Since the introduction of industrial processing, tanneries have rarely innovated to adequately solve sustainability issues. A recent study by Juan-Carlos Castell of Proviera and Claus Reineking of Stahl found some natural probiotic alternatives that can replace traditional chemical methods.
Processing hides produces large amounts of waste water and solid residues, many of which are valuable for other applications if they are not contaminated by chemicals. For example, 1 ton of salted cowhide requires 500 kg of chemicals to produce half the weight of finished leather.
Therefore, tanners must manage a large excess of non-leather materials to avoid contamination. When applying R3 environmental strategies, the main potential actions are concentrated in several areas:
Biotechnology is now suitable to support tanners in implementing R3 environmental strategies by reducing the need for synthetic chemicals, improving consumption, and increasing the value of by-products. In addition, probiotic-based technology brings other sustainable benefits, such as natural fermentation processes, fully renewable raw materials, 100% biodegradable and safe biochemical products, reducing carbon footprint, and improving the quality of leather products.
The term "probiotics" has been commonly used for more than 25 years and the definition has been improved, but it is most commonly used to describe living microorganisms that have health benefits. It is at the forefront of developing technologies for a range of applications, including human health, agricultural and industrial waste management, and leather and textile processing.
Probiotics use beneficial and effective microorganisms to refill the environment of healthy microorganisms. The raw materials are carefully fermented with a mother culture of probiotic bacteria to produce metabolites composed of a biochemical mixture. The parent culture is the selection of microorganisms that grow in the "community", which combines the common growth process of multiple strains during the production process. Microbes become a small ecosystem, which is more resilient and able to work together. This is similar to how microorganisms live in nature. In nature, strains will never exist in isolation or as pure cultures.
Microbes are always interacting. When comparing innovative and destructive probiotic technology with traditional chemical synthesis, significant differences can be noticed:
Each microbial strain has specific characteristics and its metabolites, enabling them to provide degreasing, dispersion and conditioning functions. These properties are obtained through careful use of additives, which are processed using specific manufacturing systems.
Probiotic biochemical substances are hydrotropes, which have the ability to increase the solubility of organic molecules in water. The composition contains some hydrophilic and lipophilic properties, such as typical surfactants, but they contain very small hydrophobic parts and do not allow the formation of aggregates, such as micelles. In the first stage, the dirt, feces, wax, and phospholipids in soluble or unstructured proteins (such as hyaluronic acid, dermatan sulfate, elastin, glycosaminoglycans, and globulin) are broken down, dissolved and dispersed to float In leather processing, mainly soaking operation. Processing chemicals, such as tanning and retanning agents, fatliquors and dyes, are added in aqueous solutions to bind the functional groups of collagen used for tanning or to provide leather products with all physical properties during wet end operations.
In addition, when hydrotropes come into contact with collective structures (such as collagen fibers), they are considered to be excellent wetting agents. They allow the medium to accept water and work like a surfactant to break the surface tension of the fluid and help it transfer from one particle to another. Therefore, water molecules can penetrate the fibrous collagen structure into fibrils and microfibrils, break hydrogen bonds and activate protein functional groups. This wetting effect is related to slight lyotropic swelling and relaxes the fiber structure, thereby fixing ionic substances.
Probiotic biochemical products have a strong ability to eliminate or at least reduce and combine various soaking and wetting agents, enzymes, degreasing agents, dispersing agents, solvents, dye additives and ammonia, all of which are widely used in beam chambers and humidification. Department operations. Most of these reagents cause the emission of pollutants and are not completely biodegradable.
Because their role is to reduce surface tension, surfactants require additional washing to be removed from the leather. Probiotic biochemical products do not foam, so water consumption may be saved.
Probiotic biochemical products are compatible with all the chemicals used in the tanning process and do not need to be adjusted beyond the conditions (such as pH and temperature) required for manufacturing operations.
Except under unusual circumstances-such as insufficient preservation or prolonged soaking-soaking operations using probiotic biochemical agents do not contain fungicides, which can reduce odor or spoilage.
Although the need for fungicides in soaking depends on the sum of all prevailing conditions, they are habitually added to the tannery. Treatment of biocides requires adequate safety equipment to increase emissions costs, such as COD and the impact on the efficiency of wastewater treatment plants' bioreactors.
Probiotic biochemical products cannot be regarded as fungicides, but due to bacterial competitive exclusion or quorum sensing, they can delay the harmful effects of certain spoilage bacteria (such as Bacillus, E. coli, and Listeria) within a limited time.
This study summarizes a series of tests conducted on different materials in industrial barrels and pilot plants, from salted to fresh raw hides from different origins, as well as sheep, goat and wet blue skins. All demonstrations followed the same treatment protocol, and the dosage and conditions were adjusted as described.
Three different probiotic biochemical products (patent pending) have been designed to distinguish them by their hydrophile-lipophile balance (HLB). This is to obtain higher immersion, dispersion or degreasing performance. The product is named probiotic soaking agent (PK), probiotic dispersant (PS) and probiotic degreasing agent (PD).
