Tratamiento y reutilización del baño residual de apelambrado en industrias de curtidos

Tanning industries spend huge amounts of water due to the proccesses taking place since the raw mater incomes till the finished product goes out.The consume of these industries can reach 25 l/hg of raw fur. Nevertheless, waste water coming from some procceses is very contaminant due to its BOD (caused by those parts of the fur not suitable for tanning) and the chemicals added to the baths. So, residual streams from different proccesses contain contaminants that have to be removed befare its dumping. The most contaminant residual bath is that from liming. The principal aims of this proccess is the removing of hair and the outer skin (epidermis). This efluent shows a high BOD and sulphur and lime content, that are the chemicals added to the bath. Many jar-tests have been made to evaluate the possibility of reutilizing this bath. Proteins have to be separated first, this can be made using ultrafiltration membranes. This membranes are able to separate proteins from the waste bath because they cannot come through the membrane due to its size. This way, the stream coming through the membrane shows a composition similar to that of the operating bath and can be reutilized in the proccess. So, an important saving in water and chemicals will be achieved. Numerous tests with differente cut-off and materials membranes have been made. This tests consisted in watching the membrane behaviour with distilled water, ultrafiltrating the liming waste water and, at last, cleaning the membrane to get the initial flux back to the water.