Badania laboratoryjne wpływu dodatku γ-PGA na efektywność biodegradacji węglowodorów ropopochodnych

The article presents issues related to the biodegradation of petroleum hydrocarbons (TPH – total petroleum hydrocarbons, BTEX – monoaromatic hydrocarbons, PAH – polycyclic aromatic hydrocarbon) in soil by inoculation with a biopreparation based on autochthonous bacterial strains and mixtures of biopreparation with γ-PGA solution. The biodegradation tests were carried out in laboratory conditions with the use of the Oxi-Top kit. The test material was soil collected from the mining pit, characterized by high concentrations of petroleum hydrocarbons. In the biodegradation tests, four inoculation variants were applied: variant A (bioprepara-tion), variant B (biopreparation and γ-PGA solution in a 2: 1 volume ratio), variant C (biopreparation and γ-PGA solution in a 1: 1 volume ratio) and variant D (biopreparation and γ-PGA solution in a 1: 2 volume ratio). The biodegradation efficiency was assessed on the basis of respirometric tests and chromatographic analyzes. The values of microbial activity in soil samples inoculated with the biopreparation and the γ-PGA solution after 60 days of the test were 2,040 mg O₂/dm³ (variant B), 3,769 mg O₂/dm³ (variant C) and 5,127 mg O₂/dm³ (variant D), while in the sample inoculated with the biopreparation alone 1,582 mg O₂/dm³ variant A. The chromatographic analyzes carried out showed that the degree of TPH biodegradation after the end of the test was 36.78%, while the addition of γ-PGA to the biopreparation reduced the TPH content by 39.73% (variant B), 42.37% (variant C) and 44.34% (variant D). The degree of BTEX biodegradation in soils inoculated with the biopreparation with the addition of γ-PGA ranged from 47.11 to 51.00%, while in the variant without the addition of γ-PGA it was 44.53%. In turn, soil inoculation with the biopreparation with the addition of γ-PGA reduced the PAH content in the tested soil by 32.18% (variant B), 37.40% (variant C), 39.62% (variant D), and the biopreparation itself by 29.40% (variant A). Laboratory tests have shown that γ-PGA positively affects the efficiency of biodegradation process of petroleum substances such as aliphatic hydrocarbons, monoaromatic hydrocarbons and polycyclic aromatic hydrocarbons.