Sustainable
Development of China
Leather Industry
By: Prof. Gao Zhongbai
Tel:86-10-6433 7975
E-mail:g_zhongbai@163.com
Contents
1
• Brief introduction of China Leather &
Footwear Industry Research Institute
(CLFI)
2
• Situation of China Leat...
China Leather & Footwear Industry Research
Institute (CLFI), founded in Beijing in 1959, is
the top national, professional...
China Leather & Footwear
Industry Research Institute
Professional
Departments
Dept. of Science & Tech.
Dept. of Leather
St...
 National Research Center of Leather and Leather
Products Engineering Technology
 China Leather & Footwear Productivity ...
 Twinning Secretariat of ISO/TC 137
 National Center for Fur & Leather Standardization
 National Center for Footwear St...
 more than 160 employees, including 11 Professors,
35 Senior Engineers, 5 Ph.D., 1 Doctoral Supervisor
and 5 advisor of m...
 Leather Technologies
 Footwear Technologies
 Chemicals
 Footwear Materials
 Synthetic Leather
 Environmental Protec...
 National fur and leather standards center, National
footwear standards center, and also responsible to
ISO/ TC120、TC137、...
 China Leather Industry Information Center and
National Footwear Industry Information Center edit
and publishe China Leat...
 The China Leather and Footwear Website
(www.leather365.com) and China Leather and
Footwear International Industrial Subc...
 The training course of The Ecological Tanning Technology (Eco-
Leather) for Developing Countries commissioned by Ministr...
1
• Brief introduction of China Leather &
Footwear Industry Research Institute
(CLFI)
2
• Situation of China Leather Indus...
Leather
Industry
Main
Industry
Leather Industry
Footwear Industry
Fur Industry
Leather Goods
Assist
Industry
Chemicals
Mac...
2. Situation of China Leather Industry
Development
 China leather industry covers the main industry of
leather making, fo...
Animals
Hides &
Skins Goods
Meat
Leather
& Fur
Human
(2) The Leather Industry = The permanency Industry
(3) The pollution can be treated and controlled
Wastes and wastewater from tannery can be treat by
environmental technolog...
 There are more than 5 million employees in the
large-scale leather enterprises
 In the whole leather industry with the ...
2. Situation of China Leather Industry
Development
Leading economic figures of China leather, fur
and the goods industries...
2. Situation of China Leather Industry
Development
Leading economic figures of China leather, fur
and the goods industries...
2. Situation of China Leather Industry
Development
Leading economic figures of China leather, fur
and the goods industries...
2. Situation of China Leather Industry
Development
Review:
From above related data, we can see all
performance of China le...
2.4 Main Problems Existing in China Leather
industry Development
2.4.1 Pressure by Environment Protection
 Not only to co...
2.4 Main Problems Existing in China Leather
industry Development
2.4.2 The Price of Raw Materials
(1) Raw hides
 From Jan...
2.4 Main Problems Existing in China Leather
industry Development
2.4.3 Labor Cost
 Labor cost of tannery increased;
 The...
1
• Brief introduction of China Leather &
Footwear Industry Research Institute
(CLFI)
2
• Situation of China Leather Indus...
3. Clean Production
3.1 Issues must be cautioned by tannery
3.1.1 Ammonia can not be easy to meet the discharge standard
i...
3.1 Issue must be cautioned by tannery
3.1.3 Sludge disposal
 Land-filling being the environmental hidden trouble
 Chrom...
3. Clean Production
Problem must be in caution — Chrome will be released during
Retanning and Dyeing Process
Process for c...
3. Clean Production
1230
800
550
1080
750
490
0
200
400
600
800
1000
1200
1400
Tanning Washing Washing Retanning Washing N...
3. Clean Production
0
10
20
30
40
50
60
0
20
40
60
80
100
120
140
160
5% 10% 15% 5% 10% 15% 5% 10% 15%
Cr2O3inLeather(mg/g...
