FUNDED BY THE EUROPEAN COMMISSION S ustainable and C leaner Production in the Manufacturing I ndustries of Pak istan SCI-Pak Mar Feb 2012

 Chemicals intensive industry. About 400 different types of chemicals are used  No chemical monitoring and record keeping  Hazardous chemicals. Unsafe chemical handling and storage practices  Mostly chemicals feeding is not properly controlled. Excessive amounts are used.  Hard and high TDS water is used which consumes more chemicals

 No recovery or reuse of chemicals  No softening and RO treatment of boiler feed water rather chemical treatment is carried out.  Chemicals leakage and spillage

 Chemical consumption monitoring and record keeping  Benchmarking for optimum chemical consumption

 Controlled chemical feeding (Measured quantities are added in the process vessels)  Use of soft water in the process  Reuse of steam condensate as boiler feed water (Chemical treatment can be reduced)  Use of soft and RO treated water as boiler feed water (Chemical treatment can be reduced)  Control of leakage and spillage of chemicals

Caustic Recovery Plant Reduction in 45-75% of fresh caustic soda purchase Payback ◦ Within One year

 Ultra filtration technology  Water soluble sizes (PVA, poly acrylates, carboxy methyl cellulose)  80-85% recovery  COD load reduction 40-70%

 Mercerization wash water in scouring process  Mercerization wash water as dilution water in mercerization process

 High float (More water, more chemicals are consumed)  No monitoring of chrome contents in the wastewater (No process laboratory)  No recovery and recycling of the chrome  No recycling of lime and sodium sulfide in the liming process  Use of salted hides (10-12% more soaking chemicals are consumed)

 Chemicals are not measured properly (scales are not calibrated)  Spillage and leakage of chemicals in chemical store and during chemical handling

 Float control (low float)  On the basis of chrome contents in wastewater, process parameters are controlled i.e. pH, float control (5-10% reduction in chrome consumption)  Chrome recovery and recycling  Lime recycling (20-25% reduction in lime and sodium sulfide)  Use of desalted hides (10-12% reduction in soaking chemicals)

 De-liming with CO 2 gas from boiler flue gas (30-50% reduction in ammonium sulfate )  Measured quantities of chemicals feeding (Calibration of scales)  Leakage and spillage control

Chrome Recycling Controlling Factors pH of tanning liquor required (2.4) Chrome concentration pH of tanning liquor discharged (basification) (3.9) Maintaining Float Tanning Drum Tanning Discharge Chrome Liquor Storage Tank

Chrome tanning liquor is collected into the trolley

Chrome tanning waste liquor from trolley to the chrome drain- It will be transferred to the chrome collection pit

Chrome Recycling Reactor

Basis: Production = 10,000 Kg/d of Raw Hides Chrome 5% = 500 Kg Chrome wasted per day (25%) = 125 Kg/d Capital Cost of the Plant = Rs. 650,000 Operational cost (Chemical, electricity)= Rs. 300,000/yr Maintenance cost = Rs. 32,500/year Total Operational Cost = Rs. 332,500

Saving due to Rs. 100/Kg = Rs. 3,500,000 /yr Net Profit/yr = 3,500,000 – 332,500 = Rs. 3,167,500 Pay back = 3 months Benefit

Chrome Recovery MgO slurry tank sulphuric acid tank tanning drum precipitation tank treatment tank storage tank sieve liquor holding tank or sump sludge supernatant to effluent plant

Chrome Recovery Plant

The gear box and motor for stirrer on the Reactor

Caustic tank for maintaining the pH of the liquor to 8.5

Filter Press for filtering chrome liquor to remove precipitations

Scrapper fitted below the filter press to carry the chrome sludge to the sludge dissolving tank

Chrome Regeneration Tank

Recovered chrome on left side with dark colour and decanted water on right side Recovered chrome in the Chrome regeneration tank

