Republic of Ethiopia (2007) EPA Environmental impact assessement guidelines for tanneriesTannery 2007 final

Republic of Ethiopia (2007) EPA Environmental impact assessement guidelines for tanneriesTannery 2007 final


The Federal
Environmental Protection Authority

Environmental impact Assessment Guideline for
Tanneries

NOT FOR CITATION

This guidelines is still under development and shall be binding after
consensus is reached between the Environmental Protection
Authority and the Environmental Units of Competent Sectoral
Agencies

April 2005
Addis Ababa

Ethiopia


The EFDRE Environmental Protection Authority

Acronyms

AOX-Adsorbable Orgainc Halogen

APE-Alkyl Phenol Ethoxylates

EDDS –Ethylene-diamine-Di-Succinate

EDTA- Ethylene-Diamine –Tetra-Acetate

EIA- Environnemental Impact Assessment

EPA-Environmental Protection Authority

EPE-Environmental Policy of Ethiopia

FAO-Food Agricultural Organization

GDP- Gross Domestic Product

HVLP-High Volume Low Pressure

ISO- International Standards Organization

MGDA-Methyl-Glycine-Di-Acetate

NPE-Nonytphenolethoxylaties

NTA-Nitrilo-Tri-Acetate

BAT-Best Available Techniques

EU-European Union

EA-Environmental Assessment

ETP-Effluent Treatment Plant

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Glossary

Aerobic: process involving areas of oxygen.

Anaerobic: process without oxygen.

Asphyxia: is the eventual result of prolonged exposure to an atmosphere containing too little oxygen to

sustain life; many such situations involve the displacement of oxygen-containing air with an asphyxiant

gas.

Assimilative capacity: is the capacity of the natural environment to absorb waste materials without

being affected.

Bating: is the manufacturing step which follows liming and precedes pickling. The purpose of bating is to

declime the hides, reduce swelling, peptize fibres, and remove protein degradation products.

Beam house: is that portion of the tannery where the hides are washed, limed, fleshed and unhaired,

when necessary, prior to the tanning process.

Biochemical Oxygen Demand (BOD): is a measure of the quantity of oxygen which may be consumed

while biologically degrading the organic constituents. The test is carried out over five days and the result

expressed as BOD5.

Chemical Oxygen Demand (COD): is a measure of the quantity of oxygen consumed during chemical

oxidation of the constituents of an effluent with potassium dichromate.

Deliming: is the process which removes the lime from hides coming from the beamhouse.

Disposal: is the act of discharging a waste or effluent into the environment.

Environmental standard: is a legal level of a pollutant set by regulation.

Eutrophication: is the nutrient enrichment of natural waterbodies leading to excessive growth of algae

and weeds so as to ultimately choke the normal aquatic life processes.

Finishing: is the final set of processing steps performed on a tanned hide. These operations follow the

retain-colour-fatliquor processes, and include the many dry processes involved in converting the hide into

the final tannery product.

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http://en.wikipedia.org/wiki/Asphyxiant_gas
http://en.wikipedia.org/wiki/Asphyxiant_gas
http://en.wikipedia.org/wiki/Oxygen


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Full chrome: is used to refer to a tannery process. "Full" is sometimes added to the term "chrome

tanned" to emphasize that the leather has not been tanned by the semi-chrome or combination chrome

processes.

Grain: can mean:

a) the outer, or hair side, of a hide or skin that has been split into layers; or

b) the pattern visible on the outer surface of a hide or skin after the hair or wool has been removed.

Leather: is a general term for hide or skin which still retains its original fibrous structure more or less

intact, and which has been treated so as to be non-putrescible even after treatment with water.

Pickling: is the process that follows bating, whereby the skin or hide is immersed in a brine and acid

solution to bring it to an acid condition. It prevents precipitation of chromium salts on the hide.

Pollution: is a state that occurs when assimilative capacity of the environment is exceeded, resulting in

illness or death of organisms, and undesirable ecological changes.

Retaining: is the process of subjecting a skin, which has been first more or less completely tanned by

one process or one kind or blend of tanning materials, to a second tanning process involving similar or,

more usually, different tanning materials.

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1 Introduction and Background

1.1. The Ethiopian economy is dominated by agriculture, which accounts for about 50% of the total,
and 90% of the export and 85% of the total employment. Similarly, the industrial sector is
basically dominated by agro industries that contribute about 12% to the GDP. This sector
supplies important consumer’s goods both to domestic and external markets.

1.2 Leather and leather products are among the main manufacturing export products. Within the
manufacturing sectors, the leather industry comes as the leading exporter and accounting for up
to 67% of the total manufactured exports. The leather industry is one of the many economic
sectors, which the government has given due consideration for the development. The country
was able to generate above US$60million.in the year 2004 from its leather industry.

1.3. Ethiopia possesses 12, 15 and 22 percent of the world cattle, sheep and goats population
respectively. This showed that, the country is one of the most promising leather producing
country in Africa. The report issued by the Ministry of Agriculture and Rural Development
indicated that from its cattle resources Ethiopia is able to produce about 2.4 million of hides 8.3
million ship skins, 7 million goat skins annually.

1.4 Currently there are 20 tanneries, which are operational in this sector employing about 6000
workers. The current production capacity based on 15 tanneries is estimated at 6,000,000 to
8,000 000 kilograms of hides and 20, 000, 000 to 25,000,000 skins. The hides are processed up
to wet blues, crust and finished leather. The wet blues and crust hides are produced for export
and the remaining low quality are finished for local market in the form of garments uppers and
linings.

1.5. However, the industrial establishments huge potential of for sustained economic development of
the country has been constrained for they were not designed and operated in sustainable
manner for some time now. In Ethiopia, the annual volume of liquid waste discharge from the 15
tanneries based on their annual production capacities is estimated to vary between 2,000,000
and 2,500,000 cubic meters.

The major features of Ethiopian Industries thus include among other things that, they:
o are based on obsolete technologies;

o were operating in the absence of appropriate environmental laws and standards as well
as low level of environmental awareness,

o did not subject to impact assessment process;

o are not located in well defined industrial zones and concentrated in urban centres along
multipurpose rivers and streams;

o Most of tanneries do not have treatment facilities and environmental management
systems, as a result simply discharging their wastes into the environment; etc.

1.6. Thus, are causing serious environmental and public health problems in particular in urban
centres. It is obvious that the effect will further extend to rural areas as well. Besides, the loss of
economic benefits that could have been derived from this sector, cannot survive a growing
challenge of environmentally sound competitive business unless appropriate environmental
management system is introduced.

1.7. It is therefore essential to change this situation by introducing a system that helps improve the
environmental performance and consequently the productivity of our tanneries. The objectives of
this guideline are therefore:

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(i) Major Objective (Over all objective?? )

 To ensure the sustainability of Tanneries development in Ethiopia.

(ii) Specific Objectives

 to provide guidance for undertaking environmental impact assessment of tannery
developments,

 guide people on safe production, use, handling of tanneries products; and managing adverse
impacts and enhancing positive ones in a manner that add competitive value to tanneries
business.

 help enforce Environmental Policy of Ethiopia and applicable environmental legislations and
standards,

1.8. This, guidelines is prepared mainly to assist EA practitioners, proponents and, regulators. In
addition individual researchers and other interested persons can be made use of it.

2 Legal, Institutional and policy Frameworks

2.1 Legal frame work

2.1.1 The Constitution of the Federal Democratic Republic of Ethiopia

The constitution stipulates that the government shall endeavour to ensure a clean and healthy
environment as an objective and recognizes the right to a clean and healthy environment as a basic right
of the Ethiopian people (Art 92.1 and 44.1, respectively).

It also stipulates that the design and implementation of development programs and projects should not
damage or destroy the environment (Art 92.2).

Tanneries development thus has to be guided by these constitutional orders.

2.1.2 Environmental proclamations

To enforce the aforementioned constitutional provisions and give guidance as to positively influence the
design and implementation of various developments, a number of environmental proclamations have
been proclaimed. Accordingly, development initiatives in the tanneries sub sector are required to review
these and other applicable proclamations and environmental standards so as to abide and take the
appropriate measures. Major features of some of them are highlighted in brief below.

 Environnemental impact Assessment proclamation (Proclamation No 299/2002)

This proclamation requires that major development programme; plans and projects of the private
and public sectors are subject to EIA before their approval. This proclamation also provides a
legal base to harmonize and integrate environmental economic, cultural and social
considerations into the planning and decision making process and there by promotes sustainable
development. It also states a number of obligations, including that specifies the contents of the
report and factors for the determination of impacts, among other things.