3. Clean Production
0
5
10
15
20
25
30
35
40
45
50
0
50
100
150
200
250
300
350
400
5% 10% 15% 5% 10% 15% 5% 10% 15%
Cr2O3...
3. Clean Production
Problem must be in caution — Chrome will be released during
Retanning and Dyeing Process
 Retanning b...
3. Clean Production
Problem must be in caution — Chrome will be released during
Retanning and Dyeing Process
 In fating a...
 After chrome tannage, Cr3+ could also appear during follow-up
process (like: washing, retanning, neutralizing, dyeing, s...
3.2 Sustainable Technologies for Chrome Control
Method 1 — extend chrome recovery chain
3. Clean Production
Exhaust Chrome...
3. Clean Production
Gathering Clearing
Reacting Pressing
3. Clean Production
3.2 Sustainable Technologies for Chrome Control
Method 2 — Wet White Technology
Advantage :
 No-salt ...
3. Clean Production
3.2 Sustainable Technologies for Chrome Control
Method 2 — Wet White Technology
 Tanning with 3~5% TW...
3. Clean Production
3.2 Sustainable Technologies for Chrome Control
Method 2 — Wet White Technology
Process for wet white ...
3. Clean Production
3.2 Sustainable Technologies for Chrome Control
Method 2 — Wet White Technology
Results of Ts and chro...
3. Clean Production
3.2 Sustainable Technologies for Chrome Control
Method 2 — Wet White Technology
3. Clean Production
Promoting dyeing and
f...
3. Clean Production
3.2 Sustainable Technologies for Chrome Control
Method 2 — Wet White Technology
Without heavy metal, e...
3. Clean Production
3.3 Waste and Pollution-loading Control during Process
Clean Technology (reduce the waste and pollutio...
3. Clean Production
3.3 Waste and Pollution-loading Control during Process
Hairing-saving system
 Combination function be...
3. Clean Production
0.1% enzyme, 2h 0.3% enzyme, 2h 1.0% enzyme, 2h
0
15
30
45
60
75
HypconcentrationinWW
(mg/L)
Doage of ...
3. Clean Production
3.3 Waste and Pollution-loading Control during Process
Enzyme-unhairing agent (no collagen proteolytic...
3. Clean Production
3.3 Waste and Pollution-loading Control during Process
Enzyme-unhairing agent —— Hairing-saving System...
3. Clean Production
3.3 Waste and Pollution-loading Control during Process
Enzyme-unhairing agent —— Hairing-saving System...
3. Clean Production
3.3 Waste and Pollution-loading Control during Process
Enzyme-unhairing agent —— Hairing-saving System...
3. Clean Production
3.3 Waste and Pollution-loading Control during Process
Enzyme-unhairing agent —— Hairing-saving System...
3. Clean Production
3.3 Waste and Pollution-loading Control during Process
Hairing-saving System Optimization Process with...
1
• Brief introduction of China Leather &
Footwear Industry Research Institute
(CLFI)
2
• Situation of China Leather Indus...
4. Pollution Control in Tannery
+
Water
consumption
30~60 m3
Chemicals
500~550kg
1 Tonne
Raw Hides
320~350 kg
Finished
Lea...
Quality of influent unit: mg/L
4. Pollution Control in Tannery
pH CODCr SS CrTotal S2- N-NH3
8~9 4000~5000 2000~3000 10~15...
4. Pollution Control in Tannery
Equalization
Reaction
Settling
DAF
A/O
Treatment
Influent Effluent
Sludge
Activated
Sludge...
Note: * indirectly discharge standard (industry area)
4. Pollution Control in Tannery
Quality of effluent unit: mg/L
pH CO...
4.4 Individual treatment technology
 Unhairing wastewater treatment
4. Pollution Control in Tannery
Acidification
Reactor...
4. Pollution Control in Tannery
4.4 Individual treatment technology
 Chrome-bearing wastewater treatment
Reaction
Reactor...
