I.E UWIDIA

Kola (Cola nitida) leaves are widely known for their ethnobotanical uses, yet their by- products remain underexplored as sources of bioactive compounds for environmental applications. Fermentation of plant-derived substrates often enhances their physicochemical profile, making them useful in biostimulation processes that support microbial activity for pollutant degradation. Against this background, this study investigated Cola nitida whey, focusing on its extraction, fermentation behavior, and nutrient composition, with the aim of assessing its potential application as a bioremediant. Fresh kola leaves were processed through washing, grinding, boiling, and filtration to obtain whey, which was digested with nitric acid and subjected to physicochemical analysis. Parameters evaluated included pH, electrical conductivity (EC), moisture content, total organic matter (TOM), total organic carbon (TOC), nitrate, phosphate, nitrogen, phosphorus, and potassium. Results showed dynamic changes across the five- week fermentation period. pH decreased initially from 5.29 in Week 1 to 5.18 in Week 3 before rising to 6.01 in Week 5, while EC steadily increased from 1595.50 to 2129.50 µS/cm, reflecting ionic release. Moisture content rose from 92.08% to 94.09%, whereas TOM and TOC increased overall, with TOM ranging from 54.06 to 106.55% and TOC from 31.36 to 61.80%. Nutrient levels indicated progressive mineralization: nitrate rose from 174.16 to 1152.36 mg/kg, phosphate from 411.67 to 971.81 mg/kg, nitrogen from 39.56 to 261.06 mg/kg, and phosphorus from 122.75 to 295.46 mg/kg. Potassium fluctuated but stabilized at 2.55 mg/kg by Week 5. These findings suggest that kola-leaf whey develops enriched organic and mineral content during fermentation, creating a nutrient-rich medium favorable for microbial proliferation. The shift toward near-neutral pH at later stages further supports microbial activity, while the elevated nitrate and phosphate levels highlight its suitability as a low-cost, plant-derived stimulant for bioremediation, although regulated application is recommended to minimize eutrophication risks.

Crude oil spills in Nigeria poison farmland, killing plants and microbes while adding dangerous hydrocarbons and heavy metals that hurt crops and human health. This study tests a low-cost, eco-friendly fix using fermented whey from guinea grass (Panicum maximum) leaves to boost soil microbes that eat oil. The aim was to see how well this whey cleans oil-polluted soil by cutting total petroleum hydrocarbons (TPH) and restoring soil quality. The scope included collecting leaves (Panicum maximum) from University of Benin sports complex, processing the leaves into whey and fermenting the whey at various periods for twelve days. The whey samples were further characterized to further determine pH, electrical conductivity, moisture, organic matter, carbon, nitrate, phosphate, nitrogen, phosphorus, potassium, and microbial counts to evaluate the whey with the best potential with respect to fermentation time—day 12 with pH 5.74, EC 4804 µS/cm, TOC 67.27%, nitrate 394.17 mg/kg, and high microbial growth (819 CFU/ml at 10⁻¹). Bioremediation potential of the whey was evaluated by treating agricultural soil. The day-12 whey results showed that soil treated with 200 ml was best, raising pH from 5.21 to 7.19, nitrogen from 19.10 to 27.18 mg/kg, phosphorus from 12.65 to 14.98 mg/kg, potassium from 6.23 to 12.45 mg/kg. TPH results showed that hexatriacontane rose to 1.17mg/L increased in the treated soil compared to the untreated contaminated soil, indicating its formation as a biodegradation intermediate during the breakdown of heavier hydrocarbons. Hexatriacontane showed a significant reduction to 0.05mg/L after whey treatment, demonstrating effective microbial attack on heavy hydrocarbon fractions. Heavy metals analysis indicates a significant reduction in metal concentration as in iron from 45.67mg/kg to 32.45mg/kg, zinc 18.90 mg/kg to 12.34 mg/kg copper 7.56 mg/kg to 5.12 mg/kg. Day 12 fermented Panicum maximum whey gave the best remediation potential.