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 Environnemental Pollution Control Proclamation (No 300/2002)

This proclamation provides framework or general rules to control environmental pollution from all
kinds of sources. As a general principle the proclamation prohibits pollution of the environment
from any source by any person violating the relevant environmental standard. It is guided by the
precautionary and the polluters pay principles as well as the use of” sound technology “in
controlling pollution.

In addition any person who wish to engage in tannery development is required to review relevant
sectors legislation, namely labour proclamation (No 377/2002), public health proclamation (No
200/2002) water resources proclamation (No, 197/ 2000) etc in conjunction with federal and
regional environmental legal requirements, procedures, guidelines, etc.

 Industrial Pollution Prevention and Control Regulation(Draft)

The draft industrial pollution regulation, which is excepted to be issued recently provides general
obligations to be observed by industries .It also provides the authority and competent
environmental agencies with the issuance condition and suspension or pursuant grants to these
regulations

 Provisional standards for industrial pollution control in Ethiopia (2003)

This standard among other things provides guidance on effluent and emission standards. Annex
3) emission and effluents standards for tannery).

2.2 Institutional framework

 Environmental Protection Organ Establishment No. 295 of 2002

The cardinal factor that stipulates the issuance of the proclamation is to provide an effective and
differentiated but collaborated institutional arrangement that is required to ensure environmental
development and protection on sustainable basis.

According to this proclamation the Environmental Protection Authority is established with the objective to
formulate policies, strategies, laws and standards, which can foster sustainable development, and
spearheads as well as monitor their proper implementation.

The Proclamation has also provided for the establishment of Regional Environmental Agencies and
Sectoral Environmental Units.

The main implication regarding institutional issues is to put in place appropriate environmental unit (EU)
at industry level. This unit should establish functional linkage with appropriate bodies, oversee the
companies environmental performance, adherence to various environmental requirements and work with
all stakeholders with spirit of collaboration, and responsibility for environmental good governance.

2.3 Frame Work Policies

 Environmental Policy of Ethiopia

The country has approved an environmental policy in 1997. Overall policy goal is to promote sustainable
development through the sound management and use of resources. So as to meet the needs of the
present generation without compromising the ability of future generations to meet their own needs

Environmental Policy Ethiopia (EPE) contains several pertinent policy elements related to industrial
pollution prevention and control. The policy radiates the two basic principles applicable to pollution
control, namely, the “polluter pays principle” and the “precautionary principle”. It also provides for the

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adoption of cost effective environmental standards and the establishment of a system for monitoring
compliance of the standards. The policy further stipulates for the promotion of waste minimization
processes, including the efficient recycling of materials.

 Other policies
The Health (Sep.1993) and Water Resources policies have also required prevention of wastes, proper
management, and protection of aquatic bodies from pollution. Effort should be exerted to closely study
these and other policies in the course of assessment, design and implementation of tannery
development.

3 Tanning Process

3.1 What is Tanning?

Tanning is a process of converting putrescible animal hides and skins to a stable commercial product
called Leather. Before the tanning process, curd hides and skins arriving at a tannery are trimmed to
remove long shanks and unwanted materials for leather making. Then the soaking, liming, fleshing, de-
liming, bating degreasing and pickling processes are carried out to create a conductive situation for
tanning process.

3.2 Major operations

The production processes in a tannery can be split into four main categories.

3.2.1 Hide and skin storage and beam house operations

Hides are prepared for tanning by cleaning and conditioning and by ensuring the correct
moisture. The following processes are typically carried out in the beam house of a tannery.

a) Soaking

The main purpose of soaking is to re-hydrate the hides/ skins ready for subsequent processing, and to
remove the salt.

 Soaking may be carried out in pit, paddle or drum (or a combination of these) or re-hydrate
the skin and reverse the cure process.

 Dirt, blood and dung of may also be removed.
 Chemicals that can be used for this process include sodium-hypochlorite and /or wetting

agent, emulsifiers, surfactants and enzyme preparations.

b) Liming and unhearing
 This stages removes:-

 Hair and epidermis, and
 further reduces the content of non-collagenous proteins,

A significant proportion of organic pollution is derived from the degraded keratin comprising the hair and
epidermis.

Lime blended with sodium Sulphide as traditionally used to loosen wool and hair or dissolved these into
pulp. The duration of the process may vary from 18 hours (drums) 7 days (pit). This process is
responsible for the major part of COD Load form tannery. Chemicals include calcium hydroxide (2-10%),
(lime), sodium sulphide (1-4%), sodium and sulphydriate, caustic soda, Dimenthylamine sulphate is too
toxic to be recommended.

c) Fleshing and/or splitting

The flesh side of hides /skins still can have excess fat, flesh and connective tissue attached, which must
be removed prior to further processing .The hides/skins are individually fed through a fleshing machine

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consisting of a set of revolving cylinders designated to cut and scrape away the unwanted material .As
the fleshed hides exit the rear of the machine, some of the rough edges are cut off, producing further
waste in the form limed trimmings. (See UNEP-guide Page 17)

3.2.2 Tan yard process

Typically, the following processes are carried out in the Tanyard:-

a) Deliming and Bating
The lime in the pelts is no longer required and must be removed to avoid interference with subsequent
tanning and stage, which occurs in acide solution such process is called Deliming. Deliming using
ammonium salts carries out-reduction in the pH of the pelts first. Bathing is performed in the same delime
float and uses enzymes to break down the unwanted protein.

b) Pickling
After bating, pelts are pre-treated by “pickling “in salt and Sulphuric acid to prevent precipitation of
chrome salts prior to their addition.

c) Tanning
Tanning processes mainly used for hides or sheep/goat skins include:

- Chrome Tanning
The majority of leathers today are chrome tanned in drums from 4 to 24 hours.

chemicals include: 8-12% pelt weight of chrome tanning salt, and as little as 5-6% for low chrome
processes (basic tri-valiant chromium sulphate hydrated complexes) (22-25% Cr2O3 ) I.0% sodium
bicarbonate (basifying agent to adjust pH), o.I-o.5% masking agent-sodium formate, phthalate or salts of
dicarboxylic acids, o.I fungicide if product is to be stored/transported in wet blue condition.

- Vegetable Tanning
While vegetable tannage has been eclipsed by chromium as the major tanning process, it is still
employed for sole saddlery and some specialty leathers. It may also be used as part of a combination
process. duration of the process is from I day (drum) to 6 weeks (pit).

Substances used are typically 15-30% of commercial tanning extract (bark or wood of tree, aqueously
extracted), often sulphitated, then spray dried or concentrated.

3.2.3 Post-tanning Wet Work

This involves further processing of the stabilized collagen network and may comprise a further tannage
(e.g. with combinations of chrome, vegetable, glutaraldehyde or syntan agent) when special
characteristics such as perspiration resistance are required. Conditioning softening, dyeing or bleaching
may also be carried out.

Few solid wastes are produced, and the aqueous effluents do not generally contribute significantly to the
overall load of pollutants from the tannery.

3.2.4 Drying and Finishing

The leathers are sammied to remove moisture, and then dried. The final finishing process includes
mechanical treatment of grain and flesh, followed by application of surface finish.

The surface coatings consist of dyes or pigments dispersed in a binder, typically casein or an acrylic or
polyurethane polymer, and are applied by padding, spraying or rolling. Nitrocellulose lacquer or urethane
lacquer may be applied with organic solvents as top coats. Non-solvent based finishing process are
rapidly increasing in use, either through the substitution of aqueous solvents or elimination use of
Benzedine dyes, if still occur rings, should be discontinued due to the toxicity of these substances. .

The major environmental problem in finishing is undoubtedly air emission of solvents. Some aqueous
waters may be generated. Solid wastes may arise from trimmings and buffing dust.

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Finishing

Wetblue:

Chromium tanned hides are often retanned - during which process the desirable properties of more than
one tanning agent are combined and treated with dye and fat to obtain the proper filling, smoothness and
colour. Before actual drying is allowed to take place, the surplus water is removed to make the hides
suitable for splitting and shaving. Splitting and shaving is done to obtain the desired thickness of the hide.
The most common way of drying is vacuum drying. Cooling water used in this process is usually
circulated and is not contaminated.

Crust:

The crust that results after retanning and drying, is subjected to a number of finishing operations. The
purpose of these operations is to make the hide softer and to mask small mistakes. The hide is treated
with an organic solvent or water based dye and varnish. The finished end product has between 66 and
85 weight percent of dry matter.

A more detailed description of the tanning process is found in the publication “Animal by-product
processing” by Ockerman and Hansen, 1988.