4. Pollution Control in Tannery
4.5 Tertiary Treatment Technology
 RO (Ultrafiltration and Reverse Osmosis) treatment
—— ...
4. Pollution Control in Tannery
4.5 Tertiary Treatment Technology
 Land application (reed, vetiver grass, sedge, water
sh...
4. Pollution Control in Tannery
4.5 Tertiary Treatment Technology
 Fixed film treatment —— for ammonia and nitrogen remov...
4. Pollution Control in Tannery
Dewatering Drying
Dryed Sludge
4.6 Sludge Treatment
 After sludge thickening, sludge is d...
4. Pollution Control in Tannery
The author thanks China Leather Industry Association
and ASSOMAC of Italy.
Acknowledgements
Tel: +86-10-6433 7975
Fax: +86-10-6435 1739
E-mail: g_zhongbai@163.com
www.clf.cn
www.leather365.com
Sustainable Development of China Leather Industry
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Sustainable Development of China Leather Industry

  1. 1. Sustainable Development of China Leather Industry By: Prof. Gao Zhongbai Tel:86-10-6433 7975 E-mail:g_zhongbai@163.com
  2. 2. Contents 1 • Brief introduction of China Leather & Footwear Industry Research Institute (CLFI) 2 • Situation of China Leather Industry Development 3 • Pollution Control in Tannery 4 • Clean Production
  3. 3. China Leather & Footwear Industry Research Institute (CLFI), founded in Beijing in 1959, is the top national, professional and comprehensive research organization in China leather and footwear industry. 1.1 Brief Introduction of CLFI
  4. 4. China Leather & Footwear Industry Research Institute Professional Departments Dept. of Science & Tech. Dept. of Leather Standardization and Test Dept. of Footwear Standardization and Test Dept. of Information Zhongpi Tianyuan Corporation Management Departments Administration Dept. Finance Dept. Property Management Dept. 1.2 Structure of CLFI
  5. 5.  National Research Center of Leather and Leather Products Engineering Technology  China Leather & Footwear Productivity Promotion Center  Technological Service Center for Import & Export Commodity of Ministry of Commerce (Leather &Leather Products)  National Center for Leather Products Quality Supervision and Inspection  National Center for Footwear Quality Supervision and Inspection 1.3 Organizations in CLFI
  6. 6.  Twinning Secretariat of ISO/TC 137  National Center for Fur & Leather Standardization  National Center for Footwear Standardization  National Committee of Standardization for Leather Industry  National Committee of Standardization for Footwear  China Leather Industry Information Center  National Footwear Industry Information Center  Training Centre on the UNIDO Project of Tanning Pollution Control 19 National and International Centres set up in CLFI 1.3 Organizations in CLFI
  7. 7.  more than 160 employees, including 11 Professors, 35 Senior Engineers, 5 Ph.D., 1 Doctoral Supervisor and 5 advisor of master 1.4 Staffs
  8. 8.  Leather Technologies  Footwear Technologies  Chemicals  Footwear Materials  Synthetic Leather  Environmental Protection  Leather Wastes Recovering and Reusing 1.5 Main Fields of R & D
  9. 9.  National fur and leather standards center, National footwear standards center, and also responsible to ISO/ TC120、TC137、TC216.  National footwear Inspection and Testing Center, National leather products Inspection and Testing Center and National leather and footwear equipment Inspection and Testing Center are also set up in CLFI. 1.6 Testing and Standardization
  10. 10.  China Leather Industry Information Center and National Footwear Industry Information Center edit and publishe China Leather, Moda Shoes, and China Leather Review, and also offer information service. 1.7 Information and Media
  11. 11.  The China Leather and Footwear Website (www.leather365.com) and China Leather and Footwear International Industrial Subcontracting and Exchange Network (www.clfspx.com) are built by the Centre. 1.7 Information and Media
  12. 12.  The training course of The Ecological Tanning Technology (Eco- Leather) for Developing Countries commissioned by Ministry of Commerce, P. R. C  Training course of Tannery Pollution Control entrusted by UNIDO Project  Technical training for leather and footwear production  Training for footwear stylists  Training for leather and footwear testing technology 1.8 Training
  13. 13. 1 • Brief introduction of China Leather & Footwear Industry Research Institute (CLFI) 2 • Situation of China Leather Industry Development 3 • Pollution Control in Tannery 4 • Clean Production
  14. 14. Leather Industry Main Industry Leather Industry Footwear Industry Fur Industry Leather Goods Assist Industry Chemicals Machine Shoes materials Hardwares 2.1 Background of Leather Industry (1) The Industry 2. Situation of China Leather Industry Development
  15. 15. 2. Situation of China Leather Industry Development  China leather industry covers the main industry of leather making, footwear, leather garment, leather goods, fur and related products, as well as complete set assistant industries  It characterizes of complete industry chain, upstream and downstream products in high relation
  16. 16. Animals Hides & Skins Goods Meat Leather & Fur Human (2) The Leather Industry = The permanency Industry
  17. 17. (3) The pollution can be treated and controlled Wastes and wastewater from tannery can be treat by environmental technologies.
