Biocorrosion Study of Mild Steel in Dumpsite Leachates

Abstract

Biocorrosion due to dumpsite leachates can lead to rupture and failure of engineering materials such as mild steel. This study was carried out to assess the effect of dumpsite leachates in corrosion process of mild steel. Mild steel coupons were prepared and immersed completely in leachates from Olusosun dumpsite (A), Ewu Elepe dumpsite (B) and Abule Egba dumpsite (C). The following parameters were measured at regular interval in each of the leachate: Total Dissolved Solids (TDS), Conductivity, pH, Temperature and Dissolved Oxygen (DO) using a multi – parameter water quality monitor and Total Bacterial Count (TBC) using standard method for biological analysis of water flood injection water. The corrosion rate was determined using weight loss method. The results revealed that the weight loss varied between 0.27 and 0.58 g in leachate A, between 0.05 and 0.29 g in leachate B and between 0.02 and 0.50 g in leachate C. Corrosion rate varied between 2.35 and 7.61 mm/yr in leachate A, between 1.15 and 1.48 mm/yr in leachate B and between 1.48 and 7.03 mm/yr in leachate C. Leachate A has the highest range of TDS ranging between 18, 686 and 125, 856 mg/L as well as highest range of Conductivity ranging between 8.62 and 57.75 µS/cm. Moreover, leachate A has the highest range of pH ranging between 5.11 and 5.34 while it has the least range of DO varying between 2.94 and 3.59 mg/L. Leachate B has the highest range of temperature varying between 27.60 and 32.30°C. Leachate C has the least range of TBC ranging between 100 x 103 and 126 x 103 Cfu/ml. The leachates from dumpsites have the potential to cause corrosion of mild steel due to the presence of bacterial in the leachates. It was recommended that dumpsites should not be cited where there are pipelines.