASE STUDY
    • POLLUTION CONTROL IN WET PROCESSING (RADHA KANHAIYA PROCESSORS, ICHALKARANJI)
    • ICHALKARANJI- INDUSTRIAL TOWN IN MAHARASHTRA STATE
    • POWER LOOMS 65000
    • SMALL PROCESSING UNITS 25
    • HAND PROCESSING UNITS 15
    • SPINNING MILLS 20
    • DYE HOUSE EFFLUENT DISPOSAL WITHOUT TREATMENT INTO PUBLIC SEWER OR INTO RIVER CAUSING SERIOUS PROBLEM FOR IRRIGATION AND THREAT TO ENVIRONMENT
    • SOME PROCESSORS TRIED TO TREAT EFFLUENT HOWEVER THE TREATMENT WAS INADEQUATE AND EFFLUENT NOT CONFIRMING TO THE NORMS OF POLLUTION CONTROL BOARD
  • 27.
    • A STUDY WAS CONDUCTED AT TEXTILE ENGINEERING INSTITUTE, ICHALKARANJI AND EFFLUENT PLANT WAS SET UP AT A PROCESS HOUSE TO DEAL WITH THE EFFLUENT WATER DISPOSAL
    • TOTAL PRODUCTION 40,000 m / day
    • FABRICS PROCESSED
    • POLYESTER, POLYESTER / COTTON AND POLYESTER / VISCOSE BLENDS
    • PROCESSES CARRIED OUT
    • DESIZING
    • SCOURING
    • MERCERISATION
    • BLEACHING
    • DYEING
    • FINISHING
    • EFFLUENT GENERATED 2,25,000 lit / day
  • 28.
    • CHARACTERISTICS OF COMBINED EFFLUENT
    • BEFORE AFTER
    • mg/l mg/l
    • 1. pH 10 - 11 9 - 10
    • 2. T.D.S. 3200 - 3700 2000 - 2050
    • 3. S.S. 650 - 900 350 - 575
    • 4. B.O.D. 270 - 325 150 - 190
    • 5. C.O.D. 1200 - 1700 700 - 915
    • 6. CHLORIDES 750 - 950 300 - 450
    • 7. SULPHATE 500 - 950 500 - 650
    • 8. OILS & GREASES 15 - 17 9 - 11
  • 29.
    • EFFLUENTS GENERATED IN VARIOUS DEPARTMENTS PER DAY
    • BLEACHING AND FINISHING 1,10,000 lit
    • DYEING 95,000 lit
    • DOMESTIC AND SANITORY 20,000 lit
    • TOTAL EFFLUENT 2,25,000 lit
  • 30.
    • MEASURES TAKEN
    • REDUCTION IN WASTE VOLUME
    • REDUCTION IN CONCENTRATION OF DYES, CHEMICALS USED
    • REDUCTION IN WASTE CONCENTRATION THROUGH RECOVERY AND REUSE
    • REDUCTION IN WASTE CONCENTRATION BY CHEMICAL SUBSTITUTION
    • REDUCTION IN WASTE CONCENTRATION BY PROCESS MODIFICATION
    • DESIGNING OF SUITABLE EFFLUENT TREATMENT PLANT
  • 31.
    • REDUCTION IN WASTE VOLUME
    • MEASURES
    • LEAKAGE OF WATER THROUGH PIPES, TAPS AND VALVES WAS STOPED BY REPLACING CORRODED PIPES AND TAPS
    • NUMBER OF WASHING DURING BLEACHING OF POLYESTER / COTTON ON JUMBO JIGGER WERE REDUCED FROM 3 TO 2
    • THE FINAL WASH WATER AFTER BLEACHING WAS UTILISED FOR GIVING FIRST WASH TO THE NEXT FABRIC LOT
    • COUNTER CURRENT SYSTEM OF WASHING WAS EMPLOYED ON MERCERISATION RANGE FOR EFFICIENT REMOVAL OF CAUSTIC SODA FROM FABRIC
    • M:L IN JET DYEING WAS BROUGHT DOWN FROM 1:10 TO 1:8
    • IN THIS WAY A REDUCTION OF 20 - 30% IN VOLUME OF WASTE WATER
  • 32.
    • REDUCTION IN CONCENTRATION OF DYES, CHEMICALS AND AUXILIARIES
    • MEASURES
    • INTRODUCTION OF COMPUTRE COLOUR MATCHING SYSTEM HELPED TO USE OPTIMUM DYEING RECEIPS
    • REDUCTION IN SALT CONCENTRATION BY 5 - 10 %
    • NEW FINISH FORMULATIONS WHERE IN OPTIMUM FINISHING CHEMICALS, AUXILIARIES WERE USED
  • 33.
    • REDUCTION IN WASTE CONCENTRATION
    • MEASURES
    • CAUSTIC RECOVERY FROM MERCERISING MACHINE ENHANCED FROM 60 % TO 80 % BY EFFICIENT WASHING OPERATION
    • LEFT OVER FINISHING FORMULATIONS WERE REUSED INSTEAD OF DISCHARGING INTO THE DRAIN
    • IN THE CARBONISING PROCESS FOR THE DISSOLUTION OF CELLULOSIC COMPONENT IN POLYESTRE BLEND, SULPHURIC ACID WAS REUSED AFTER REMOVING THE SOLID IMPURITIES BY FILTRATION
    • SOME PART OF THIS ACID WAS USED FOR LOWERING THE pH OF COMBINED EFFLUENT
  • 34.