  18. 18.  There are more than 5 million employees in the large-scale leather enterprises  In the whole leather industry with the assistant industry, the number of employees reached 11 million 2.2 Situation of China Leather Industry Development 2. Situation of China Leather Industry Development
  19. 19. 2. Situation of China Leather Industry Development Leading economic figures of China leather, fur and the goods industries of 2010. ① Gross Industrial Output 2.3 Production, Imports & Exports Situation Date Gross Industrial Output Growth Rate 2010 115.14 billion U.S. dollars +26.9 % Source: National Bureau of Statistics
  20. 20. 2. Situation of China Leather Industry Development Leading economic figures of China leather, fur and the goods industries of 2010. ② Exports 2.3 Production, Imports & Exports Situation Source: National Bureau of Statistics Date Export Value Growth Rate 2010 53.83 billion U.S. dollars +33.8%
  21. 21. 2. Situation of China Leather Industry Development Leading economic figures of China leather, fur and the goods industries of 2010. ③ Imports 2.3 Production, Imports & Exports Situation Source: National Bureau of Statistics Date Imports Value Growth Rate 2010 6.11 billion U.S. dollars +34.0%
  22. 22. 2. Situation of China Leather Industry Development Review: From above related data, we can see all performance of China leather industry kept increasing the production benefit, although affected by the financial crisis worldwide. The growth of export & import in 2010 also kept increasing speedly as a whole. 2.3 Production, Imports & Exports Situation
  23. 23. 2.4 Main Problems Existing in China Leather industry Development 2.4.1 Pressure by Environment Protection  Not only to control COD and SO2, but also ammonia, TN (total nitrogen) and chloride;  Problem for total chrome control;  Clean technologies employing: including water-saving, cleaning unhairing, short chrome discharge, etc. 2. Situation of China Leather Industry Development
  24. 24. 2.4 Main Problems Existing in China Leather industry Development 2.4.2 The Price of Raw Materials (1) Raw hides  From Jan. to Dec. of 2010 Imported raw hide : 1.23 million ton (-3.8%), 2.03 billion USD (+41.1%);  From Jan. to Jul. of 2011 Imported raw hide: 0.623 million ton (-2.8%), 1.28 billion USD (32%); (2) Chemicals cost increased 5~15%. 2. Situation of China Leather Industry Development
  25. 25. 2.4 Main Problems Existing in China Leather industry Development 2.4.3 Labor Cost  Labor cost of tannery increased;  The downstream products industry is labor-intensive industry, great labor cost increasing impact s the leather industry. 2. Situation of China Leather Industry Development
  26. 26. 1 • Brief introduction of China Leather & Footwear Industry Research Institute (CLFI) 2 • Situation of China Leather Industry Development 3 • Pollution Control in Tannery 4 • Clean Production