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Figure 1 schematic of tanning process, indicating waste stream.---

Water Polluants Air polluants
Solid wastes

BOD, COD, SS,
DS, salts, Organic N

Green flashings (fat
Containing organic matter)

BOD, COD, SS
DS, alkalinity H2S
Sulphides, Organic N Hair, lime, and organic
ammonia N matter containing sludge

Lime fleshings (fat containing
BOD, COD, SS, Ds,limed organic matter)
alkalinity

Lime split and trimmings
(limed organic matter)

BOD, COD, DS,
ammonia N NH3

BOD, COD, DS,
fat

BOD, COD, SS,
DS, acidity, salts
chrome, vegetable
tans, syntans,
salts Chrome split (chrome-containing

organic matter)

Shavings (chrome-containing
organic matter)

BOD, COD, DS
chrome, vegetable
tans, syntans,
dyes, fats

Chrome trimmings (chrome and
Prefinishing chemicals containing

Remainder Organic matter)
of finishing Solvents, formaldehyde

agents
.

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Raw
Hide
s

Soaking

Green Fleshing

Unhearing, Liming

Lime fleshing

Lime splitting
Trimming

Finishing

Batting
Trimming

Drying

Retanning
Dyeing

Fat liquoring

Shaving

Chrome
splitting

Pickiling
Tanning

Degreasing,
(Sheep-pigskins)

Deliming, Bating

Leathe
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3.3 Impacts of Tanning Industry on the Environment

There are some positive and negative impacts from the tanning industry.
Positive impact:-

 Generation of employment opportunity:
 Economic gain through export market and
 Local market opportunity from the sell of hides and skins

Negative impact:-
The main sources off negative impacts are chemicals used for tanning processes.The tanning industry
gives rise to two types of hazard involving chemicals. These are, firstly, those concerning particular
chemicals used in the various tanning processes, and secondly, chemical substances produced as by-
products by the chemical reactions occurring when a hide undergoes the tanning process.

 The first type of hazard includes the vast majority of chemicals to be found in tanning. It is
possible to divide these materials into groups based either on the particular degree of hazard
they present, or on their chemical nature (e.g. acids, alkalis, etc.).

 A chemical hazard to workers e.g hydrogen supplied

In terms of toxicity and potential to cause a hazard it is a relatively straight forward task to divide a typical
list of chemicals used in tanning into three groups representing major, moderate, and minor potential
hazards. See annex 1
Also tanning produces hazardous chemical by-products which can be categorized into three general
areas. See annex 2

Tanning and its associated operation while using the different chemicals pointed out in the previous
paragraphs can be source of considerable negative environmental impacts. The impacts include-:

 Air , water and land pollution,
 Human health and occupational safety,
 Loss of economic benefits
 Damages the ecological processes

3.3.1 Impact on Air, Water and Land

Tanning generated wastes can cause environmental pollution in different environmental mediums. The
following table presents some pollutants that would cause negative impacts on air, water and land.

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Table 1 POLLUTANTS AND ITS NEGATIVE EFFECT

Pollutants Symbol Main Negative Effects Impact medium
Ammonia NH3 Pungent odour and adverse effects on aquatic life like fish Water& Air
Total Kjeldahl
Nitrogen

TKN
Causes excessive plant growth and formulation of algae
cause eutrophication and reduction of oxygen

Water

Trivalent
Chrome

CR III
Toxic to human, aquatic life and crops
At high temperature oxidizes to chrome VI, which is highly
toxic

Water & Land

Chloride Cl
Harmful to plants and agriculture, corrodes metal and
piping in civil construction

Water & Land

Biochemical
Oxygen
Demand
(Winkler)

BOD5
BODs indicates the quantity of oxygen may be consumed
while biologically degrading the organic constitute.

Water

Chemical
Oxygen demand
(Dichromate)

COD CODs- is measure of oxygen consumed during chemical
oxidation of the constituents of effluents.

Water

Total Dissolved
Solids,
Sulphates &
Chlorides

TDS
CL-
SO4

Harmful to plants and civil structures
Unfit for human, industrial and agricultural use
High salinity cause osmotic pressure (reduced water
availability and retarded plant growth
High concentrations of sodium ions in irrigation water
affect the soil structure and properties by causing
dispersion of clay

Water & Land

Oil & Grease O&G
Forms surface films on water and shoreline deposits which
lead to environmental degradation and interfere with
biological processes

Water & Land

PH PH
Acidic conditions cause concreter and metal corrosion and
are toxic to aquatic life
High alkaline conditions are toxic

Water & Land

Suspended
Solids

Suspended
Solids

Can form deposits and create anaerobic condition (odour)
which pose a danger to aquatic life

Water

Sulphide S2−
Odour nuisance at low levels and fatal in high
concentrations
Poisonous to aquatic life, depletes dissolved oxygen
damages sewerage systems

Water & Air

Sulphate
SO4 May cause corrosion of concrete and piping and limits the

use of the water bodies for both human and agriculture
In anaerobic conditions, can be converted sulphides.

Water & Land

Note: One tone of raw hide converted into about 200 kgs of finished leather the remaining 800 kgs is
waste or pollution.

3.3.2 Impact on human health and occupational safety due to exposure to hazardous chemical

 The impact of exposure to hazardous material and waste, which emanates from tanning
process include: such as:

 dizziness,
 headache,
 Irritation eyes, skins
 Allergic
 Collapse due to lack of oxygen
 Bronchitis
 In some rare case even cause death

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4 Hazards related to tannery workers

The leather industry and in particular tanning processes are notorious for their deleterious environmental
impacts and occupational health hazards. Working at tanneries involve a series of hazardous processes
is presented in Table-2.

Table-2 Hazards related to tannery workers
Physical Hazards  Exposure to high noise levels from mechanical equipment.

 

 Callosities on hands caused by continuous work with hand tools
 

Eye stain due to poor illumination in the tannery.
 

Chemical Hazards Skin rashes and dermatoses as a result of exposure to cleaners,
solvents, disinfectants, pesticides, leather-processing chemicals etc.
 

Allergies-contact and systemic-caused by many of the chemicals
used in tanneries.
 

Biological hazards Raw hides and skins may be contaminated with a variety of bacteria,
molds, yeasts, etc and various diseases (e.g., anthrax, leptospirosis,
tetanus, Q-fever, brucellosis, etc.) also the large quantities of dust
produced in buffing operations would normally be contaminated with
disease-bearing microorganisms, etc.
 

Ergonomic,
psychosocial and
organizational
factors

Acute musculoskeletal injuries caused by physical overexertion and
awkward posture while moving heavy or bulky loads, in particular
bundles of hides, skins and leather.
 

Low back pain due to prolonged working in a standing or semi-
bending posture
 

Heat stress, in particular when working on warm days in premises
lacking good ventilation or air conditioning.
 

Accident hazards Slippery floors, while moving heavy loads such as containers of
chemicals, bundles or hides, skin, leather, etc.
 

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Electric shocks caused by contact with defective electric machinery
 

Blows and crushing injuries caused by rotating or moving parts of
machinery
 

Acute poising and/or chemical burns by inhalation, ingestion or skin
contact with constituents of tanning process liquors, or poisonous
gases released during the tanning process (e.g., hydrogen sulfide)
 

Burns caused by contact with hot surfaces or splashed of hot
solutions
 

Cuts and stabs caused by manual or mechanized working tools
 

Eye injuries caused by flying particles from rotary buffing
machines 
 

Asphyxiation or poising in confined spaces, in particular during the
cleaning of vats or tanning baths
 

The employer or the tannery manager is responsible for his workers’ safety. The employer has the
obligation to communicate potential hazard information to the workers in such a way that they can
understand and are able to avoid the hazards in question. The employer also has the obligation to
provide safety equipments to works so that they can be protected from the likely impact in the tanning
process.

