The main objective of this research program; was the reduction of the pollution degree of wastewater resulted from the meat processing industry, using chemicals methods. We focused of the decolorisation of the slaughtering wastewater using the coagulation methods. As we well known, the main pollution agent in the slaughtering process is blood, which coagulates and precipitates in the presence of alumina and iron salts. The research program wants to proof the method efficiency and to determinate the optimum parameters of the process.