Bio-remediation of crude oil-contaminated soils in Eleme, Ogoni-land using CLOGEN, MicroSORB®, PRP® and a combination of Electro-Kinetic Action+KEEN®+Ors-SORB plus®

This study evaluated the efficiency, effectiveness and ecological impacts of bio-stimulation, bio-augmentation, and electro-bio-remediation interventions in phase-1 Ogoni-land remediated areas, focusing on the rate of Total Petroleum Hydrocarbon (TPH) degradation, soil health, soil physicochemical and biological properties across four selected locations in Eleme, using CLOGEN, MicroSORB®, Petroleum Remediation Product® and a combination of Electro-Kinetic Action plus KEEN® and Ors-SORB plus®. Nkeleoken Alode LOT 04 with the largest total area of 0.64Ha and remediated soil volume of 46,100m3 using Electro-Kinetic Action + Ors-SORB plus® + KEEN® had initial TPH value of 2,021 mg/kg reduced to 265 mg/kg, showing significant degradation with 86.89% efficiency with 13.11% residual hydrocarbons left in the soil, while Elelenwo Manifold, Akpajo LOT 46 with moderate total area of 0.3943Ha and soil volume of 12,100m3; a smaller area compared to LOT 04 had higher efficiency in TPH degradation, highlighting the effectiveness of CLOGEN® with 99.61% degradation leaving behind 0.39% residual contamination; where initial TPH value of 6,600 mg/kg was reduced to 26 mg/kg, showing the most efficient location, cleanest site, post-remediation, and high level of restoration. Ajeokpori Well 3, Okuluebu LOT 54 with smaller area of 0.0854Ha and moderate soil volume of 8,300m3 demonstrated a localized remediation effort with a focus on smaller-scale impact, where initial 4,550 mg-TPH/kg-Soil was reduced to 1,187.87 mg-TPH/kg-Soil, indicating 73.89% efficiency of MicroSORB®, with 26.11% residual contamination left in the soil after-remediation, while New Elelenwo Manifold, Akpajo LOT 56 with a medium area of 0.4139Ha and small soil volume of 9,600m3; balancing land coverage and soil volume for remediation, had initial TPH value of 5,600 mg/kg reduced to 402.29 mg/kg, highlighting degradation efficiency of 93.06% with 6.94% residual hydrocarbons still left in the soil after-remediation, showing a strong performance of PRP® and also representing a high level of restoration. Laboratory analyses of soil microbial count in bio-remediated locations show mean values for THB and THF of 417,000±0.9578622 and 36,000±0.5244044, and HUB and HUF of 4,125±0.5452446 and 2,800±0.1290994; while macronutrients of Nitrogen (N), Phosphorus (P), and Potassium (K) showed marked improvements in remediated areas post-bio-remediation; with N values of 1.091 – 4.299 mg/kg and 1.278 mg/kg for control, K values between 15.423 – 45.789 mg/kg and 0.652 mg/kg for control, and P values of 0.321 – 2.321 mg/kg and 0.639 mg/kg control, with specific locations displaying nutrient levels indicative of enhanced soil fertility. Nutrient distribution variability across the sites suggests that, while some areas have shown significant soil improvement, others may require site specific targeted interventions for uniform ecological restoration.