It is necessary that all workers in the tanning operation have adequate awareness and knowledge about
the different kinds of chemicals, their hazardous status etc. One-way of providing a safety and
precautionary measures is to use the most common labels for chemicals in a tannery. These are:

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Fig. 2 Categories of Dangerous Chemicals

The classification is normally presented in the form of an abbreviation representing the category of
danger together with the appropriate risk phrase or phrases. However, in some cases (i.e. substances
classified as flammable, sensitizing and some substances classified as dangerous for the environment)
the risk phrase alone is used. The abbreviation for each of the categories of danger is shown below:
Explosive:

 Oxidizing: O
 Extremely flammable: F+
 Highly flammable: F
 Flammable: R 10 (without symbol)
 Very toxic: T+
 Toxic: T
 Harmful: Xn
 Corrosive: C
 Irritant: Xi
 Dangerous for the Environment: N

 Prevention of chemical hazards to workers

To handle these hazardous chemicals it is necessary to have / to follow the following procedures:-

 Material safety data sheets
 Labels on chemicals containers that show chemical danger
 Store chemical safely

Material Safety Data Sheets (MSDS)
MSDS are designed to communicate hazard information to the user and public and avoiding any risk to
the worker and the environment. EU Commission Directive 93/112/EC of 10 December 1993 defines and
lays down detailed arrangements for the system of specific information relating to dangerous substances.
The MSDS is divided into 16 sections as follows:

 Chemical product & company information
 Composition/information on ingredients
 Hazards identification
 First aid measures

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 Fire fighting measures
 Accidental release measures
 Handling and storage
 Exposure controls/personal protection
 Physical and chemical properties
 Stability and reactivity
 Toxicological information
 Ecological information
 Disposal considerations
 Transport information
 Regulatory information
 Other information like transport requirements

The information in the MSDS is the summary of facts from many sources

Labelling procedure

 Labels should specifically indicates:

 Trade or brand Name,

 Ingredient statement,

 Common or chemical name,

 Type of formulation,

 Net content of the package,

 Name and address of manufacturer, distributor,

 Registration or license number,

 Warning or signal words,

 Hazards to humans and domestic animals,

 Environmental hazards,

 Physical and chemical hazards,

 Statement of practical first aid treatment,

 Re-entry statement,

 Storage and disposal directions,

 Warranty statement,

Note must be attached to or printed on the side of the container in both English and the official local

languages

Store chemical safely

 Ensure proper lay out of chemical store,

 Fire extinguishers should be placed outside store,

 Smoking and use of open fire is prohibited,

 Shower should be available in or near chemical store,

The following basic rules and principles should be used to store chemical safely

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Storage requirements

 All chemical storage areas must be securely fenced to prevent unauthorized access,

 All doors and gates should be efficiently locked or padlocked,

 In case of fire, the address of the person(s) holding the keys should be fixed to the gate

or door, etc.

 The building:

 Should be constructed of fire-resistant materials such as concrete block or metal,

 Should be well ventilated preferably by natural wind flow to minimize temperature

increases and keep fumes from accumulating,

 Should be surrounded by a ditch to keep any liquid spills from draining away,

 Should be constructed to allow tight security. (Locking doors, barred windows),

 Should be well lit by sunlight or electric lights,

 Have a water supply for spill decontamination, etc.

 Managing chemical stores:

 “First in first out” procedure should be followed to minimize the deterioration of

chemicals and containers,

 Different types of chemicals should be stored separately to prevent possible cross-

contamination.,

 No food, drink or animal feed should be stored in chemical store,

 Protective clothing should not be stored in the same room with chemicals

 All chemicals should be labelled, etc.

Health and Safety Measures

After understanding the label directions, make certain you have taken the following precautions:

 Have detergent or soap and an adequate supply of water available,

 Know the early symptoms of poisoning for the chemicals you are using,

 Know the first aid procedures and make certain that materials and supplies are available,

 Be certain that materials are available to handle spills,

 Make certain that all equipment is functioning properly,

 Do not work alone; be sure help is available if you get into trouble,

 Have all the recommended protective clothing and equipment.

 Double-check that the respirator fits properly and has the correct canister cartridge,

 Never eat, drink, smoke, or go the bathroom while working with chemicals without first

washing your hands,

 Improve working environment

 During the production of leather the process on machines and the

chemicals reactions involve emission of heat, dust, gases vapors, noise

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vibration to which workers are exposed daily. It is therefore necessary

to:

 Control temperature and humidity through natural and artificial ventilation.

 Insulate against heat and cold

 Ensure quality of light

 Reduces the overall noise level

Personal protective equipment

 The most commonly needed personal protective equipment in tanneries and effluent

treatment plants are ;-

 Protective clothing (gloves, safety shoes/boots ,aprons)

 Hearing protection

 Protective goggles and shields and

 Respirators

Disposal

Products that cannot be used for their intended purpose (s) or permitted alternatives, and that cannot be

reformulated to become useable again, should be considered for disposal.

The basic procedure for the disposal are the following;-

 Remove empty chemical containers from the store and work areas.
 Don’t pour or mix different waste chemicals in the same waste container or barrel
 Disposal should be made based on study, in approved place and acceptable conditions.

5 THE NEED FOR POLLUTION CONTROL

Defining Pollution Prevention

Pollution prevention (P2) is the reduction or elimination of wastes and pollutants at their sources. For all
the pollution that is avoided in the first place, there is that much less pollution to manage, treats, disposes
of, or cleanup. P2 can encompass activities such as:

 redesigning products to cause less waste or pollution during manufacture, use, or disposal
 altering production processes to minimize the use of toxic chemicals
 implementing better housekeeping practices to minimize leaks and fugitive releases from

manufacturing processes taking steps to reduce energy consumption

5.1 Basic waste management hierarchy

In order to minimize the negative impacts emanates from tanning industry ,fundamental pollution control
practices have to be implemented .The generally accepted waste management hierarchy include
waste:-

 Prevention and Reduction
 Recycling and Reuse
 Treatment and
 Disposal

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Fig 3- Pollution Prevention HIERARCHY

One of the main principles mentioned in our Environmental policy is pollution prevention.
The main reasons for exercising pollution prevention are to:

 Protect the environment;
 Safeguard human health;
 Create sustainable development and economic benefits of the tanning industry.
 Normalize the opposition of peoples who are living nearby against the released waste.
 To produce ecologically sounding product and to get acceptance in the market.
 For the ease of certification of environmental management system.

 Waste reduction at source
Example

o Timely repair/sealing of water and steam leakages from pipes, valves, flanges, etc
-keep taps close when not in use
-control of leakages and spillages in the handling and preparation of chemicals and

additives
-Avoid Spillage
-segregate the line of alkaline from acidic
-Reduce material handling losses,
-proper maintenance and operations of equipment
-By changing process

 Recycling, Reuse, Recovery and uses of unnecessary discharges water stream
 Recovery and reuse onsite
Example:

o Recycle back used water.
o Lime sulphide recovery from waste sulphide liquor.
o Chrome recovery from waste tanning liquor.
o condensate recovery and reuse in boiler houses

 Creation useful by products
Example:

o manufacturing of glue from lime trimmings
o Manufacturing of leather board from shaving dusts.
o Conversion of splits to high valuable product etc.

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 By changing in put raw material
Example:

o Using fresh hides and skin than salted hides and skins to avoid salt for
preservations etc.

o use non-toxic materials
o equipment modifications
o install efficient equipment

 Technology change
Example:

o CO2 deliming
o using short float for the reduction of water consumption
o improve chemical uptake by the leather
o use alternative technology for waste minimization
o avoidance toxic and Hazardous Chemicals
o Using of water base degreaser, liquor etc.

Fig 4. Pollutant and their management flow chart

 By product modification
Example

o production of chrome free leather
o produce ecologically sustainable leather

In addition to those mentioned above the following are to be considered. See annex 3

6 Treatment

GENERAL PRINCIPLES

Some basic data must be investigated and defined for designing and ETP.

o Tannery production and capacity:

- Raw material, processing system (with particular attention to the unhearing and tanning
phases), and final product.

- Quantity of the processed material (present and future) as kg or number of hides or skins
processed pre day.

- Eventual (possible) internal recycles or recovery.

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- Water consumption.

o Factory location:

- Industrial rural or residential zone.
- Area available for the ETP.

o Discharge standards

- Limits to discharge, or (in absence) type of recipient and its characteristics (e.g., surface
waters or sewer). In the future the current limits could be subject to change for
magnitude or new parameters under control. Therefore the plant must be flexible and
expandable for complying with new stricter impositions. To respect this condition is not
always easy, but, as a principle, extra space for future extension should be considered in
the ETP layout.

o Some common errors done in the project data collection and ETP design are:-

- Incorrect estimate of the water consumption

The water consumption expressed in L/kg of raw material (green or wet salted weight) should not
differ too much from the following values:

Raw material water consumption (*)
Hides (chrome tanning) 25-40
Hides(vegetable tanning) 20-30
Skins (mixed tanning) 30-60
Skins (fur) 50-100

 Criteria for selecting the effluent treatment

The tannery effluents are characterized by:-
o Intermittent flow,
o Wide fluctuation in pH (from 3 to 12)
o Big variations in the type and load of pollution (both organic and inorganic).

For achieving the common standards for the discharge into surface waters tannery effluents must
undergo a two steps treatment: primary and secondary. By the term “primary” those physical –chemical
treatment are meant which precede the biological (secondary) treatment. Only in case of discharge into
municipal sewer sometimes the installation of the primary treatment alone may be sufficient.