  27. 27. 3. Clean Production 3.1 Issues must be cautioned by tannery 3.1.1 Ammonia can not be easy to meet the discharge standard in WW  Ammonia concentration from tannery: 60~300 mg/L in general  Ammonia discharge standard in China: 15mg/L for first grade and 25 mg/L for second grade 3.1.2 Total Chrome can not be easy to meet the discharge standard in WW  Total chrome from tannery normal is about 3mg/L in general  The discharge standard is lower than 1.5 mg/L (outlet of workshop)
  28. 28. 3.1 Issue must be cautioned by tannery 3.1.3 Sludge disposal  Land-filling being the environmental hidden trouble  Chrome content in sludge: Cr2O3 0.8-20 g/Kg (dry basis), more difficult to disposal 3.1.4 Chloride control  Chloride concentration from tannery: around 4500~5500 mg/L  New standard: 3000mg/L (in coming) 3. Clean Production
  29. 29. 3. Clean Production Problem must be in caution — Chrome will be released during Retanning and Dyeing Process Process for conventional chrome tannage and retannage Process Operation Chrome tannage Float 50%, Chrome powder 7~8%, running 2h, overnight, basifying pH=3.9, horsing-up Samming and shaving Washing – 1 Float 400% Bleaching Float 200%, formic acid 0.2%, degreasing agent 0.3%, running 40 min Chrome ratannage Float 150%, 38℃, chrome powder 4%, running 60 min, basifying pH=4.0~4.2, overnight Washing – 2 Float 200% Neutralizing Float 200%, neutralizing agent 2% Filling Float 100%, tannin or synthetic tannin 3~5%, 2h Dyeing Dyeing agent 1~5% Stuffing Stuffing agent 6~16% Dye fixed Formic acid 0.5%, pH=3.8~4.0
  30. 30. 3. Clean Production 1230 800 550 1080 750 490 0 200 400 600 800 1000 1200 1400 Tanning Washing Washing Retanning Washing Neutralization Cr2O3ConcentrationinWW(mg/L)  After Cr tanning, more Cr will be appeared during washing, retanning and neutralizing.  Cr content only improved 7.8% after retanning and 3.6% after neutralizing. Problem must be in caution— Chrome will be released during Retanning and Dyeing Process
  31. 31. 3. Clean Production 0 10 20 30 40 50 60 0 20 40 60 80 100 120 140 160 5% 10% 15% 5% 10% 15% 5% 10% 15% Cr2O3inLeather(mg/g) Acrylic Retanning Agent Cr2O3inWW(mg/L) Cr2O3 in WW Cr2O3 in Leather RD ART-1 ART-2  Retanning by Acrylic Agent, Cr2O3 in WW from 40 ~ 110 mg/L (float ratio: 1:1) Problem must be in caution— Chrome will be released during Retanning and Dyeing Process
  32. 32. 3. Clean Production 0 5 10 15 20 25 30 35 40 45 50 0 50 100 150 200 250 300 350 400 5% 10% 15% 5% 10% 15% 5% 10% 15% Cr2O3inLeather(mg/g) Cr2O3inWW(mg/L) Vegetable Tannin Extract Cr2O3 in WW Cr2O3 in Leather Wattle Tara BA Problem must be in caution — Chrome will be released during Retanning and Dyeing Process  Retanning and filling by Vegetable agent, Cr2O3 in WW from 150 ~ 350 mg/L (float ratio: 1:1)  More Cr2O3 appeared in WW by Mimosa tannin extract.
