Sustainable Development of China Leather Industry

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 Leather Industry
Development
3
• Pollution Control in Tannery
4
• Clean Production

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

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

 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

 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

 more than 160 employees, including 11 Professors,
35 Senior Engineers, 5 Ph.D., 1 Doctoral Supervisor
and 5 advisor of master
1.4 Staffs

 Leather Technologies
 Footwear Technologies
 Chemicals
 Footwear Materials
 Synthetic Leather
 Environmental Protection
 Leather Wastes Recovering and Reusing
1.5 Main Fields of R & D

 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

 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

 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

 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

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

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

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

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 technologies.

 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
Development

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

Development
② Exports
Date Export Value Growth Rate
2010 53.83 billion U.S. dollars +33.8%

Development
③ Imports
Date Imports Value Growth Rate
2010 6.11 billion U.S. dollars +34.0%

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.

2.4 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.
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%.
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.
Development

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)

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

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

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

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)

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%
Cr2O3inWW(mg/L)
Vegetable Tannin Extract
Cr2O3 in WW
Cr2O3 in Leather
Wattle Tara BA
 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.

3. Clean Production
 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%
Cr2O3inWW(mg/L)
Synthetic Tanning Agent
Cr2O3 in WW
Cr2O3 in Leather
OS STF

3. Clean Production
 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

 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

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.

3. Clean Production
Gathering Clearing
Reacting Pressing

3. Clean Production
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.

3. Clean Production
 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 %

3. Clean Production
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

3. Clean Production
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

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.

3. Clean Production
Without heavy metal, easy reuse
Waste
Hydrolysis
by alkaline
Hydrolytic liquor
Industrial protein Gelatin

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

3. Clean Production
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

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%
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.

3. Clean Production
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

3. Clean Production
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.

3. Clean Production
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.

3. Clean Production
Hair
Separator

3. Clean Production
 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.

3. Clean Production
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%.

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

Quality of influent unit: mg/L
pH CODCr SS CrTotal S2- N-NH3
8~9 4000~5000 2000~3000 10~15 15~20 50~300
4.1 Quality of Influent

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

Note: * indirectly discharge standard (industry area)
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

4.4 Individual treatment technology
 Unhairing wastewater treatment
Acidification
Reactor
Settling
Scrubber
NaHS Solution
H2S
Sludge
NaOH
Unhairing
Influent
Integrated
WWTP
Acid

4.4 Individual treatment technology
 Chrome-bearing wastewater treatment
Reaction
Reactor
Settling
Chrome WW
Influent
Integrated
WWTP
Alkali
Chrome
Sludge

4.5 Tertiary Treatment Technology
 RO (Ultrafiltration and Reverse Osmosis) treatment
—— for treated water recycling
Treated WW could
be reused in
Tannery

 Land application (reed, vetiver grass, sedge, water
shallot) treatment —— for ammonia and nitrogen removal
Reed Yetiver Grass Sedge and Water Shallot

 Fixed film treatment —— for ammonia and nitrogen removal
Nitrifying bacteria was fixed in the film

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.

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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