Activated Sludge Acceleration Agent   Activated Sludge Acceleration Agent Biostimulation, which employs nutrients to enhance the proliferation of indigenous microorganisms and therefore the degradation of contaminants, is an effective tool for treatment of oil-contaminated soil. Biostimulation promoted the proliferation of bacteria, with Gammaproteobacteria showing the greatest increase. However, the proliferation of fungi was inhibited by the accumulation of the degradation products.