Enzymes have been used in the tanning industry for years because they are efficient at degrading protein and fat. In early times, the enzymes were derived from animal excrement, and later on from the pancreas of cattle. Today, many of the enzymes are produced using microbial fermentation, and Novozymes is a supplier of this type of enzyme.
Comparing enzymatic and chemical processes
One of the applications of microbial enzymes in the tanning industry is in soaking and unhairing processes. Novozymes has worked with a Chinese tannery to assess the environmental implications of applying enzymes in the soaking and unhairing of bovine hides.
By using the enzymes Greasex ® 50 L and NovoCor ® SG for soaking and to degrade fat and proteins, the Chinese tannery reduced soaking time leading to electricity savings in turning the drum.
Savings in chemicals
The unhairing enzyme Enzyme.htm">NUE 0.6 MPX was used to degrade proteins. It reduced the sulphide requirements for the process without influencing the processing time or temperature. The lower level of sulphides required reduces the sulphide content of the wastewater and some manganese sulphide can be saved.
The assessment shows that a small amount of enzyme products made from a biological production process replaces a relatively large amount of harsh chemicals made using a relatively large amount of energy derived mainly from coal.
Contributions to other environmental impacts such as acidification, nutrient enrichment and smog formation are also reduced. In fact, the environmental impacts resulting from enzyme production are at least 20 times lower than the impacts that are avoided by the savings in chemical and electricity consumption.
Global impact
The global supply of bovine heads for leather production was about 8.8 million tons in 2005. Today, less than 10% of bovine hides are soaked and unhaired in enzyme-assisted processes. Assuming that the environmental improvements observed in this study by switching from conventional to enzyme-assisted soaking and unhairing are applicable worldwide, the global potential saving is in order of 0.7 million tons of carbon dioxide per year. This is equivalent to the annual load from 75,000 average world citizens or 170,000 cars.