Physicochemical and Geotechnical Properties of Bioremediated Oil Sludge-Contaminated Soil

Authors: Alhassan, M.K.

DOI Info: http://doi.org/10.5281/zenodo.21047568

ABSTRACT

Oil sludge contamination leads to profound geoenvironmental challenges by changing the physicochemical and geotechnical properties of soil. Thus, cheap and sustainable remediation techniques are required to reclaim the capacity of contaminated soil. This study assessed the potential of using a biostimulant to: (i) activate indigenous microorganisms for decontamination and (ii) evaluate the suitability of the bioremediated soil for civil engineering applications. The study was carried out in two stages. Stage 1 included mixing contaminated soil with liquid chicken manure (CM), which was obtained from 0, 2.5, 5, 7.5, and 10% CM by dry weight of soil, and keeping it in microcosms for 30 days. Stage 2 investigated the physical, chemical, bacteriological, and geotechnical properties of the bioremediated soil. Oil degradation was determined using total petroleum hydrocarbons (TPH) concentration. Parameters evaluated included carbon, nitrogen, phosphorus, temperature, pH, optimum moisture content (OMC), maximum dry density (MDD), and unconfined compressive strength (UCS) at curing periods of 7, 14, and 28 days. Results showed that Bacilli species, Rhodococcus, Arthrobacter, Acinetobacter, and Pseudomonas species were the dominant microorganisms in the treatments. At 10% CM treatment, the TPH concentration, organic carbon, and OMC decreased from 12.41%, 78 g/kg, and 18.38%, to 5.4%, 40 g/kg, and 12.6%, respectively. Nitrogen and phosphorus increased to 0.87 and 0.063%, whereas pH attained 7.65 at 7.5% CM treatment. Temperature, MDD, and UCS value increased to 32°C, 1.46 Mg/cm3, and 208 kN/m2, respectively. These demonstrate the effectiveness of chicken manure in the remediation of oil sludge for civil engineering applications.

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