Soil Corrosivity Under Natural Attenuation

This study investigated natural attenuation conducted in soil artificially contaminated with low-sulfur diesel oil, and to evaluate the corrosion of ASTM A36 carbon steel (A36) during the bioremediation process. Microbiological quantification of hydrocarbonoclastic bactéria (HCB) and heterotrophic bacteria (Aerobic and Anaerobic) was carried out at 7, 14, 28, 42 and 56 days. Corrosion rate was quantified according to the NACE-SP-07-75 standard using the gravimetric method. Morphological analysis was conducted through Scanning Electron Microscopy. Results indicated a significant reduction of 24.03% in oils and greases in the soil, along with a respirometric degradation of 11.10%. Soil contamination with diesel led to microbial growth, mainly of HCB, during diesel bioremediation; however, there was no impact on the corrosion rate of A36. Soil corrosivity with diesel was classified as low after 56 days of experiment. These findings show that natural attenuation is a method capable of bioremediating soil with diesel without impacting nearby steel structures.

Keywords:
Corrosion; bioremediation; natural attenuation; diesel oil, ASTM A36 steel