The purpose is to remove dirt from animals (feces, blood, etc.) and preservatives (salt and biocide). In salted hides, additional washing is used to reduce the salt concentration and provide surface degreasing to remove external waxes and phospholipids on the hair and epidermis. Measured by green weight:
Probiotic biochemical products replace surfactants, enzymes (soaking agents) and degreasing agents. No biocides are added.
The purpose is to rehydrate the hides and skins and put them in a relaxed state for subsequent operations and to remove some globular proteins that would interfere with the tanning process. Measured by green weight:
The purpose is to remove the hair through the action of alkali and further complete the globular protein. Measured by green weight:
This eliminates or reduces the use of amines, organic reducing agents, and polyphosphates, all of which are typical additives in the dehairing and liming process.
The purpose is to peel the natural fat from the adipose tissue, especially the skin, disperse the natural fat in floats, and dissolve them through emulsification of surfactants or hydrolysis under the action of lipase. The test is carried out after deliming, before or during the softening of cowhide, goat and sheep skin, or after pickling/deacidification of sheep skin. In most cases, non-ionic surfactants with high emulsifying effect are used for post-washing. The dosage is based on the weight of lime fur:
Probiotics biochemistry can replace degreasing agents based on a mixture of surfactants and lipases, or at least significantly reduce degreasing agents and have a synergistic effect with them. They can eliminate the need for solvents because natural fats can be easily peeled off the fur.
The goal is to preserve and transform the hides into useful commodities and achieve resistance to bacterial attack and high temperatures. Typical tanning methods are mineral (mainly chromium), vegetable and organic (aldehydes and oils). Measured by the weight of lime fur:
This provides an alternative to dispersants and tanning aids.
The goal is to rehydrate tanned leather, wet blue leather, wet white leather or vegetable tanned leather after stacking or storage for a period of time; cleaning the leather to obtain a regular surface and obtain regular rehydration; chelation from mineral tanning Leached metal cations. Weight loss medication:
Probiotics can replace surfactants, ammonia and oxalic acid, and are often used to clean wet blue, wet white or vegetable leather.
The goal is to add and fix processing chemicals-such as retanning agents, fatliquors and dyes-to achieve the final characteristics of leather products. The dose is twice the weight of the shaving, or the weight of the shell (pearl):
This provides alternatives to surfactants, ammonia, and dyes derived from naphthalenesulfonic acid and ethoxylated amines.
Innovative all-natural probiotic biochemical products can replace traditional chemicals in leather tanning. Using a unique probiotic formula, biochemical products can improve leather quality, increase production, reduce operating costs and reduce environmental pollution.
Raw hides and hides are based on animal types (cattle, sheep, pigs, etc.) and different breeds, fat content (pre-removed meat from raw hides-mechanically removed fat, different animal types have different levels of natural fat and other characteristics), source (temperature is The biggest indicators of fat content: the colder the environment, the more fat), preservation methods (salted, sun-dried, chemical preservatives, raw) and cleanliness (the raw hide is covered with blood, feces, dirt, etc.)).
Raw hides vary from region to region, and their characteristics will affect the application rate of probiotic biochemical products. In addition to the characteristics of raw hides, each tannery will follow a unique process to produce the required leather. This includes the brand and quantity of chemicals used in each stage; the processing time of each stage; machinery (drums and paddles); drum rotation speed; water-saving methods; mechanical actions; ); environmental regulations; methods of preserving hair or hair-dissolving systems; type of tanning (chrome or plants); presence of sewage treatment plants; and climate. Each of these characteristics will affect the application rate of probiotic biochemical products.
The performance of probiotic biochemical products is as good as the best chemicals/enzymes, and they are flexible in application. They can be used in a wide range of pH and temperature and are harmless (safe for tanners and leather product consumers). The diagram on page 25 describes each product used in the test and its effect on the leather.
They can be applied at different stages of the leather manufacturing process. The benefits of Beamhouse are as follows:
The benefits of the wet end process described in this study are:
The variables that affect the results are the chemicals that have been used in the tannery, the source of hides, preservation methods, mechanical effects, etc. The COD process using probiotic biochemical substances is collected from the wet salt cowhide test, and the result is better.
From wet salted rawhide to finished leather, the potential reduction of COD in the whole process is as high as 24%.
The breakthrough probiotic technology can achieve unparalleled processing results in all walks of life without affecting the environment. Natural ingredients from renewable sources and metabolites of the proprietary fermentation process of probiotics have hydrophilic properties, which can delay the damage caused by bacterial spoilage and the unpleasant smell produced.
These qualities provide tanners with an excellent opportunity to replace some chemical additives based on the chemical synthesis of oil derivatives with natural, biodegradable and sustainable alternatives without modifying the existing manufacturing process. .
The continuous operation of using probiotic technology to prepare raw hides for tanning and tanning improves the quality of leather products, saves water and costs, and reduces the impact on the environment.
Compared with traditional chemical additives, probiotic biochemical agents can transfer water molecules to the smallest gaps in the fibril collagen structure up to the protein chain, dissolve and disperse substances that are not suitable for transformation in leather, dissolve organic materials and improve Absorption of agents that give the final leather properties.
This work demonstrates the potential of probiotic biochemical substances in different stages of leather manufacturing to improve leather quality and reduce wastewater pollutants.