A study required for the use of biosolids amendment for the remediation of oil contaminated soil was performed. The amendment was prepared by the cultivation of oil degrading bacteria using biosolids, and its effectiveness in remedying oil contaminated soil was evaluated. A study to remove the hazardous materials, such as heavy metals and pathogens, contained in biosloids was also performed to relief the riskiness when the amendment were applied to soil. For the studies on the preparation of the biosolids amendment, and its effectiveness for the remediation, functional microbial consortium was cultivated from biosolids mixed with total petroleum hydrocarbon (TPH) and sawdust in the first set of experiment. Further, the mixture was maintained by a humidifier over a period of 4 weeks to reduce the water loss. After the well growth of functional microbial consortium, the biosolids mixtures were applied to artificial oil contaminated soil and natural oil contaminated soil to test the TPH degradation. The application of biosolids mixture was more effective in artificial oil contaminated soil than the natural oil contaminated soil. The TPH concentration was rapidly reduced over 80% within a period of 7 days after biosolids mixtures application. However, in the case of natural oil contaminated soil, less than 2000 mg/kg TPH was remained after 65 days of biosolids mixtures application. For the study to remove heavy metals and pathogens contained in biosloids, phosphate amendments and ultrasonic treatment were used to immobilize the heavy metals and remove the pathogens from the biosolids. Potassium dihydrogenphosphate was used as a source of phosphate for metals immobilization. Before and after phosphate amendments, metal concentration in biosolids was analyzed by EPA 6010, EPA 3051 and selective sequential extraction methods for comparison of the results. The results showed that 50% of the metals immobilized by phosphate amendments. In addition, extractable level of metals was different in different methods. Ultrasonic treatment was used to increase the metal phosphate reaction as well was pathogens removal from biosolid. Two approaches were used in this experiment, at first phosphate amendments followed by ultrasonic treatment and at second ultrasonic treatment followed by phosphate amendments. Biosolids were treated ultrasonically in both experiments for 1hr by ultrasonic pipette washer machine. The results showed that biosolid treated with ultrasonic followed by phosphate amendments have higher metal immobilizing efficiency than the other method. Finally, pathogens could be removed from biosolids using ultrasonic treatment.