The use of biotechnology allows a lot of benefits for industries. Some benefits are: commonly the biotechnological processes or reactions occur at low atmospheric pressure and at low temperatures; the procedure has a high space-time product, and renewable components.
Biotechnological processes used in leather production, offering the reduction of adverse environmental impact of the activity. Currently, tanneries utilize high quantities of harmful products and water, like sulfide and chromium, produce a high level of solid garbage that could be better treated or reused and sewage that must be treated. In leather production, mostly applied enzymes, can be used in different steps of procedure: soaking, unhairing, dyeing, degreasing, and bating or in sewage and solid wastes treatment.
Biotechnology has been applied in tanning industry for some years. Presently, most of enzymatic preparations for tanning industry do not contain adequate specificity. The principal benefit of the enzyme soak are shorter wetting time, superior fiber opening, solubilization and reduction of carbohydrates, fat and proteins.
Enzymes can be utilized too on un-hairing methods, on hair removal and epidermis, removal of remaining elements, reduction on effluent load, and dispersion or removal of adipose components. It is observed that enzyme does not hydrolyze the collagen and has effectively hair removal, preserving the same conditions such as same pH and same time of conventional unhairing method, but without applying sulfide.
Enzymatic treatment can be applied too on wastes produced during the leather procedure. For not tanned garbage, can be applied proteolyses enzymes, alkaline and neutral, producing hydrolysates rich in proteins and fat, in temperature within 50°C. To tanned garbage, having chromium, can be found three fractions: the coagulated material containing chromium, hydrolysated collagen and proteins.
Two processes of liming and soaking are developed, one of these was entitled enzyme-assisted test, utilizing enzymes and chemicals and the other was entitled conventional test utilizing only chemicals. The experiments were carried out at laboratory scale in barrels. Two types of fluid enzymes, called lipase A (AL) and protease A (AP) were supplied. More two experiments were performed with only one of these enzymes. The chemicals used in biochemical analysis and leather processing were of analytical and commercial grade, respectively.
The process time to the phase of soaking such as enzyme-assisted soaking is four hours and for conventional soaking was five hours. The process time to the liming phase is lasted for 12 hours for the both enzymatic process as for traditional process.
The chemicals and enzymes use in both methods, enzyme-assisted and traditional, in the soaking phase with the proportion of use calculated on weight of the hide (about 250g of both samples). Each test is carried out from the starting.
In soaking phase the chlorides concentrations in waste water and the element of extractable materials with dichloromethane from hides are analyzed.
In the liming step, the weight percentages of resultant materials are added. Scanning electron microscopy (SEM) analyses are used according to show the variations between the outcomes of each method.
Based on the chloride deduction analysis in the soaking waste water, it's potential to understand that the time of the process is a variable which has a huge significance, mostly to the traditional method, that show a higher confidence on it to attain removal values nearer to the ones get on the enzyme-assisted method.
Moreover, it's apparent that the enzymes increase speed the hide wet method because it assists to open collagen fibers formation. The conventional method improves a lower capability of the fat removal in soaking, because the hides prove irrespective of the time, higher levels of fat. From the investigation of SEM images, it's potential to understand that the liming method that applies more enzymes is more effective in unhairing, because enzymes eliminate the hair from root, leading little harm to its formation, while the conventional method supports the degradation of hair composition.
The enzymatic hydrolysis tests of chromed leather shaving waste illustrate the maintenance of a solid stage rich in chrome, where average mass reduction effectiveness is 53.7%. From the outcomes of bacterial treatment it can be showed that Pseudomonas aeruginosa, the bacterial species lives in the environment having the chrome leather garbage, with no requirement for the pH adjustment. The bacteria eliminate the chrome present in garbage; conversely, the addition of sucrose formulates the process more efficient and more favorable.
So, biotechnology can be applied in leather manufacturing and it will play a great role for the reduction of contamination, principally, of water and soil.
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