The problem of the purification of sulphite spent liqour adn slop by means of the alcoholic fermentation and fodder yeast growth is investigated by many authors The publication discusses the ability of the strains Candida Berkhout to ferment hexoses and pentoses, as well as to grow on sulphite spent liqour and slop and to produce the Single Cell Protein. The decrease of BOD and the degreee of the sulphite spent liqour purification is discussed. Attempt of the utilization of black liqour from the straw pulp mill on the biochemical way is reported. Own investigations and literature survey are presented. 63 tables and 22 figures are included. 274 references