Evaluation Of Corrosion And Encrustation Potentials Of Groundwater Wells In Calabar Area, Southeastern Nigeria

Abstract

This article presents results of groundwater quality assessment based on some corrosion-encrustation index parameters (CEIP) and drinking water standards. The CEIP concentration results indicate that the hydrogen ion concentration, pH ranges from 5.4 to 7.6, total iron, Fe varies from 0.02 to 3.0mg/l; Manganese Mn concentration was found to be from 0.01 to 1.0mg/l; the total dissolved solids TDS content of 13.0 to 273.7mg/l; Dissolved oxygen DO of 0.4 to 6.2mg/l; Hydrogen sulphide H2S of 0.01 to 2.5mg/l; Chloride Cl of 2.6 to 16.2mg/l and bicarbonate HCO-3 ranged 20.5 to 80.9mg/l while total carbonate hardness TCH ranged from 2.4 to 8.5mg/l. Corrosion is accelerated from a combination of any two factors such as high concentration of H2S >2.0mg/l; DO >2mg/l; pH <7; Cl- >500mg/l; TDS >1000mg/l and HCO-3 >50mg/l. Encrustation is promoted when TCH >100mg/l; pH>7; Mn >0.1 and Fe >0.3mg/l. Interpretation of these CEIP analytical results based on these background values indicate that the groundwater is acidic. Acidic water causes corrosion of pumps, pipes and screens made of iron and steel. On the other hand, encrustation is never a major problem, although it is not completely absent in the area. The high total iron and manganese content greater than the above threshold values are the causes of encrustation in some localities while the high acidity, dissolved oxygen and bicarbonate are the causes of corrosion in Calabar area. Ways of minimizing the problems of corrosion and encrustation in the water industry of Calabar area have been suggested.

Keywords: Corrosion, Encrustation, Index Parameter, Calabar.

Global Journal of Geological Sciences Vol. 6 (1) 2008: pp. 1-8