The purpose of this study is to evaluate the effects of increasing sewage sludge as a fertilizer on the stimulation of biological processes and the rate of bioremediation of fatty substances in soils contaminated with this substance in the effluent of chemical companies. Industrial wastewater, especially the chemical industry, is one of the largest volumes of industrial wastewater producers. The chemical industry in general around the world produces more than ۱.۴ million barrels of contaminated sludge per day, which is a major environmental hazard. If the environment is not considered in the design and operation of industrials, in addition to environmental problems related to air and soil pollution, it will cause surface and groundwater pollution, the scope of which can affect the next few generations. Therefore, several solutions have been proposed for the treatment of contaminated wastes, which are mentioned in this study. Due to limited soil and groundwater resources, soil pollution is one of the most important environmental problems in the world. For this purpose, methods such as direct engineering methods or natural cleaning, i.e. without human intervention in modifying this control, reduce or eliminate pollution from the environment by increasing biological activities of the environment. Also, by using methods that accelerate the decomposition of pollutants such as usage of nitrogen and phosphorus organic matter and plowing for better soil aeration increasing microbial activity is accelerated.