 The primary treatment has the following main aims:

o Eliminate the coarse materials as well as abrasives (sand) that can cause clogging or
damage to the pipes and pumps;

o Transform the tannery wastes (which are extremely variable in quantity and quality) into a
uniform effluent that can be treated in a constant /uniform manner;

o Neutralize too high or low pH values, and eliminate potentially toxic substances (especially
sulphide) that may affect the proper functioning of the biological treatment;

o Reduce the organic load (BOD and COD) and eliminate most of the inorganic suspended
solids in order to reduce the treatment costs and simplify the biological process.

 Treatment options
The choice therefore is on a technical nature but costs are also involved: on the one hand the primary
treatment must guarantee an effluent suitable for secondary one, on the other the same secondary
treatment may be designed for greater or lesser efficiency. High efficient primary treatments greatly
increase the volume of generated sludge and associated disposal costs. For this reason the present
trend is to simplify to the maximum the primary phase, confiding in the secondary one for the main
treatment of the tannery effluent.

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In some cases a totally biological process could be designed, possibly proceeded by chrome
segregation and precipitation, and sulphides oxidation. In general the implementation of a two-phases
1ETP (physical-chemical and biological), allowing adaptation of the primary to the secondary, and
vice-versa, is preferable.

 Other factors are important for selecting the most appropriate treatment method.

o Area availability that allows extended treatment or forces to more compact systems.
o Factory location. Because of the risk of bad-smell and unpleasant sight, certain systems (e.g.,

ponding/ lagooning of water or sludge, sludge drying beds, etc.) are viable only in areas located
far from residential zones.

o The local climate plays an important role in the choice of treatment. Temperature affects the
efficiency and performances of the biological process and rain fall the performance and feasibility
of natural drying system for sludge, e.g., sand-bed

o The tannery production, type of raw material (haired hide, wet-blue or crust), processing method
(mainly chrome or vegetable tanning, and pulp or save hair removal) influence the type of the
necessary treatment. The same effluent volume may affect the type of treatment: the scale of the
tannery could recommend more sophisticated and mechanized solution or justify simpler and
manual alternative

 The characteristics of the final recipient body:

o Rivers and other surface waters usually require the highest quality discharge standards, but
sometimes the high dilution capacity of the recipient could permit more tolerant standards.
Similar standards are usually required for rivers and lakes, but because of the eutrophuy risk in
the second case stricter standards are imposed for phosphorus and Nitrogen.

o Municipal sewer: the discharge into sewers combined to a treatment plant must respect the limits
imposed by the local municipality. The limits refer to some parameters: pH, coarse and settle
able solid, sulphide, and trivalent Chrome. Sometimes also BOD and COD are indicated, but
usually these parameters only affect the tariff charged by the municipality for the treatment
service.
Draft effluent and emission limits value for discharge to water from tannery See annex 5

6.1 ALTERNATIVE TECHNIQUES

In order to minimize the effect of pollution from tanning process different alternative techniques could be
used. These include measures such as, Cleaner Production (CP), Best Available Techniques (BAT) and
Environmental Audit etc.

 Cleaner Production Definition

“Cleaner production is the continuous improvement of industrial processes, products and services to
reduce the use of natural resources, to prevent-at the source-the pollution of air, water and land and to
reduce waste generation-at the source – in order to minimize risks to human population and the
environment” (UNEP 1994). (See Annex 3&4)

1

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Best Available Techniques
Best Available Techniques(BAT)- is defined as “the most effective and advanced stage in the development
activities and their methods of operation which indicates the practical suitability of particular techniques for
providing in principle the basis for emission limit value designed to ,prevent and ,where it is not
practicable ,generally reduce emissions and the impact on the environment as whole.”(See annexes 6-9)

Environmental audit
Environmental management system audit –a systematic and documented verification process objectively
obtaining and evaluating evidence to determine weather an organization’s environmental management
system conforms to the environment management system audit criteria set by the organization, and for
communication of the result of this process to management. For environmental management system
requirement see annex 10


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ANNEXES

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Annex 1

 CHEMICALS USED IN TANNING PROCESSES(Annex 1)

 High Potential Hazard Group
Under this heading the following chemicals can be listed:

 acetic acid hydrogen peroxide
 ammonia oxalic acid
 (slaked lime, lime) sodium chlorite
 calcium hydroxide sodium hydroxide (caustic soda)
 formaldehyde sulphuric acid
 formic acid sulphides and hydrosulphides
 glutaraldehyde hydrochloric acid (e.g. sodium sulphide, sodium
 (muriatic acid, spirits of salts) hydrosulphide, calcium hydrosulphide)

 Moderate Potential Hazard Group
The chemicals listed under this heading include:

 aluminium sulphate
 amyl acetate (as lacquer constituents)
 amyl alcohol (as lacquer constituents)
 benzyl alcohol (lacquer solvent) carbon black
 chromium salts (trivalent) enzymes
 isopropyl alcohol perchloroethylene toluene
 white spirit

 Low Potential Hazard Group
A third hazard category includes those or negligible hazards:

 alums oils
 acetone paraffin
 albumen pigment dispersions
 ammonium chloride sequestering agents
 ammonium sulphate silicones
 borax, boric acid sodium acetate
 casein sodium bicarbonate
 calcium chloride sodium citrate
 castor oil china clay sodium carbonate
 ethanol (ethyl alcohol) sodium formate
 fat liquors sodium metabisulphite
 fats sodium nitrite
 ferrous acetate sodium phthalate
 ferrous sulphate sodium sulphite
 gelatine sodium thiosulphate
 glues (for some glues, solvent synthetic tannins
 may contribute to toxicity) tragacanth
 lactic acid titanium salts
 lanoline vegetable tanning extracts
 lecithin waxes
 wetting agents

 Miscellaneous Hazards Group
Because of wide variations in potential toxic hazard it is not possible to
categorise dyestuffs or fungicides into any one hazard group.
 Dyestuffs
These may vary widely in toxicity from potentially quite serious if inhaled or
ingested, to non-toxic.
 Fungicides
Tanneries use several biologically active chemicals to control the growth of various forms of fungal life on
the leather (e.g. “TriNap 40”). These should all be handled with caution to prevent contact with the skin,
inhalation or ingestion by workers

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Annex 2

 HAZARDS RESULTING FROM BY-PRODUCTS OF TANNING PROCESSES

 Gaseous emissions within the tannery- during processing; the most important in-plant
pollutant is hydrogen sulphide, and ammonia may also present problems.

 Effluent outside the Tannery- The other two areas are those of liquid and solid effluent which
are removed by normal drainage systems, and the release of gaseous wastes into the
atmosphere. Each of these results in a problem outside the confines of the factory itself and in
terms of legislative responsibility the onus rests with agencies other than the Department of
Labour, which under the Factories Act can deal directly only with in-plant problems. The
Department of Health has the legislative responsibility for dealing with solid and gaseous
environmental pollutants such as those arising from tanning processes, while the various
Regional Water Boards have authority over liquid waste discharge.

 Generation of Hydrogen Sulphide in Effluent Streams
A major hazard which could arise from improperly handled tanning effluent is the generation of
highly toxic hydrogen sulphide gas. If acidic liquid effluent is not neutralised before being
admitted into the general effluent sewer then its reaction with added sulphide solutions will
generate hydrogen sulphide Effluent treatment and disposal systems must be designed so as to
ensure neutralisation of acids before disposal to the general sewer

Annex 3:

Cleaner Production (CP) issues through Tanning Process
Cleaner Production Issues to Consider:

 Process fresh hides or skins to reduce the quantity of salt in wastewater, where feasible.

 Reduce the quantities of salt used for preservation. When salted skins are used as raw
material, preterit the skins with salt elimination methods.

 Use salt or chilling methods to preserve hides, instead of persistent insecticides and
fungicides.

 When antiseptics or biocides are necessary, avoid toxic and less degradable ones,
especially those containing arsenic, mercury, lindane, or pentachlorophenol or other
chlorinated substances.

 Flesh green hides instead of limed hides.

 Use sulphide and lime as a 20–50% solution to reduce sulphide levels in wastewater.

 Split limed hides to reduce the amount of chrome needed for tanning.

 Consider the use of carbon dioxide in deliming to reduce ammonia in wastewater.

 Use only trivalent chrome when required for tanning.

 Inject tanning solution in the skin using high-pressure nozzles; recover chrome from
chrome-containing wastewaters, which should be kept segregated from other wastewaters.

 Recycle chrome after precipitation and acidification. Improve fixation of chrome by addition
of dicarboxylic acids.

 Recycle spent chrome liquor to the tanning process or to the pickling vat.

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 Examine alternatives to chrome in tanning, such as titanium, aluminium, iron, zirconium,

and vegetable tanning agents.