  33. 33. 3. Clean Production Problem must be in caution — Chrome will be released during Retanning and Dyeing Process  Retanning by Syntans, Cr2O3 in WW from 150 ~ 250 mg/L (float ratio: 1:1) 0 10 20 30 40 50 60 0 50 100 150 200 250 300 350 5% 10% 15% 5% 10% 15% Cr2O3inLeather(mg/g) Cr2O3inWW(mg/L) Synthetic Tanning Agent Cr2O3 in WW Cr2O3 in Leather OS STF
  34. 34. 3. Clean Production Problem must be in caution — Chrome will be released during Retanning and Dyeing Process  In fating and dyeing WW, Cr2O3 concentration from 160 ~ 300 mg/L (float ratio: 1:1)  After fixed dye, Cr2O3 concentration from 80 ~ 170 mg/L (float ratio: 1:1). 0 50 100 150 200 250 300 6% 12% 16% 6% 12% 16% 6% 12% 16% 6% 12% 16% Cr2O3inWW(mg/L) Fating, Dyeing and fixed Before fixed After fixed DDF NFS Sulfating Compounded Fating
  35. 35.  After chrome tannage, Cr3+ could also appear during follow-up process (like: washing, retanning, neutralizing, dyeing, stuffing……). Chrome content in integrated WW could not meet the discharge standard easily and stably (CrTotal ≤ 1.5mg/L), and chrome concentration of sludge could be over the standard (CrTotal ≤ 300 mg/kg dry sludge).  Chrome tanning and chrome retanning, around 20 ~ 40% Cr2O3 will appear in WW. The effective method to reduce the chrome discharge is to improve chrome utilization ratio. 3. Clean Production Problem must be in caution— Chrome will be released during Retanning and Dyeing Process
  36. 36. 3.2 Sustainable Technologies for Chrome Control Method 1 — extend chrome recovery chain 3. Clean Production Exhaust Chrome Tannage Fixative agent Sammying Retanning Washing ………. Chrome WW Collection Tank Reaction Tank Alkali Flocculate Treatment Chrome Sludge Reuse Technical measure:  Chrome-bearing individual collection area;  Chrome recovery and reuse technology;  Water-saving and recycle technology.
  37. 37. 3. Clean Production Gathering Clearing Reacting Pressing
  38. 38. 3. Clean Production 3.2 Sustainable Technologies for Chrome Control Method 2 — Wet White Technology Advantage :  No-salt pickling; no chloride discharge; chrome dosage reduced about 50%; chrome discharge lower .  Ts 80~86℃, easy splitting and shaving;  promoting retanning agent, fatliquoring agent and dyeing materials absorbing;  no affect to waste reusing.
  39. 39. 3. Clean Production 3.2 Sustainable Technologies for Chrome Control Method 2 — Wet White Technology  Tanning with 3~5% TWT (wet white tanning agent), Ts > 80℃. 74 76 78 80 82 84 86 88 2% 3% 4% 5% 6% 7% Ts℃ Offer %
  40. 40. 3. Clean Production 3.2 Sustainable Technologies for Chrome Control Method 2 — Wet White Technology Process for wet white making: Process Chemicals Quantity added (%) Temperature (℃) Action/Run time (min) pH Tanning Water/fatliquoring agent 50.0.5 TWT 4 120 6.8~7.0 Water 150 40 180 7.0~7.2 Overnight, running 30 min, shaving Washing Water/degreasing agent 300/0.3 30 Chrome tanning Water/syntans 100/1.5 30 Formic acid 1.2 15×3 3.6 Chrome powder 4~6 90 3.6 Sodium formic 1.0 30 Sodium bicarbonate 1.0 15×3+30 3.9~4.0 Water 100 40 60
  41. 41. 3. Clean Production 3.2 Sustainable Technologies for Chrome Control Method 2 — Wet White Technology Results of Ts and chrome content in WW with different chrome dosage (TWT 4%) Chrome dosage/% 4 5 6 8 Ts/℃ 98 105 108 112 Chrome content in WW/(g/L) 0.20 0.24 0.30 0.41
  42. 42. 3. Clean Production
  43. 43. 3.2 Sustainable Technologies for Chrome Control Method 2 — Wet White Technology 3. Clean Production Promoting dyeing and fatliquoring absorption Increasing chrome absorption  With wet white, absorptivity of dye and fatliquor > 97%;  Colour leather is colormetric purity.
