Seasonal variation on the effect of heavy metals (chromium and zinc) on the corrosion potential of desulfovibrio desulfuricans and desulfovibrio vulgaris on three metal coupons (stainless steel, mild steel and carbon steel) in ndoni river.

Seasonal variation on the effects of heavy metals (chromium and zinc) on the corrosion potential of Desulfovibrio desulfuricans and Desulfovibrio vulgaris on three metal coupons (stainless steel, mild steel and carbon steel) in Ndoni River was carried out for a period of one year between April 2017 to March 2018.The River is a fresh water ecosystem where sulphur reducing bacteria can be found. Desulfovibrio desulfuricans had its highest growth rate in the dry season at 28MPN/100ml and highest growth rate in rainy season at 22MPN/100ml while Desulfovibrio vulgaris had its highest growth rate in the same dry season at 26MPN/100ml and highest growth rate in the same rainy season at 19MPN/100ml.The heavy metals (chromium and zinc) were present at a level tolerated by the organisms in the dry season at (1.08mg/l and 1.46mg/l) respectively while the levels of chromium and zinc at the beginning of rainy season were at 0.87mg/l and 1.10mg/l respectively. The corrosion rates of the three metal coupons stainless steel, mild steel and carbon steel were also highest in the dry seasons namely 0.127g, 2.271g, and 4.291g respectively. The TTEST value for chromium(stainless steel, mild steel and carbon steel) are 0.000598, 3.65947E-05 and 4.53205E-06 respectively while that of zinc(stainless steel, mild steel, and carbon steel) are 2.63664E-05, 0.004315319 and 7.74988E-05 respectively. The Correlation value between stainless steel and mild steel was 0.102427567.The Correlation value between mild steel and carbon steel was 0.146927782 while the Correlation value between stainless steel and carbon steel was 0.990278275.