 Use nonorganic solvents for dyeing and finishing.

 Recover hair by using hair-saving methods to reduce pollution loads. For example, avoid
dissolving hair in chemicals by making a proper choice of chemicals and using screens to
remove hair from wastewater.

 Use photocell-assisted paint-spraying techniques to avoid over-spraying.

 Precondition hides before vegetable tanning. Through good management, water use can
be reduced by 30–50%, to 25 litres per kilograms (l/kg) of raw material. Recommendations
for reducing water consumption include the following:

 Monitor and control process waters; reductions of up to 50% can be achieved.

 Use batch washing instead of continuous washing, for reductions of up to 50%.

 Use low-float methods (for example, use 40–80% floats). Recycle liming, pickling, and
tanning floats. Recycle sulphide in spent liming liquor after screening to reduce sulphide
losses (by, say, 20–50%) and lime loss (by about 40–60%).

 Use drums instead of pits for immersion of hides.

 Reuse wastewaters for washing—for example, by recycling lime wash water to the soaking
stage. Reuse treated wastewaters in the process to the extent feasible (for example, in
soaking and pickling).

Waste reduction measures should include the following:

 Recover hide trimmings for use in the manufacture of glue, gelatin, and similar products.
 Recover grease for rendering. Use aqueous degreasing methods.
 Recycle wastes to the extent feasible in the manufacture of fertilizer, animal feed, and

tallow, provided the quality of these products is not compromised.
 Use tanned shavings in leather board manufacture.
 Control odour problems by good housekeeping methods such as minimal storage of flesh

trimmings and organic material.
 Recover energy from the drying process to heat process water

Annex 4: Tanning Sector (case study on tannery CP ELICO Awash Tannery November 12, 2002

1) Reduction of painting Chemical Consumption

Problem- High chemical consumption
»168g/lit Na2S
»52g/lit NaHS
- High BOD level.
- Low efficiency of sulphide oxidation in effluent treatment plant.
Action Taken
- Concentration of chemical reduced.
» Na2S from 168g/lit to 135g/lit.
» NaHS from 52g /lit to 40g/lit.
Result of the Change
No change in quality
clean sheepskins, no fine hair & no rough skin

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Process 1.8 sheepskins (year).

Previous Current annual
consumption kg/annum

difference
in kg/annum

Na2S 100,800 81,000 19,800
NaHS 31,200 24,000 7,200
Total 132,000 105,000 27,000


Financial Benefit

Total saving of Birr 201,423.96 Birr, as
Na2S- Birr 143,324.28
NaHS- Birr 58,099.68

Environmental Benefit

- The discharge load has reduced by 27 ton per annum, in terms of total suspended solids (TSS) and
alkalinity reduced the volume of water to the effluent treatment plant. More over the new revised process
has shown marked improvement with respect to quality

2) Reduction of Lime Consumption in Hide Liming Process

Problem: - Drawn grain problem.
- Excess chemical consumption as

Undissolved lime in the drum.
- Long processing time.

Action Taken
Soaking time for dry hide reduced from 48 hours to 24 hrs.

Has been reduced.

From 7% to 4% for dry hide.
From 3% to 2% for wet salted hide.

From 2.75% to 2% for fresh hide.

Result of the change:

Several tests and assessment on quality show much better result on drawn grain, loose grain & flatness.
Touch of the pelt after soaking,
Splitting was much better

Total soaked weight in
kg/annum,

Previously consumed
lime kg/annum

currently consumed
lime kg/annum

Dry hide 888,052 62164.0 35522.1
Wet salted 69,279 2078.4 1385.6
Fresh hide 381,684 10,495.3 7633.7
Total lime
powder
consumption

74,495.3 44541.4

Financial Benefit
- birr 16,668.90 was saved
- Unquantified production reduction due to

Productivity improvement
quality improvement
reduced effluent treatment cost.

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Environmental Benefit
Reduced the environmental load of lime by 30 ton per annum, in terms of
total suspended solid (TSS)
Alkalinity

3) Chrome Recovery & Reuse

Recovered Chrome in lit/
month

%Cr2O3 Amount of 21 % Cr2O3
(kg/month)

1920 12.14 1109.9
2000 7.3 695.2
2000 7.0 666.7
Total in quarter 2471.8

Financial Benefit
Annual saving Birr 61,392 per annum
Environmental Benefit
Reduced chrome load to the environment by 9887 kg per annum.

Financial Benefit

Remedial Step Taken Savings
- reducing the size of the
boiler
- feeding water tank and
heating it.

409.40
Birr/day

- recovering condensate up
to 700c 32

20.02

- installing more direct
steam lines

Birr/day

considering 330 working day & 16 hrs a day annual saving:- Birr
162,241.20

4. Collection and Reuse of Painting Spillage

Observation:-
Painting solution
Spillage drained to the waste stream

Measurement:-
Spillage 16 to 17% of the supplied solution.

The estimated loss of chemical for annual production of 1 million pieces of skins
Annual Loss in kg Annual Loss in Birr

Na2S (kg) 5136 40060
NaHS 3424 24650
Lime 17200 10660
Total 15760 75370

For complete collection spillage, minimum requirement
Insolate the drainage line for painting solution
collecting tank

Action Taken
- Intermediate spillage collecting tank (before the drainage line)
- pallet arrangement … to reduce water contamination on the floor

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Data was colleted for months show, the following saving.

chemical Na2S(kg) NaHS Lime Total
Saving in kg 194.4 73.3 307.3 575
Saving in Birr 1552.20 527.80 190.50 2270.5

Financial Benefit:-
Birr 18340 per annum
Environmental Benefit:- Environmental load due to the Na2S, NaHS and Lime by
»575 kg in three month or
»4611 kg in a year.

Annex 5: Tannery Effluent Standard

Table 1.1 Emission Limit Values for Discharges to Water

Constituent Group or Parameter Emission Limit Value (mg/l)
Temperature 40 C
pH 6 – 9 pH units
BOD5 at 20C >90% Removal or 200 mg/l
COD 500
Suspended Solids 50
Total Ammonia (as N) 30
Total Nitrogen (as N) >80% Removal or 60 mg/l
Total Phosphorus (as P) >80% Removal or 10 mg/l
Oils, Fats, and Grease 15
Mineral Oil (Interceptor) 20
Chromium (as total Cr) 2
Chromium (as Cr VI) 0.1
Chloride (as Cl) 1000
Sulphide (as S) 1
Phenols 1

TABLE 1.2 EMISSION LIMIT VALUES FOR EMISSIONS TO AIR

Substance Concentration Limit (mg/Nm3)
Total Particulates 50
VOCs (degreasing) 50
VOCs (finishing) 75 g/m2 product produced
Total hydrogen sulphide, sulphides and mercaptans
(as S)

5 ppm v/v

Ammonia 40 ppm v/v
Acid vapours (as HCl) 30

Properly implemented CP:


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Annex 6: Best Available techniques (BAT) for the substitution of chemicals

Substances to be substituted are listed in the left column. BAT substitutes are listed in the right column.

SUBSTANCE BAT SUBSTITUTE
Biocides  Products with the lowest environmental and toxicological

impact, used at the lowest level possible e.g. sodium-or
potassium-di-methyl-thiocarbamate

Halogenated organic
compounds

 They can be substituted completely in almost every
case. This includes substitution for soaking, degreasing,
fat liquoring, dyeing agents and special post-tanning
agents
- Exception: the cleaning of Merino sheepskins

Organic solvents (non-
halogenated)

The finishing process and the
degreasing of sheepskins are the
major areas of relevance

Finishing:
 Aqueous-based finishing systems

- Exception: if very high standards of topcoat resistance
to wet-rubbing, wet-flexing and perspiration are required

 Low-organic solvent-based finishing systems
 Low aromatic contents
Sheepskin degreasing:
 The use of one organic solvent and not mixtures, to

facilitate possible re-use after distillation
Surfactants
APEs such as NPEs

 e.g. alcohol ethoxylates, where possible

Cmplexing agents
EDTA and NTA

 EDDS and MGDA, where possible

Ammonium deliming agents  Partially with carbon dioxide and/or weak organic acids
Tanning agents
- Chromium

- Syntans and resins

 20-35% of the fresh chrome input can be substituted by
recovered chrome

 Products with low formaldehyde, low phenol and low
acrylic acid monomer content

Dyestuffs  De-dusted or liquid dyestuffs
 High-exhausting dyes containing low amounts of salt
 Substitution of ammonia by auxilaries such as dye

penetrators
 Substitution of halogenic dyes by vinyl sulphone reactive

dyes

Fatliquoring agents  Free of agents building up AOX-
- Exception: waterproof leathers
 Applied in organic solvent-free mixtures or, when not

possible, low organic solvent mixtures
 High-exhausting to reduce the COD as much as possible

