Occurrence of iron in bank filtration wells: case studies in Ituporanga (SC) and Garanhuns (PE)

摘要

Bank filtration (BF) is a simplified alternative water treatment, which is the abstraction of water through wells near the banks of surface water located in alluvial aquifers. The chemical composition of the aquifer interferes in the treated water quality by BF technique, and in some cases may promote the appearance of contaminants, such as iron. The objective of this study is to evaluate the occurrence of iron in BF wells in two regions of Brazil, Ituporanga (SC) and Garanhuns (PE), seeking to connect the local conditions to the iron transfer process of soil/subsoil to water. In order to assess the water quality, physical and chemical analyses were performed for raw water, such as the water from the BF wells in both locations. The iron concentration in the water from BF was superior to the surface water in both locations. Although Garanhuns is located in a region with low iron content in the soil, the BF well water showed higher concentrations of this metal than the BF well water in Ituporanga, located in a region with high iron concentrations in the soil. Both sites showed favorable conditions for the transfer of iron present in the soil to the water, through the reduction processes. In Garanhuns, reducing conditions were more intense which allowed for the transfer of a larger amount of iron to the BF water.