Kinetics of biodegradation of total petroleum hydrocarbon in diesel contaminated soil as mediated by organic and inorganic nutrients

Abstract

In this study, the kinetics of biodegradation of total petroleum hydrocarbon (TPH) in diesel contaminated soil as mediated by organic [cow dung (CD), poultry waste (PW), and pig dung (PD)] and inorganic (ammonium chloride, trypton X and sodium nitrate) nutrients was determined. Spread plating method was used to quantify the bacterial and fungal communities and their identification done using macroscopic, biochemical and microscopic techniques. The kinetics of biodegradation study involves TPH determination using gravimetric method and first order kinetic models. The results revealed the presence of bacterial and fungal species namely: Pseudomonas sp., Aeromonas spp., Corynebacterium sp., Serratia spp., Citrobacter spp., Rhizopus sp., Aspergillus spp., Fusarium spp., Geotrichium sp., Sacharomyces sp. and Mucor sp. Samples amended with organic wastes showed higher increase in all the microbiological parameters while the inorganic wastes has a lower count in all the parameters with only Trypton X trying to compare favourably with the organic waste (CD) in the treatment Groups. The result of the TPH showed significant percentage reductions of TPH content in all the treatments with PD and PD having the highest and lowest reductions of 92.56 % (3, 541.08 mg/kg) and 92.17 % (3, 729.95 mg/kg) in comparison with the unamended sample (control) which showed significantly reduction of 58.00 % (20, 000 mg/kg). Thus, the technology used in this study offers a promising, better, cheaper and more eco-friendly system that if adequately applied in diesel polluted soil will lead to non-toxic environment for plant, animal and general public.

Keywords: Bacteria, Biostimulation, Diesel pollution, Biodegradation kinetics, Organic and inorganic nutrients