Biodiesel from waste fat generated by the tanning industry

Abstract

Fleshings, the main non-tanned solid waste of the tanning industry, are produced during the fleshing operation, which is the mechanical removal of subcutaneous fat and connective tissues. Relatively high content of fat and low (often even negative) price make fleshings a potential feedstock for biodiesel production. However, said benefit is reduced by the fact that the fleshings must be refined, i.e. it is necessary to remove residual sodium chloride, water, subcutaneous tissue (protein), and in many cases free fatty acids. The operating costs of the refining technology must not exceed the price of a traditional material that is vegetable oil. Another complication is associated with the relatively small production of tannery fats, which considerably extends the return on investment. To overcome these disadvantages it is necessary to optimize the refining operations and acquire secondary products of high utility value. The first task is related to using theoretical tools of process engineering that enable management of each refining process at low operating costs, the second task includes production of protein hydrolysates obtained from the hydrolytic treatment of subcutaneous tissue and processing of free fatty acids into commercially interesting products.