Finishing agents for topcoats,
binders (resins) and cross-linking
agents

 Binders based on polymeric emulsions with low
monomer content

 Cadmium-and lead-free pigments and finishing systems
Others:
- Water repellent agents

-Brominated and antimony-

 Free of agents building up AOX
- Exception: waterproof leathers
 Applied in organic solvent-free mixtures or, when not

possible, low organic solvent mixtures
 Free of metal salts
- Exception: waterproof leathers
 Phosphate-based flame retardants

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containing flame retardant

Annex 7. Process: Integrated BAT measures

PROCESS UNITPROCESS UNIT BAT is:BAT is:

B
E

A
M

H
O

U
S

E

Curing and soaking  To process fresh hides as far as they are available
Exceptions:

- When long transport time is necessary (max 8-12 hours for
fresh, unchilled hiders; 5-8 days if a cooling chain of 2oC is
maintained)
- For certain types of end-products
- Sheepskins, calf skins
 To reduce the amount of salt used as far as possible

Unhearing & liming  To use hair-save technology, but economics can be an issue
for existing plants when re-use of the saved hair is not
possible

 To reduce sulphide consumption by the use of enzyme
preparations; not for sheepskins

 To recycle spent liquors only when processing sheepskins,
which are dewoolled by painting

Splitting  To use lime splitting
Exceptions:

- When the starting material is wet blue
- When a firmer leather has to be produced (e.g shoe-
leather)
- When a more uniform and accurate thickness is needed in
the final product

 To maximise the use of split

T
A

N
Y

A
A

R
D

O
P

E
R

A
T

IO
N

S

Deliming and bating  To make a partial substitution of ammonium salts with CO2
and/or weak organic acids

Sheepskin
Degreasing

 To optimise wet degreasing using surfactabts, with or without
organic solvents

 Closed machines with abatement for air and waste water
releases when organic solvents are used to degrease skins
in dry state

Pickling  To use partial recycling or re-use of pickle liquors (*) split
view; see below

 To use a volume of floats in the range of 50 – 60% (based on
fleshed weight) for ovine skins and bovine hides in order to
reduce salt consumption

Tanning  To increase the efficiency of the chrome tanning process
through careful control of PH, float, temperature, time and
drum speed,

 To use chrome recovery through precipitation
Exceptions

- When specialised recovery plants are not available
-When the recovered chrome cannot be recycled in order
to produce high quality leathers.

 To use high –exhaustion tanning methods where chrome
recovery is not possible (exception;-high quality leather
production).

 To maximise exhaustion of vegetable tanning liquor with
counter-current (pit system ) or recycling (drum tanning)

EIA GUIDELIES FOR TANNERIES, April 2005 35


The EFDRE Environmental Protection Authority

P
O

S
T

-T
A

N
N

IN
G

O
P

E
R

A
T

IO
N

S

Retaining, chrome
fixation and
neutralization

 To enhance exhaustion of post-tanning treatment agents and
fixation of tanning agents in the leather

 To reduce the salt content of spent liquors
Dyeing  To enhance exhaustion of dyestuffs
Fat liquoring  To enhance exhaustion of fat liquor
Drying  To optimize mechanical dewatering prior to drying where

possible
Applying a surface
coat

 To use roller coating
 To use curtain coating
 To use HVLP spray guns
 To use airless spray guns

Exception for all four above-mentioned techniques:
- When very thin finishes are applied, e.g. on aniline and aniline-type
leather

Annex 8: BAT for water management and treatment

Within these areas, BAT is:

G
O

O
D


H

O
U

S
E

K
E

E
P

IN
G


A

N
D

P
R

O
C

E
S

S
IN

T
E

G
R

A
T

E
D

M
E

A
S

U
R

E

To improve the matching of water flow to the requirements of the process
To use ‘batch’ versus ‘running water’ washes
To modify existing equipment to use short floats
To use modern equipment for short floats
To re-use waste water in less critical processes
To recycle or re-use process liquors where possible

E
F

F
L

U
E

N
T

T
R

E
A

T
M

E
N

T

To keep sulphide-containing effluent from the beam house separate and at
high pH until the sulphide is removed. The associated emission level after
treatment is 2 mg S2- /1 in a random sample in the separate effluent. After the
sulphide is removed (on site or in a jointly used dedicated treatment plant) the
effluent can be mixed.

To collect chromium-containing partial effluent (e.g. from tanning and
samming) with a concentration of Crtotal>1 g/1 separately and send it for
chrome recovery. Chrome recovery can be done on or off site.
To use mechanical treatment (on or off site)
To use biological treatment (on or off site)
To use post-purification sedimentation and sludge handling (on or off site)

EIA GUIDELIES FOR TANNERIES, April 2005 36


The EFDRE Environmental Protection Authority

Annex 9: BAT for waste management

Re-use/recycling/recovery
and treatment

Type of waste

Leather production Splits
Leather fibre board
production

Tanned wastes in general, e.g., splits, shavings, trimmings

Small leather goods etc. Splits and tanned trimmings
Filling material, wool Hair and wool
Gelatine and/or hide glue Raw trimmings, green and limed fleshings and splits
Sausage casings Untanned splits
Fat recovery Raw trimmings, green and limed fleshings
Protein hydrolysate Hair, raw and limed trimmings, green and limed fleshings,

green limed and tanned splits and shavings
Collgen Limed trimmings and splits
Agriculture and fertilizer Hair for the nitrogen content, residues from composting and

anaerobic digestion, sludges from waste water treatment. The
legal requirements for the application of waste to land require
sophisticated waste separation and treatment of the various
fractions.

Compostion Hair, green and limed fleshings, green, limed and tanned
splits and shavings, fats grease and oil: sludges from waste
water treatment

Anaerobic digestion Hair, raw trimmings, green and limed fleshings, green, limed
splits, fats, grease and oil; sludges from waste water
treatment

Thermal treatment Fats, grease, mixtures of non-halogenated organic solvents
and oil

Recycling of organic solvents Organic solvents (no mixtures)
Regeneration of air
abatement filters

Activated carbon filters

Re-use and recycling of
packaging material by
feeding it back to the
supplier via an appropriate
recycling system

Container, pallets, plastic, cardboard

Annex 10

 General requirements

The organization shall establish and maintain an environmental management system, the
requirements of which are described below;-

o Environmental policy

 Top management shall define the organization‘s environmental policy

o Planning

EIA GUIDELIES FOR TANNERIES, April 2005 37


The EFDRE Environmental Protection Authority
 Environmental aspect

The organization shall establish and maintain (a) procedures to define the environmental
aspects of its activity, products or services that it can control over which it can expect to
have an influence, in order to determine those which have or can have significant impacts
on the environment

 Legal and other requirements

The organization shall establish and maintain a procedure to identify and have access to
legal and other requirements to which the organization subscribe, that applicable to the
environmental aspects of its activities , products or services.

 Objectives and targets

The organization shall establish and maintain documented environmental objectives and
targets, at each relevant faction and level within the organization.

 Environmental management programme(s)

The organization shall establish and maintain (a) programme(s) for achieving the
objectives and targets.

o Implementation and operation

 Stricture and responsibility

Roles, responsibility and authorities shall be defined documented
communicated in order to facilitate effective environmental management.

 Training, awareness and competence.

The organization shall identify training needs. It shall require that all
personnel whose work may crate a significant impact upon the
environment, have received appropriate training.

 Communication

With regard to its environmental aspects and the environmental management
system, the organization shall establish and maintain procedure for

a) International communication between the various
levels and functions of the organizations

b) Receiving the documenting and responding to relevant
communication from external interested parties

 Environmental management system documentation

The origination shall establish and maintain information, in paper or electronic
form to :
EIA GUIDELIES FOR TANNERIES, April 2005 38


The EFDRE Environmental Protection Authority
a) describe the core elements of the

management system and their reaction:
b) provide direction to related documentation

o Checking and corrective action

 Monitoring and measurement

The organization shall establish and maintain documented procedures to
monitor and measure, on a regular basis the key characteristics of its
operations and activities that can have a significant impact on the
environment.

 None conformance and corrective and protective action
The organization shall establish and maintain procedures for defining

responsibility and authority for handling and investigating non-conformance,
taking action to mitigate any impacts caused and for initiating and
completing corrective and prevention action.

 Records
The organization shall establish and maintain procedures and for the
identification, maintenance and disposition of environmental records.

