Revista de biorremediación y biodegradación

Abstracto

The Effect of Soil pH on Bioremediation of Polycyclic Aromatic Hydrocarbons (PAHS)

Rakesh M. Pawar

Environmental fate of polycyclic aromatic hydrocarbons (PAHs) is a significant issue raising interest in bioremediation. Soil microorganism plays a vital role in degradation of PAHs and uses various metabolic pathways for degradation process. The effect of soil pH on degradation of PAH with a view to manipulating soil pH to enhance the bioremediation of PAH’s was studied. The degradation rate of key PAHs (phenanthrene, anthracene, flouranthene, and pyrene) was monitored in an Arthur Brower’s topsoil at range of soil pH (5-8). Isolation of microbes degrading PAHs was carried out. L-arginine ammonification was measured to estimate soil microbial biomass by ATPase, whilst soil enzyme associated with the degradation rate of each individual PAH was studied. It was observed that soil pH 7.5 was most suitable for the degradation of all the PAHs. 50% degradation was observed in soil pH 7.5 within first three days of time period which is a seventh of the time taken at pH 5 and pH 6.5 (21 days). Greater fungal populations were found at low (acidic) soil pH and also at high (basic) soil pH, in comparison with neutral pH 7. Pencillium species was found to be more prevalent at acidic pH whilst Aspergillus species was found to be more prevalent at pH 7.5-8. Greatest bacterial population was observed at soil pH 7.5. Moreover, the practical application to bioremediation process that natural detoxify PAHs and different organic compounds present at various contaminated sites is at slower rates and thus requires potential understanding in degradation improvement. However, amending the favorable soil pH as a result of its effect obtained in this study will fasten the rates of PAH degradation. Since, greatest degradation rates in this study were found at soil pH 7.5 suggesting that liming to increase soil pH, may significantly increase bioremediation rates.