Sustainable water management in tanneries is #1 eco concern
On the 25th September 2015 the United Nations General Assembly ratified the Sustainable Development Goals (SDGs). These 17 goals contain issues that are all intertwined and working on achieving them is the task of a generation or even more. What is notable about the SDGs is that there is one directly linked to water and our human usage of this precious resource, underlining its importance. Something the leather industry has taken to heart for years in regards to sustainable water management.
SDG 6: Clean Water and Sanitation
Ensure availability and sustainable management of water and sanitation for all.
Global water use and leather
In the 2019 UNESCO World Water Assessment report, it’s estimated that global water demand will exceed supply by 20-30% by 2050. Compared to other estimates, that is a positive. Already 22 countries suffer serious water stress, which has a major impact on population, industry and the environment. Parts of Europe are already reaching water stress levels above acceptable norms and over 90% of natural disasters are water related. If anything, these numbers prove that change is not optional but necessary.
According to UNIDO research, water consumption per kilogram of hide is 12 to 37 liters of water. To give you an idea of comparison, for 1 kilogram of cotton around 10,000 liters are used1. It illustrates that to produce the materials we use, we need water. Of global water consumers, agriculture is the biggest user with over 69%, followed by industry (19%) and households (12%). Leather production accounts for a tiny percentage, something close to 0.02%, of total water consumption. A lot has already been done to change the impact of leather production, but still the industry will use (and recycle) water – it is one of their main resources.
Sustainable water management in tanneries
Sustainable water management is not a new focus point for the leather industry, and since the ratification of the SDGs, it’s only upped its game. Obviously, leather production can’t do without water, but we can manage the resources better and more efficiently, and also lower the impact of pollution. A number of things have already been done, many of them for several decades already:
- Switch from running water washing to batch washing – by using a closed drum (with a more efficient design), a continuous flow is no longer necessary. Since 30-50% of the water is used in this process, savings are significant. Smart design of the drums also removes the need for intense cleaning and make it easier to remove residues.
- Low float techniques – by reducing the amount of float (water) hides are soaked in and increasing chemical efficiency, water use can be significantly reduced. Finding the optimal method of chemical application is key, as chemical intensity can damage the hide.
- Recycle and reuse process water – smarter drums and water treatment technologies make it possible to remove effluent and reuse and recycle of water in processes. This is already being done in most of the developed world and many tanneries in developing nations, and can lead to vast savings. Build-up of chemicals and organic content can cause risk, but modern measuring enables tanners to optimize their processes and water treatment to minimize environmental risk. We explain more of this in [article 23] here.
It needs to be said that technical innovations, like hide processors, compartmental drums and computerized monitoring systems make a lot of these innovations possible and beneficial to the process. Good housekeeping (energy efficient dryers, clean floors, no leaky valves, fleshing collection) can make another significant difference in the resource efficiency of a modern tannery.
Reducing the water footprint
Data shows that in the last 25 years, water use in leather production has declined by about 37%. The average of 60m3 of water per ton of hides (1994) is now 38m3 ton per hide (2019) and in many tanneries even lower. The industry share in the global water footprint has, therefore, decreased as well. These results show that water management is vitally important for European tanners, but more important even is the way tanneries take care of their waste materials, which are contained in the downflow of production waters. Something they have already turned into an art.
We will look further at water resourcing in the next article.
- Buljan, J., Král, I. (2019) The framework for sustainable leather manufacture. UNIDO. Retrieved from: Leather Panel. [Accessed on 30 July 2020]
- Gutterres, M., Aquim, P, Passos, J. Trierweiler, J. (2010) Water reuse in tannery beamhouse process. Journal of cleaner production. Vol. 18, 1545-1552. Retrieved from: IHE Delft. [Accessed on 9 July 2020]
- Independent Group of Scientists appointed by the Secretary-General (2019) Global Sustainable Development Report 2019: The Future is Now – Science for Achieving Sustainable Development. United States, New York. Retrieved from: Sustainable Development. [Accessed on 8 July 2020]
- Nothing To Hide (2015) Essay Ten: Water Consumption – Reducing water use in tanneries. Retrieved from: Nothing To Hide. [Accessed on 8 July 2020]
- Sundar, V., Ramesh, R., Rao, PS, Saravanan, P., Sridharnath, B., Muralidharan, C. (2001) Water management in Leather Industry. Journal of Scientific & Industrial Research Vol. 30, June 2001. Retrieved from: JSIR. [Accessed on 9 July 2020]
- Swartz, C., Jackson-Moss, C., Rowswell, RA., Mpofu, AB, Welz, PJ. (2017) Water and Wastewater Management in the Tanning and Leather Finishing Industry: Natsurv 10 (2nd edition) – Report to the Water Research Commission. Retrieved from: Research Gate. [Accessed on 8 July 2020]
- WWAP (UNESCO World Water Assessment Programme). 2019. The United NationsWorld Water Development Report 2019: Leaving No One Behind. Paris, UNESCO. Retrieved from: UNESDOC. [Accessed on8 July 2020]
1One could argue that leather as a by-product is also responsible for agriculture use, which takes 20,000 liters of water to produce. For that reason a percentage of the animal rearing is allocated to leather (3.5%) according to the COTANCE Product Environmental Footprint Category Rules.