  44. 44. 3. Clean Production 3.2 Sustainable Technologies for Chrome Control Method 2 — Wet White Technology Without heavy metal, easy reuse Waste Hydrolysis by alkaline Hydrolytic liquor Industrial protein Gelatin
  45. 45. 3. Clean Production 3.3 Waste and Pollution-loading Control during Process Clean Technology (reduce the waste and pollution-loading)  Hairing-saving technology —— sludge could be reduced more than 80%, pollution-loading could be reduced more than 70%;  Splitting limed hide. Hairing-saving Process Splitting limed hide
  46. 46. 3. Clean Production 3.3 Waste and Pollution-loading Control during Process Hairing-saving system  Combination function between chemical and enzyme reaction, either reducing the chemicals quantity added, or making the enzyme usage in the safe;  Na2S usage < 1%, and lime usage < 3%. Pollution-loading was reduced by a wide margin. Hair remove (Filter) The technology trend for future —— enzyme-unhairing agent, without collagen proteolytic enzyme
  47. 47. 3. Clean Production 0.1% enzyme, 2h 0.3% enzyme, 2h 1.0% enzyme, 2h 0 15 30 45 60 75 HypconcentrationinWW (mg/L) Doage of enzyme / % 2 h 6 h 0.1% 0.2% 0.3% 0.5% 1% 3.3 Waste and Pollution-loading Control during Process Normal Enzyme agent (containing proteolytic enzyme agent) T=25 ℃, Float=0.5, Enzyme=0.1%~1%  no-completely unhairing;  more quantity added, more grain damage;  longer running-time, more collagen protein loss.
  48. 48. 3. Clean Production 3.3 Waste and Pollution-loading Control during Process Enzyme-unhairing agent (no collagen proteolytic enzyme)  Optimum pH = 7~8;  Comparing normal enzyme agent, the activity of collagen proteolytic enzyme of Enzyme-unhairing agent is inhibited, unhairing process become more safely. Effect of pH on enzyme unhairing activity Under 1g/L enzyme at 25 ℃, hydroxyproline concentration in unhairingliquor
  49. 49. 3. Clean Production 3.3 Waste and Pollution-loading Control during Process Enzyme-unhairing agent —— Hairing-saving System  Optimum usage of enzyme-unhairing agent 0.2 ~0.3%  No any damage for the grain. No enzyme 0.05% 0.1% 0.2% 0.3% F=0.5, normal T℃, X% enzyme- unhairing agent, 30 min. F=1, lime 1%, 60 min; drain F=0.5, Na2S 1.2%, 10 min; salt 1.5%, 60 min.
  50. 50. 3. Clean Production 3.3 Waste and Pollution-loading Control during Process Enzyme-unhairing agent —— Hairing-saving System Optimization  Even Na2S usage is 0.6%, the clean grain of pelt, without guard hair and short hair. Enzyme+0.6%Na2S Enzyme+0.4%Na2S 0.6%Na2S F=0.5, normal T℃, 0.2% enzyme-unhairing agent, 30 min. F=1, lime 1%, 60 min; drain F=0.5, Na2S X%, 10 min; salt 1.5%, 60 min.
  51. 51. 3. Clean Production 3.3 Waste and Pollution-loading Control during Process Enzyme-unhairing agent —— Hairing-saving System Optimization Hair Separator
  52. 52. 3. Clean Production 3.3 Waste and Pollution-loading Control during Process Enzyme-unhairing agent —— Hairing-saving System Optimization  Even lime usage is increased to 2%, hair could also be removed.  More lime usage, removed hair longer. F=0.5, normal T℃, 0.3% enzyme-unhairing agent, 30 min; F=1, Lime X%, 60 min; drain F=0.5, Na2S 0.8%, 10 min; salt 1.5%, 60 min.