    • REDUCTION IN
    • WASTE CONCENTRATION
    • BY CHEMICAL SUBSTITUTION
    • MEASURES
    • USE OF MINERAL ACID (0 BOD) IN PLACE OF ACETIC ACID (60 %)
    • USE OF DETERGENT HAVING LOW BOD IN PLACE OF SOAP (HIGH BOD)
  • 35.
    • EFFECT OF THE MEASURES TAKEN
    • REDUCTION IN TOTAL EFFLUENT VOLUME FROM 2,25,000 lit /day TO 2,00,000 lit / day
    • REDUCTION IN POLLUTION LOAD BY 40 - 45 %
  • 36.
    • EFFLUENT TREATMENT
    • SINCE THE DISPOSAL WAS NOT IN TO THE MUNICIPAL SEWERAGE BUT DIRECTLY IN TO STREAM, PRIMARY TREATMENT FOLLOWED BY SECONDARY TREATMRNTS BECAME ESSENTIAL
    • FOLLOWING OPERATIONS WERE ADOPTED
    • SCREENING
    • EQUALISATION
    • ACID DOSING
    • COAGUALATION
    • SEDIMENTATION
    • ACTIVATED SLUDGE PROCESS
    • SECONDARY SETTLING
    • FILTRATION
    • ACTIVATED CARBON TREATMENT
  • 37.
    • SCREENING
    • REMOVAL OF
    • COARSE FLOATING MATTER LIKE FIBRES AND LINTERS
    • HEAVY AND READILY SETTELABLE GRIT AND DIRT
    • EQUALISATION
    • MIXING OF EFFLUENT FROM VARIOUS DRAINS AND ITS EQUALISATION FOR ~8 HOURS
    • TAKE CARE OF WIDE VARIATIONS AND PREVENTION OF SHOCK LOADS
    • HELP IN SELF NEUTRALISATION OF ACIDIC AND ALKALINE STREAMS
  • 38.
    • ACID DOSING
    • pH CORRECTION FOR IMPROVING THE EFFICIENCY OF SUBSEQUENT TREATMENT
    • EFFLUENT pH BROUGHT DOWN FROM 9 - 10 TO 8 BY ADDING SULPHURIC ACID FROM THE CARBONISATION PROCESS
    • CONTROL OF SULPHURIC ACID ADDITION BY pH MEASURMENT
    • CHEMICAL COAGULATION
    • CARRIED OUT IN FLASH MIXER
    • ADDITION OF REQUIRED QUANTITIES OF ALUM AND POLYELECTROLITE
    • EFFECTIVELY REMOVED COLOUR AND SUSPENDED MATTER LIKE STARCH etc.
    • REDUCTION IN BOD TO AN EXTENT OF 70 - 75 %
  • 39.
    • SEDIMENTATION
    • CARRIED OUT IN SUITABLY DESIGNED PLATE SAPERATOR
    • THE FLOCULATED SOLID GOT SETTLED AT THE BOTTOM FORMING A SLUDGE
    • REMOVAL OF THE CLEAR SUPERNATENT LIQUID FROM THE TOP
    • REMOVAL OF SEDIMENTED SOLIDS AFTER 4 - 6 HOURS WITH THE HELP OF MUD PUMP AND TRANSFERING THE SLUDGE TO THE DRYING BEDS
    • ACTIVATED SLUDGE PROCESS / AERATION
    • THE MIXING OF SUPERNATENT LIQUOR WITH ACTIVATED SLUDGE IN A BIG TANK
    • AERATION FOR 8 HOURS
  • 40.
    • SECONDARY SETTLING
    • FLOW OF LIQUOR CONTAINING ACTIVATED SLUDGE INTO SETTLING TANK
    • SLUDGE SEPERATION AND ITS RECYCLING TO AERATION TANK
    • CLEAR SUPERNATENT LIQUOR
    • FILTRATION
    • REMOVAL OF SUSPENDED AND PRECIPITETED PARTICALS WITH THE HELP OF FILTER BED COMPRISING OF GRAVEL AND SAND OF VARIOUS SIZES
    • ACTIVATED CARBON TREATMENT
    • REMOVAL OF COLOUR, ODOUR AND CHLORINE
    • CLEAR WATER SUITABLE FOR DISCHARGE IN TO RIVER
  • 41.
    • CHARACTERISTICS OF EFFLUENT AFTER ACTIVATED CARBON TREATMENT
    • A B
    • 1. pH 6 - 9 7 - 7.5
    • 2. Temperature 40 O C 30 - 35 O C
    • 3. T.D.S.(mg/l) 2100 1950 - 2100
    • 4. S.S. (mg/l) 100 20 - 25
    • 5. BOD (mg/l) 30 25 - 35
    • 6. COD (mg/l) 250 175 - 200
    • 7. Chloride (as Cl mg/l) 600 250 - 425
    • 8. Sulphate(as SO4 mg/l) 1000 300 - 500
    • 9. Oils and Greases (mg/l) 10 6 - 8
    • 10. Total resudial Chlorine 1 0.3 - 0.5
    • Bio assay test 90 % survival in 96 hours
    • A: TOLERANCE LIMITS FOR DISCHARGE IN TO
    • INLAND SURFACE WATER
    • B: TREATED EFFLUENT
  • 42.
    • THE TREATED EFFLUENT WAS FOUND TO BE SUITABLE FOR DIRECT DISCHARGE IN TO RIVER
    • COST
    • TREATMENT PLANT
    • FOR 2,00,000 lit /day Rs. 3,00,000
    • RUNNING EXPENSES Rs. 18,000/month

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