How to Conduct EIA for Leather Processing Industry

calendar21 Mar, 2023
timeReading Time: 5 Minutes
How to Conduct EIA for Leather Processing Industry

EIA, after its introduction in 1994, has worked to ensure sustained development in the country. The existing version of the EIA process was issued on September 14, 2006, that brought out structural changes in the Environment clearance mechanism for 39 identified industries, including the leather /skin/hide processing industry. Leather processing includes stages associated with consuming large amounts of water and generating solid and liquid wastes. Therefore, EIA for the Leather processing industry was introduced as a regulatory mechanism for this highly polluting yet crucial business. The wastewaters from the industry contain abundant inorganic and organic compounds such as chloride, ammonia, chromium, sulfide and sulfate. The process involves a sequence of complex chemical reactions and mechanical pre- and post-treatment processes. As the industry’s demand varies, so has the process that has evolved with time to include more and more processing activities to give specific characteristics to finished leather.

The most polluting part of leather processing is tanning. Pre-tanning and tanning contribute about 90% of the pollution caused by the leather industry. These steps are performed in facilities called tanneries, and the leather industry is heavily dependent on these. The most commonly used industrial tanning method is based on chromium, a heavy metal that in large amounts, can be dangerous to both humans and the environment. In this article, we will understand how the government has tried to balance development and environment conservation by mandating EIA for Leather processing industry.

Environment Impact and Waste Generation from the Leather Industry

The processing activity in the leather industry involves converting raw hide into leather and converting a highly putrescible material into a stable material. To prevent and reduce any potential impact that this industry may possess, the government felt a need for Environmental Impact Assessment (EIA) for Leather processing industry to regulate this industry.

  • Wastewater: In the course of processing hides into leather, roughly 50-150 litres of water is used to convert one kilogram of leather. Many times effluents are discharged indiscriminately without any pre-treatment into water bodies or open land, resulting in contamination of surface as well as sub-surface water.
  • Air Emissions: Tanneries release various gaseous pollutants such as ammonia, amines, aldehydes, hydrogen sulfide and volatile hydrocarbons into the atmosphere as effluents.
  • Solid Waste: Wastes from untanned skin/hides (e.g. trimmings and fleshing wastes), Wastes from tanned leather (e.g. shaving wastes and buffing dust) or wastes from dyed and finished leather (e.g. trimmings).

Relevance EIA for Leather Processing Industry

Effluents discharged from tanneries are voluminous, highly coloured, and contain a heavy sediment load, including toxic metallic compounds, chemicals, biologically oxidisable materials and large quantities of putrefying suspended matter. The following are the major environmental concerns associated with the leather Industry.

Aquatic Eco-Toxicity: Aquatic toxicity generally refers to a chemical’s effects on organisms living in water. Tanning can release different chemicals if done unregulated and lead to runoffs of these chemicals into waterbodies causing aquatic eco-toxicity for aquatic organisms.

Aquatic Acidification: Acidification refers to a reduction in the pH levels of waterbody over a period of time caused by the uptake of carbon dioxide (CO2) from the atmosphere. The pre-tanning operation can cause differences in pH levels by the wastewater in the water bodies, thereby increasing the chemical oxygen demand (COD, chlorides), total dissolved solids (TDS) and sulfate.

Aquatic Eutrophication: When an entire waterbody, or parts of it, becomes enriched with minerals and nutrients, particularly nitrogen and phosphorus and shows increased phytoplankton production, it is known as aquatic eutrophication. The bacterial degradation of the excess biomass, therefore, results in increased oxygen consumption, creating hypoxia for other marine organisms.

High Use of Chemicals (Carcinogens and Non- Carcinogens): Converting hides into leather is a chemical-intensive process that utilises roughly 130 chemicals. The chemicals used in the various processing stages include

  • Sodium sulfide
  • Lime powder
  • Ammonium sulfate
  • Sodium chloride
  • Sulfuric acid
  • Chromium sulfate
  • Sulphonated and sulfated oils
  • Formaldehyde
  • Pigments
  • Dyes and
  • Anti-fungus agents

These concerns have made EIA for Leather processing industry a must to curb environmental pollution, especially in the case of water pollution.

