Coupling biostimulation and phytoremediation for the restoration of petroleum hydrocarbon-contaminated soil

Total petroleum hydrocarbons (TPH) continue to be among the most common pollutants in soil worldwide. Bioremediation and phytoremediation have become sustainable ways of dealing with TPH contamination and biostimulation-assisted phytoremediation is considered as a potential approach for the treatment of pollutants. In this study, the response surface was used to optimize the single-factor biological stimulation experiment of moisture content, leavening agent content and compound fertilizer content and got the best experimental plan of biological stimulation. It was found that TPH degradation rate was 28.6% by biostimulation after 70 days. Further, from 20 kinds of plant seeds, 5 kinds of suitable or growth and high germination rate were selected for petroleum hydrocarbon degradation experiment. In the phytoremediation, peanut was selected as the best plant species by measuring the TPH degradation rate, bacteria count, growth of test plants, germination rate and amount of catalase in the soil and it could achieved 31.1% degradation rate of petroleum hydrocarbons after 70 days. Finally, the artificial biostimulation and phytoremediation combined degradation experiment of petroleum hydrocarbons-contaminated soil was designed and it achieved 38.9% TPH degradation rate after 70 days. NOVELTY STATEMENT In petroleum hydrocarbon-contaminated soils, single remediation methods are often limited and may be disturbed by environmental conditions. In the actual research process of coupling biostimulation and phytoremediation, it is necessary to play the role of microorganisms on the premise of ensuring plant growth. This may further present challenges for combined bioremediation attempts. In this work, the response surface methodology was used to optimize the single-factor biological stimulation experiment of moisture content, leavening agent content and compound fertilizer content. As a result, the best biological stimulation experimental scheme can be obtained to repair oil contaminated soil. Then, biostimulation-assisted phytoremediation degradation experiment of petroleum hydrocarbons-contaminated soil was designed and an effective degradation rate of petroleum hydrocarbons in the soil was obtained.