The only true leather-building substance in raw hide is corium collagen, everything else (hair, epidermis, fat, some proteinaceous matter etc.) has to be removed for which purpose substantial quantities of both general and specialty chemicals are needed; only some 20 % of them is actually retained by leather. Agglomerations of traditional tanning units with inadequate investment potential, lack of space and specific skills were conducive for setting up Common Effluent Treatment Plants (CETPs) servicing tannery clusters, the concept also adopted in relocations and/or establishing new leather clusters in developing countries. Due to only gradual increase in volumes of effluents and seasonal fluctuations associated with religious festivals, new CETPs are designed in modular way. On-site, physical-chemical (primary) treatment, including strict segregation of streams, catalytic oxidation of sulphide bearing spent floats, chrome management as well as equalization, settling, sludge removal and dewatering are by now already well-established technologies; the biological (secondary) treatment, typically using activated sludge method, often in raceways, in addition to high energy consumption, requires experienced personnel and close monitoring, in particular the removal of excess nitrogen (nitrification/denitrification). 

However, reutilisation and/or safe disposal of sludges remains a challenge to deal with. It appears that in very arid regions the best option to overcome the problem of Total Dissolve Solids (TDS, colloquially salinity) is to link tannery (C)ETPs with Municipal Wastewater Works (MWW).

Furthermore, it is important for the leather sector to take a proactive role in battling negative publicity and spreading of misleading information by fake green lobbies and pressure groups. Better coordination among various national, regional and global leather organizations, including R & D institutions would make a stronger impact.

Tanning industry is an important segment of UNIDO technical assistance in promoting sustainable development. In late 90-ies a number of studies dealing with various cleaner tanning methods, including the widely used paper The Scope for decreasing pollution load in leather processing, were prepared to support different forms of training activities (shop-floor demonstrations, pilot plants, national and regional workshops etc).

In the meantime a lot of practical experience has been gathered, some new tanning technologies developed and implemented and some new challenges have also emerged.  Since proper training is essential precondition for modern, sustainable leather processing, it is felt that a single, comprehensive paper on cleaner leather technologies, rounding up and updating earlier papers, could be of great help in training and capacity building activities.

In addition to traditional cleaner technologies topics such as pollution sources/loads, water management, hair-save liming, low- or ammonia-free deliming, chrome management, low-organic solvents finishing, solid waste management etc., this comprehensive study addresses virtually all issues relevant for performance and successful tanning operations: tannery environmental management systems (EMS/CSR), Restricted Substances Lists (RSL), energy considerations, mechanical operations, Occupational Safety and Health at workplace (OSH), Carbon Footprint (CF) and Life Cycle Analysis (LCA) which are so often the subject of extensive debates in various international fora and media.

The study also includes many tables, charts and (equipment) photos accompanying and illustrating the text.

It is envisaged that the document will serve as a basis for developing globally accessible eLearning courses on sustainable leather manufacture.

There are also other useful information and sources e.g. Tannery of the Future. The Tannery of the Future tool gives tanners an initial indication of the areas in which they need to become more sustainable, e.g. housekeeping, waste management, working conditions and wages. It also provides references to sources of more in-depth information and guidance.

The Leather Working Group (LWG) has launched an online training platform designed to educate leather manufacturers and other members of the leather supply chain on responsible operating practices.

The study titled Life Cycle Assessment, Carbon Footprint in Leather Processing prepared for and presented by F. Brugnoli during the XVIII Session of UNIDO Leather and Leather Products Industry Panel in Shanghai in 2012 provided detailed explanations, definitions and terminology pertaining to leather’s carbon footprint.

It also contained specific suggestions on how to proceed in addressing this issue. Subsequently, it was not only extensively discussed by eminent international leather specialists, but it has triggered a series of activities involving different regional and global establishments.

The essence of that paper, reactions to it and some other views were reflected in a special chapter in UNIDO’s comprehensive study The Framework for Sustainable Leather  Manufacture, a chapter dealing with carbon footprint aspects of leather processing.

That chapter is now here presented as separate paper for the benefit of readers primarily interested in the carbon footprint considerations. 

In addition to earlier content, the paper also presents the main features of the European Standard EN 16887 (approved in Nov 2016, published in March 2017, applicable not later than Sept 2017) Leather – Environmental footprint – Product Category Rules (PCR) – Carbon footprints. It is quite likely that the European norm will prevail globally.

Historically, for various reasons, tanneries have been generally found in clusters in many countries. In several countries that still possess a strong tanning industry, the industry has either been able to deal collectively with the environmental challenges by means of common waste treatment facilities in existing clusters (e.g. India, Italy, Pakistan) or is in the process of relocation.

Within almost all projects of tannery relocation there are common reasons and the main problems faced by the industry at the current location are:

With no infrastructure for treatment of solid or liquid waste generated by tanneries, a very unhygienic atmosphere has been created in the entire locality due to discharge/disposal of untreated solid and liquid wastes.

Due to extreme limitations of space, even tanneries wanting to modernize and become more efficient in terms of production and environment management are unable to do so. The present location, in this manner, has become a serious constraint for the growth of the industry.

Downstream industries such as footwear, leather garment and leather goods, depend on the tanning industry for supply of quality leather. The existing limitations have put a limit to the growth of leather products industries.

Relocation of the tanneries to a more spacious location with appropriate infrastructure for efficient and cost effective treatment of solid and liquid wastes has thus become a prerequisite for survival and growth of the leather industry in such cases.