  53. 53. 3. Clean Production 3.3 Waste and Pollution-loading Control during Process Hairing-saving System Optimization Process with Enzyme-unhairing agent Soaked Hide F=0.5, normal T ℃, enzyme-unhairing agent 0.3%, 30 min F=1, lime 1%, 60 min; drain F=0.5, Na2S 0.8%, 10 min; salt 1.5%, 45 min Lime 2%, 60 min; 5’/30’ ×4; Swelling agent 0.5%, 20 min; added water to F=3, 10 min; overnight 5’/30’ Advantage:  no any damage for grain;  beneficial to remove epiderm, open neck wrinkles;  good dispersing collagenous fiber;  the usage of Na2S = 0.8%, and lime = 3%.
  54. 54. 1 • Brief introduction of China Leather & Footwear Industry Research Institute (CLFI) 2 • Situation of China Leather Industry Development 3 • Pollution Control in Tannery 4 • Clean Production
  55. 55. 4. Pollution Control in Tannery + Water consumption 30~60 m3 Chemicals 500~550kg 1 Tonne Raw Hides 320~350 kg Finished Leather 28~55 m3 Effluent Include: COD 180~220 kg BOD 100 kg SS 125 kg Cr 0.5~0.6 kg S2- 1 kg Wastes from tannery 60~90 kg Sludge from Wastewater 100~135 kg
  56. 56. Quality of influent unit: mg/L 4. Pollution Control in Tannery pH CODCr SS CrTotal S2- N-NH3 8~9 4000~5000 2000~3000 10~15 15~20 50~300 4.1 Quality of Influent
  57. 57. 4. Pollution Control in Tannery Equalization Reaction Settling DAF A/O Treatment Influent Effluent Sludge Activated Sludge recycling 4.2 Typical Treatment Process of WWTP in Tannery Air ChemicalsChemicals Sludge Dewatering Primary treatment Secondary treatment
  58. 58. Note: * indirectly discharge standard (industry area) 4. Pollution Control in Tannery Quality of effluent unit: mg/L pH CODCr BOD5 SS CrTotal S2- N-NH3 6~9 100~500* 30~150* 70~200* 1.5 1.0 15~25* 4.3 Quality of Effluent
  59. 59. 4.4 Individual treatment technology  Unhairing wastewater treatment 4. Pollution Control in Tannery Acidification Reactor Settling Scrubber NaHS Solution H2S Sludge NaOH Unhairing Influent Integrated WWTP Acid
  60. 60. 4. Pollution Control in Tannery 4.4 Individual treatment technology  Chrome-bearing wastewater treatment Reaction Reactor Settling Chrome WW Influent Integrated WWTP Alkali Chrome Sludge
  61. 61. 4. Pollution Control in Tannery 4.5 Tertiary Treatment Technology  RO (Ultrafiltration and Reverse Osmosis) treatment —— for treated water recycling Treated WW could be reused in Tannery
  62. 62. 4. Pollution Control in Tannery 4.5 Tertiary Treatment Technology  Land application (reed, vetiver grass, sedge, water shallot) treatment —— for ammonia and nitrogen removal Reed Yetiver Grass Sedge and Water Shallot
  63. 63. 4. Pollution Control in Tannery 4.5 Tertiary Treatment Technology  Fixed film treatment —— for ammonia and nitrogen removal Nitrifying bacteria was fixed in the film
  64. 64. 4. Pollution Control in Tannery Dewatering Drying Dryed Sludge 4.6 Sludge Treatment  After sludge thickening, sludge is dewatered by pressure filtration, the water content is about 65~75%;  Sludge drying by drying equipment, water content is only about 20~30%;  Steam consumption is: 0.5~0.7m3/ton sludge.
  65. 65. 4. Pollution Control in Tannery
  66. 66. The author thanks China Leather Industry Association and ASSOMAC of Italy. Acknowledgements
  67. 67. Tel: +86-10-6433 7975 Fax: +86-10-6435 1739 E-mail: g_zhongbai@163.com www.clf.cn www.leather365.com

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