The effectiveness of bioremediation of oil-contaminated soils in Ukraine

Abstract

Purpose. To evaluate the effectiveness of phytoremediation (sorghum, millet) and microbial bioaugmentation (Pseudomonas) for cleaning oil-contaminated chernozems of Left-Bank Ukraine in laboratory conditions, using «computer vision» to monitor plant growth and soil changes, with the aim of developing recommendations for recultivation. Methods. 60 kg of black soil contaminated to 46,000 mg/kg (diesel, motor oil) was used. An experiment was conducted with 42 containers (14 groups): control and contaminated, with plants (Sorghum bicolor, Panicum miliaceum, mixture) and Pseudomonas bacteria (“Bionorma”). Phytoremediation, bioaugmentation, and a combined approach were used. Growth dynamics were assessed using the “computer vision” method (Raspberry Pi5, DeepLabv3, YOLOv8, accuracy >95 %). Results. In the control groups, plants formed biomass of 7.5–15.9 g and root volume of 39.7–248.3 cm3, while in the contaminated groups, only 1.8–4.0 g and 9.0–32.7 cm3 due to the phytotoxicity of petroleum products. The combination of sorghum with Pseudomonas bacteria showed the highest efficiency, increasing biomass by 20 % and promoting the biodegradation of hydrocarbons with the formation of organo-mineral aggregates (“dough-like” structure). Computer vision recorded the maximum green mass area (99.6 cm2) and height (16.4 cm) for sorghum with bacteria in contaminated soil, confirming a 50–70 % reduction in phytotoxicity. Replanting in the group with bacteria showed a 30 % increase in biomass compared to the self-cleaning group. Conclusions. Combined bioremediation with sorghum and Pseudomonas bacteria is highly effective for cleaning oil-contaminated chernozems in the Left Bank of Ukraine, reducing toxicity and restoring fertility. The “computer vision” method provides accurate monitoring, reducing the subjectivity of assessments. Black soils have a natural ability to partially self-clean, which is enhanced by microbial bioaugmentation. Prospects include field trials, integration of compost to accelerate processes, and scaling up of digital monitoring to automate reclamation.