Presented By: V. John Sundar CSIR Central Leather Research - - PowerPoint PPT Presentation

Presented By:

• V. John Sundar

CSIR – Central Leather Research Institute, India & Chennai Institute of Leather Technology Alumni Association, India

INTRODUCTION

Environmental Implications of Leather Processing

50 m3 liquid effluent containing COD 235 – 250 kg BOD5 100 - 120 kg Suspended solids 150 – 200 kg Chromium 5 – 6 kg Sulfide 10 – 12 kg Solid wastes / By-products Untanned Raw trimming 60 - 80 kg Fleshings 70 – 230 kg Tanned Tanned splits 110 - 120 kg Shavings + Trimming 100 -110 kg Dyed / finished 30 -- 35 kg Buffing dust 1 - 2 kg

Conventional Leather making implicates generation of substantial amount of liquid and solid wastes

Raw hide 1 ton 200 kg Leather

Resources - Present Status & Needed Initiatives

 Raw material

 Under Utilization

 Value Engineering

 Chemicals

 Excess usage leading to economic

loss and environmental concerns

 Substantive & eco-benign chemicals

 Water

 Copious use - Need to conserve

 Water free / Low-float

 Energy

 Intensive

 Shift to renewable resources

 Manpower

 Very low productivity

 Skilling and strengthening of

infrastructure

Preservation

 Less resource input  Better opening up of skin matrix  Fleshings converted into valuable

products

 Large quantities of salt used  Chlorides content in effluent exceeds

60000 ppm

 Chemical/Bio-additive assisted low salt

preservation developed

 Preservation with 20% salt + 2% soda

ash/MgO

 Successful commercial trials

 Substantial salinity reduction  Comparable leather quality

Low Salt Preservation Green Fleshing

Beam- house

 Replacement of lime with

enzymes

 Process duration less than 1 hr  Suitable for all substrates

Enzymatic Unhairing Fibre Opening Lime Splitting

 Flat & Firmer leathers  Less chromium consumption  Splits - Glue, gelatin, poultry feed

Lime and sulphide free Cleaner pelts Saving in water input (in drum) Substantial reduction in BOD, COD, Sulphides and TDS

Conventional Tanning : An Assessment

 Poses serious environmental constraint

 Technical challenges to treatment systems  Material and value loss  >85 % global leather production through chrome tanning

 8 – 10% salt employed in pickling  7 – 8% BCS employed in tanning  Exhaustion levels of 60% of Chromium is common  Discharge levels of 80000 – 100000 ppm of chlorides & TDS

and 5000 ppm of chromium not uncommon

Use of new auxiliaries Change in leather characteristics & restrictions Pickle recycle Quality consistency, Handling difficulties and carry over of >30% salt Direct chrome liquor recycling Handling and operational difficulties and carry over of salt Chromium recovery and reuse Pickling issues not addressed, Increase in neutral salts discharge, Greater process control need

Chrome Management

PROCESS FLOW DIAGRAM OF CHROME RECOVERY AND REUSE SYSTEM

CHROME TANNING DRUMS

Salt free Tanning Technology

Process TDS (ppm) Chromium (g/lit ) Chlorides (ppm) Salt free 6000 0.09±0.01 Nil Conventional 98800 0.62±0.01 84400±10

Spent pickle tan liquor analysis

Successful commercial trials Saudi Arabia Srilanka Indian Tanneries > 100

Salt free Zero emission Tanning Technology - An overview

 Total elimination of common salt and mineral acid for pickling & tanning  The technology uses only conventional tanning chemicals and does not call for

use of any new chemical

 Affords reduction in tanning material input  Significant reduction in process duration  The technology is suitable for all substrates and product-mix  Minimizes total dissolved solids in effluent

 Technology does not call for any change in infrastructure  Leads to chromium exhaustion exceeding 90% in tanning  The process ensures minimization of chromium discharges in post tanning

• perations

ECO - BENIGN SIMPLE ECONOMICAL VERSATILE SZCT Technology

Chrome Free Tannages

 Safe & Durable  Eco – benign  Versatile  Full Vegetable tanning / full organic tanning

systems

 Tara, Oxazolidine, Organic phosphonium salts  Combination of Vegetable – Acrylic / aldehyde  Combination of Vegetable – Plant oils  Suitable for diabetic footwear

Post Tanning

Avoiding REACH restricted chemicals Use of benign & safe chemicals Minimizing water usage Ensuring near zero chemical discharge by employing substantive chemicals

Water Management

 Use of optimized / rationalized volume of

water

 Use of water meters / aqua mix system  Recycling of spent liquors without treatment /

recovery wherever possible (eg: liming)

 Segregation and management of sectional

waste streams (eg: soaking)

 Modification of process to maximize

absorption to make spent liquor suitable for recycling (eg: Better exhaustion of chromium)

Resource Management through Process Control

Benefits

 Product consistency

 Minimum rejections  Better manpower utilization  Reduction in wastages

 Hide float ratio  pH  Chemical preparation and mode

• f addition

 Duration  Temperature

Parameters controlled

Keratinous Wastes - Hair

 Home furnishings - Rugs and carpets  Hair protein as animal feed  Keratin hydrolysate through alkali or enzymatic hydrolysis

 As exhaust aid in chrome tanning and rechroming  During post tanning – for filling and retanning

Bio-Fertilizer

 Conversion of proteinous trimmings & fleshings  Excellent nitrogen source

 Enriched with mineral P and K  Biometric observations encouraging

 Employed as plant growth promoters

Syntan Poultry feed

 Enzymatic digestion of fleshings  Used as exhaustion aid in chrome tanning  Used as Protein syntan  Limed fleshings rich in protein  Hide fleshings mixed with carbohydrate

residues

 As an animal feed additive - Provides

food supplement amino acid

CHARACTERISTICS VALUE Dry matter 38-40% Ash 8-9% Protein 36-40% Yield 80-85% pH range of application 2.5-8 Molecular weight 5000 – 30000 kD CHARACTERISTICS VALUE Moisture 6-7% Total Ash 10-12% Crude Protein 22-30% Fibre 13-15% Ether extract 8-9% Insoluble Ash 5-6%

Protein Syntan

 Chrome shavings constitute 40-50% of the

solid wastes

 Hydrolysis under alkaline condition  Chromium and collagen protein is separated  Can be coupled with acrylics  Leather filling and retanning agent

Leather Board – Tanned Wastes

Chrome/ Vegetable tanned shavings Pulp Rubber latex Coagulated mass Filter Sheet & Pressed Dried Leather board

Used in leather goods as supplementary; as insole in shoes; chappal uppers and as sound proofing material

THANK YOU