The aim of the paper is to determine whether the addition of brown coal and peat influences the rate of the aliphatic substance biodegradation in oily bleaching soil (OBS) by properly selected bacterial strains. OBS was taken from the NZPT (a fat-processing factory); its characteristics were acidity (pH 4.8) and a 14% aliphatic substance content. Laboratory examination showed that a 35% addition of brown coal and peat provided best conditions for the aliphatic substance degradation process. After 44 days of the experiment, the organic substance reduction was 47.1%, and the fat content was reduced to 0.9%. The application of the composite considerably reduced the period of the OBS biodegradation. In order that low-pH fatty waste could be utiliseed with the aid of bacterial strains, it needs to be neutralised beforehand.