Stages of EIA in Case of Tanneries


In the path towards EIA for Leather processing industry, any leather processing project falling under Category B will be treated as Category A if located within 10 km from the boundary of:

  • Protected areas notified under the Wild Life (Protection) Act,1972[1]
  • Critically polluted areas, as notified by the CPCB from time to time
  • Eco-sensitive areas, as notified under Section 3 of the E(P) Act, 1986, and
  • Inter-State boundaries and international boundaries

Note:  If any of the conditions listed in the above general condition applies, then a Category B project will be treated as Category A during the process of EIA for Leather processing industry.

Site Selection

Sites located near water resources such as lakes, rivers, ponds etc., used for drinking water bodies or agriculture use and or major groundwater resources used for public drinking water sources or sanctuaries or sensitive eco parks within 2 km will not be permitted to start tanneries in any category.

During EIA for Leather processing industry, siting care should be taken to minimise the impact of the processing industry on the immediate neighbourhood and distant places. To protect such sites, a leather processing industry may maintain the following distances,

Location Distance
Coastal Areas Preferably ½ km away from the high tide line.  
Flood Plain of the Riverine System Preferably ½ km away from flood plain or modified flood plain affected by a dam in the upstream or by flood control systems
Transport/Communication System Preferably ½ km away from highway and railway line
Major settlements (population above 3,00,000) industry shall be sited at least 10 km from the projected growth boundary of the settlement
Ecologically and/or otherwise sensitive areas Preferably 5 km


Scoping at the 2nd stage in the EIA for Leather processing industry. It is taken up soon after the project contours are defined. The primary purpose of scoping is to identify the concerns and issues which may affect the project decisions. Stages in Scoping include

Step 1: The project proponent must submit the application to the concerned authority. The application (Form 1 as given in Annexure II) shall be attached with the pre-feasibility report and proposed ToR for EIA studies. From pre-feasibility information and Form 1, valued environmental components (VECs) are identified for a given project.

Step 2: Once the project details from the pre-feasibility report & Form 1; and VECs are identified, a matrix establishing the interactions which can lead to any impacts is developed.

Step 3: Site Visit: The concerned EAC/SEAC may formulate a sub-committee for a site visit if considered necessary. EAC/SEAC will provide an opportunity to the project proponent for presentation and discussions on the proposed project and related issues, as well as the proposed ToR for EIA studies.

Step 5: The final set of ToR for EIA Studies is conveyed to the proponent by the EAC/ SEAC within sixty days of the receipt of Form 1 and the pre-feasibility report.

Term of Reference

At this stage, the project proponent/consultant must apply to the appraisal authority (SEIAA/SEAC) for Category B  projects or the MoEF&CC if the project falls in Category A. Terms of reference in case of EIA for Leather processing industry may include an executive summary of the project, giving an idea of the proposal’s objectives, use of resources, justification, etc. It should provide a brief compilation of the EIA report, including EMP and the post-project monitoring plan.

Preparation of Draft Environmental Impact Assessment Report

The draft report of an EIA includes the baseline details and impacts of the project and the development of mitigation measures accordingly.

Public Consultation

A public hearing will be conducted as per the provisions of the EIA Notification 2006, and the proposal of the unit will be presented to the public for their opinion and views on the existing or proposed project.


At this stage, the decision on whether the final EIA report prepared is satisfactory. The concerned authority (MoEF&CC/ SEIAA) will grant or reject the EC at this stage.


Conducting EIA for Leather processing industry requires expertise in administrative, project management, technical, scientific, social, economic, risk, etc., to analyse the issues of concern and draw logical interpretations. The processing of leather produce effluents that contain high biochemical oxygen demand (BOD), suspended solids (SS) such as grease and fibre, chemical oxygen demand (COD), and TDS (total dissolved solids). As the industry is categorised as one of the 17 most polluting sectors and placed in the red category of industry, tanneries/leather/skin/hide processing needs EIA prior to its setup. The assistance of certified EIA consultants can speed up the entire process and reduce the chances of rejection.

Also Read:
Industries And Sectors That Have EC Exemption

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