 Environmental management system audit:-
The organization shall establish and maintain (a) programme (s) and
procedures for periodic environmental management system audits to be
carried out, in order to

a) Determine weather or not the environmental
Management system

b) Provide information on the results of audits to
managements


 Management review

The organization’s top management shall, at intervals that is determine, review
the environmental management system, to ensure its continuing suitability,
adequacy and effectiveness

EIA GUIDELIES FOR TANNERIES, April 2005 39


The EFDRE Environmental Protection Authority

EIA GUIDELIES FOR TANNERIES, April 2005 40


The EFDRE Environmental Protection Authority

Annex 11: Checklist for assessing Environmental Impact

 Water pollution from uncontrolled storm derange
 Water pollution from effluent and waste waters
 Water pollution from spills and accidents
 Groundwater pollution from ponds ,pits,, lagoons, holding thanks.
 Ground water pollution from waste dumps
 Impact on sewage treatment systems
 Impact on sewers and drains
 Soil pollution from effluent and waste water.
 Soil pollution from sledges and residues
 Contamination of land from spills
 Odors and nuisance toxic from decomposing wastes and chemical
 Toxic gas emission from chemicals , wastes and effluents
 Industrial hazard form chemicals, contact, fumes
 Hazards from treated hides (handling, effluent)
 Public hazards of waste dumps-chemicals , wastes, containers
 Noise , smoke, dust
 Water consumption
 Storage safety of chemicals
 Energy consumption
 Transport of chemicals, wastes and general materials
 Use of land which ecologically valuable

Annex 12: Environmental Criteria for locating the project in any area of the country

The following Environmental criteria for locating tanning industry project in any area of the country should
be given due consideration.

 Environmental Sensitivity value and availability based on the uniqueness, sensitivity and inventory
of natural resources in the specific section of the identified areas;

 Importance social importance and priority based on heritage and archaeological sites and level of
attractiveness to the public for purposes of leisure, tourism and recreation;

 Land use zone whether the selected area is in compatible with the national or local land use plans
or not;

 Alternative technologies Introduction and promotion of environmental sound alternative
technologies, which are suitable to the local situation;

 Carrying capacity of the natural resources; etc.

EIA GUIDELIES FOR TANNERIES, April 2005 41


The EFDRE Environmental Protection Authority

References

1. UNIDO /EPA proceeding of consultation and awareness workshop on the industrial
effluent / emission limits for Ethiopia 17-18 April 2003

2. Provisional standard for industrial pollution control in Ethiopia April 2003 Addis Abab
3. Assessment report for the preparation of standards for industrial pollution control in

Ethiopia April 2003 Addis Ababa
4. Federal Democratic Republic of Ethiopia industrial environmental policy and strategy

Addis Ababa( 4-7 December 2001)
5. UNEP/UNDO Tanneries and environment a technical guide
6. ECPC workshop on cleaner production in tanning industries Dec.12/2002
7. Proclamation No, 1/1995 of the Constitution of the Federal Democratic republic of

Ethiopia
8. Papers presented on technical workshop on good practices for the Ethiopian hides and

skin industry 4-7 December 2001 Addis Ababa
9. Ethiopian Environmental Protection Agency Environmental Auditor training course by

aspects international Ltd.
10. Ethiopian leather journal Vol.1 Oct-Dec. 2004
11. Health policy of the transitional government of Ethiopia sep,1993
12. Ministry of water resources ,Ethiopian water resources management policy
13. Seminar on tannery pollution control and effluent treatment on Occupational safety and

health aspects of leather manufacture by Netseha Sequar March 29-31
14. Public health proclamation No 200/2000 March 29-31
15. Environmental policy of Ethiopia April 2,1997
16. Aspects International Ltd environmental auditor training course 2002
17. OSH department of labour chemical handling in the chemical industry reformatted 2004
18. EU Integrated pollution prevention and control (IPPC reference document on best

available techniques for the tanning of hides and skins may 2001
19. FEPA BAT Best Available Techniques for the Fellmongering and Tanning Industry

EIA GUIDELIES FOR TANNERIES, April 2005 42


The EFDRE Environmental Protection Authority

Table of Contents

Acronyms ................................ .................... .................... ........................................................................................................................................1

Glossary........................................................ .................... ...................................................................................................................
.....................2

1 Introduction and Background...........................................................................................................................................................................6

2 Legal, Institutional and policy Frameworks................................................................................................................................................7

2.1 Legal frame work..................................................................................................................................................................................7
2.1.1 The Constitution of the Federal Democratic Republic of Ethiopia..............................................................................................7
2.1.2 Environmental proclamations.......................................................................................................................................................7

2.2 Institutional framework........................................................................................................................................................................8

2.3 Frame Work Policies............................................................................................................................................................................8

3 Tanning Process..............................................................................................................................................................................................9

3.1 What is Tanning?..................................................................................................................................................................................9

3.2 Major operations..................................................................................................................................................................................9
3.2.1 Hide and skin storage and beam house operations.......................................................................................................................9
3.2.2 Tan yard process.........................................................................................................................................................................10
3.2.3 Post-tanning Wet Work...............................................................................................................................................................10
3.2.4 Drying and Finishing..................................................................................................................................................................10

3.3 Impacts of Tanning Industry on the Environment..............................................................................................................................13
3.3.1 Impact on Air, Water and Land..................................................................................................................................................13
3.3.2 Impact on human health and occupational safety due to exposure to hazardous chemical........................................................14

 Hazards related to tannery workers...........................................................................................................................................................14

4 THE NEED FOR POLLUTION CONTROL............................................................................................................................................20

4.1 Basic waste management hierarchy...................................................................................................................................................20

ANNEXES.................................................................................................................................................................................................................26

Annex 1 .......................................................................................................................................................................................27

Annex 2 .......................................................................................................................................................................................28

Annex 3: Tanning Sector (case study on tannery CP ELICO Awash Tannery November 12, 2002.........................................29

Annex 4: Tannery Effluent Standard..............................................................................................................................................32

Annex 5: Best Available techniques (BAT) for the substitution of chemicals..............................................................................33

Annex 6. Process: Integrated BAT measures..................................................................................................................................34

Annex 7: BAT for water management and treatment...................................................................................................................35

Annex 8: BAT for waste management............................................................................................................................................36

Annex 9: Checklist for assessing Environmental Impact.............................................................................................................40

Annex 10: Environmental Criteria for locating the project in any area of the country............................................................40

References..................................................................................................................................................................................................................41


EIA GUIDELIES FOR TANNERIES, April 2005 43


1 Introduction and Background
2 Legal, Institutional and policy Frameworks
2.1 Legal frame work
2.1.1 The Constitution of the Federal Democratic Republic of Ethiopia
2.1.2 Environmental proclamations

2.2 Institutional framework
2.3 Frame Work Policies

3 Tanning Process
3.1 What is Tanning?
3.2 Major operations
3.2.1 Hide and skin storage and beam house operations
3.2.2 Tan yard process
3.2.3 Post-tanning Wet Work
3.2.4 Drying and Finishing

3.3 Impacts of Tanning Industry on the Environment
3.3.1 Impact on Air, Water and Land
3.3.2 Impact on human health and occupational safety due to exposure to hazardous chemical


4 Hazards related to tannery workers
Labelling procedure
Store chemical safely
Storage requirements
Health and Safety Measures
Disposal

5 THE NEED FOR POLLUTION CONTROL
5.1 Basic waste management hierarchy

6 Treatment
GENERAL PRINCIPLES
6.1 ALTERNATIVE TECHNIQUES
Best Available Techniques
Environmental audit


ANNEXES
Annex 1
Annex 2
Annex 3:
Cleaner Production (CP) issues through Tanning Process

Annex 4: Tanning Sector (case study on tannery CP ELICO Awash Tannery November 12, 2002
Annex 5: Tannery Effluent Standard
Annex 6: Best Available techniques (BAT) for the substitution of chemicals
Annex 7. Process: Integrated BAT measures
Annex 8: BAT for water management and treatment
Annex 9: BAT for waste management
Annex 11: Checklist for assessing Environmental Impact
Annex 12: Environmental Criteria for locating the project in any area of the country
References


N

Ly
ez

Oxidizing Harmful Irritant Dangerous to
highly flammable Toxic Corrosive the Environment


POLLUTION PREVENTION HIERARCHY
as established by Congress in the
Pollution Prevention Act of 1990

Prevention and Reduction
Recycling and Reuse,


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— Hair Peoovery
Process

reyes
Assisted Dehaiing | @F Sulphide

Ammonia © ee To annonia

in Effluent “A sats DELINING Pairing Pin Effluent
—s

PETE Reduced

Chromiun > Updscteshauston fe Erivont
ec


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in Effluent