Evaluation the Capability of Isolated Bacteria from Stabilized Compost for Bioremediation of Pyrene and Phenanthrene from Contaminated Soil with Municipal Solid Waste Leachate

Introduction: Pyrene and phenanthrene are polycyclic aromatic hydrocarbons (PAHs) are priority pollutants. The aim of this study was to investigate the ability of isolated bacteria from stabilized compost‌ for biodegradation of pyrene and phenanthrene from soil contaminated with municipal solid waste leachate. Materials and Methods: In this study, phenanthrene and pyrene were selected as priority PAHs pollutants. The degrading bacteria of these compounds were isolated from the stabilized compost and their ability to remove different concentrations of pyrene and phenanthrene investigated. The remaining concentrations of pyrene and phenanthrene were measured by GC-MS. The growth kinetics of bacteria were also studied using a spectrophotometer at 595-nm wavelength. One-way ANOVA was used to determine the statistical significance and plot the related curves, and the Excel software and SPSS version 24 to do statistical analysis. Results: The most potent bacteria in removing pyrene and phenanthrene were Paenibacillus and Bacillus, respectively. The concentrations to be studied were determined as 10, 25, 40 and 55 μg/kg according to the concentrations of PAHs in the soil contaminated with municipal solid waste leachate. At constant temperature of 30 °C after 30 days at these concentrations, the removal efficiency was, respectively, 96.3%, 83%, 77.8%, and 72.4% for pyrene and 100%, 99.6%, 95.9%, and 94.6% for phenanthrene. The growth kinetics of phenanthrene-exposed bacteria were better than those of pyrene-exposed bacteria. Conclusion: The results show that bacteria in stabilized compost are able to remove pyrene and phenanthrene. The bacteria of the highest efficiency for removal of pyrene and phenanthrene are Paenibacillus and Bacillus, respectively.