Oil contamination of soils is one of the most serious environmental problems that require developing effective and cost-efficient remediation methods. Biological approaches, particularly bioremediation using organic ameliorants, are of special interest as they can activate the indigenous microflora and accelerate pollutant degradation. One promising material for the bioremediation of oil-contaminated soils is thermally treated granulated sewage sludge (granulate). It contains microorganisms, organic matter, and biogenic elements, which warrants an assessment of its efficacy in the remediation of oil-polluted soils. A model experiment was conducted for the first time studying the granulate effect on the remediation parameters of an oil-contaminated grey forest soil. These parameters included respiratory activity, the eco-physiological status of the microbial pool, and the efficiency of total petroleum hydrocarbon (TPH) degradation. The research encompassed three remediation approaches: technological, microbiological, and phyto-microbiological. The study established that 2 % and 4 % granulate application significantly enhanced both the basal and substrateinduced respiration of the contaminated soil. The maximum CO2 emission was observed in the phyto-microbiological remediation trials with 4 % granulate. It was shown that the use of granulate in samples with low TPH content (up to 3.7 g/kg) did not intensify their degradation. The highest TPH degradation efficiency (a 69–79 % reduction from
the initial content) was achieved at a contaminant concentration of 4.4–15.4 g/kg in the microbiological remediation experiment with 2 % granulate. We conclude that the application of 2 % granulated sewage sludge provides an optimal “degradation efficiency / CO2 emission” ratio for soils with a TPH content exceeding 3.7 g/kg. This leads to maximum pollutant breakdown with a minimal increase in carbon dioxide emissions. The cultivation of higher plants did not yield a significant additional effect, indicating the promise of applying the technologically simpler microbiological approach with 2 % granulate for the remediation of oil-contaminated soils.
ISSN 1995-4301
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