Daily Production = 10,000 Kg of Hides Amount of chromium sulfate used (5%) = 500 Kg/d Chromium wastage (25%) = 125 Kg/d Chromium recovered (99.9%) = Kg Cost of chromium sulfate = Rs. 100/Kg Capital Cost of the Plant = Rs. 1,200,000 Operational and Maintenance cost = Rs. 1,450,000 Saving of chrome/yr = 35,000 Kg/yr Saving in Rs. = Rs. 3,500,000 Net Saving = Rs. 2,050,000/yr Pay back = 7 months

BOILER COOLING TOWER SCRUBBER COOLING WATER PUMP STACK GASES TO ATMOSPHERE STACK GASES TO DE-LIMING SYSTEM HEAT EXCHANGER TO BLOWERS CO 2 DELIVERY BLOWERS DE-LIMING DRUMS TANYARD CO 2 De-liming System

CO 2 Requirement Chemical reaction with lime is as illustrated below: Ca (OH) 2 + (NH4) 2 SO 4 = Ca SO NH 4 OH Where as the reaction of CO2 with the lime is as given below: Ca (OH) 2 + CO 2 = Ca CO 3 + H 2 O Kg of (NH 4 ) 2 SO 4 will be replaced by 0.33 Kg of CO 2 CH 4 + 2O 2 + N 2 = N 2 + CO 2 + 2H 2 O (16) (64) (28) (28) (44) (36) CH 4 Requirement One Kg of CH 4 produces 2.75 Kg of CO 2

Hot flue gas extraction duct from boiler

Hot flue gas duct coming out of boiler room and entering into the heat exchanger Hot flue gas duct from heat exchanger to CO 2 scrubber

CO 2 scrubber with cooling tower & water circulation pipes Cool CO 2 gas duct from blowers

Cool gas duct through dry finishing section Cool CO 2 gas injection into the de-liming drum

Basis: Hide Delimed annually = 20,000 Kg/d Capital cost = Rs. 1,625,000 Annual O& M cost = Rs. 216,000 Benefits due to reduction in Ammonium sulfate = Rs. 1,400,000 Net benefits = Rs. 1,184,000/yr Pay back = 1.37 yr

De-salting before wet processing; by Manually Desalting or by Machines

Cage type drum

Butter fly machine Brush type machine De-salting drum

Operation : Raw to Wet blue Total Weight of Hides = 10,000 kg Weight after De-dusting = 8,750 kg Salt produced after De-Dusting = 1,250 kg /day Conc. of salt in pickle solution = 8-9 Be Working days = 280

Capital Cost of Salt De-dusting Machine = Rs. 400,000 Electricity cost = Rs. 20,000 Maintenance cost = Rs. 10,000 Depreciation cost = Rs. 20,000 Rs Total Operation & Maintenance Cost = Rs. 50,000

Chemicals saving (12.5% reduction in lime, sodium sulfide, anti bacteria, detergent = Rs. 600,000 Net Annual Saving = 600,000 – 50,000 = Rs. 550,000 Pay Back = 9 Months

Lime Recycling Chemical Saving Sodium sulfide reduction 25-30% Lime reduction 25-30% Environmental Benefits BOD reduction Suspended Solids reduction Mixing Tank Filtered Liming Liquor Recycled Liming Liquor Liming Drum

Basis Weight/lot Processed = 10,000kg/day Lime Ca(OH) % = 300 kg/day Sodium sulfide (Na 2 S)1.0 % = 100 kg/day Lime in spent liquor (30%) = 90 kg/day Sodium sulfide in spent liquor (35%) = 35 kg/day

Capital Cost = Rs. 700,000 Electricity cost = Rs. 30,000 Maintenance cost = Rs. 17,500 Depreciation cost = Rs. 35,000 Annual Operational & Maintenance Cost = Rs. 82,500 Total Chemical Savings = Rs. 500,000 Net Annual Profit =500,000-82,500 Net Annual Profit = Rs. 417,500 Pay Back = 20 months