Investigating spatial variation of Arsenite concentrations into river Awoja, physiographic determinants and treatment options

Abstract

The 2030 agenda of the United Nations placed a high priority on addressing water quality challenges. Many towns and cities are supplied with water from rivers. Depending on the human activities on the catchment, the water from the river can be characterized by the presence of Arsinite. It is important to quantify Arsenite to guide in planning for the water treatment. In this study, several points were selected within River Awoja catchment. Rainfall runoff was sampled at selected locations and concentrations of Arsenite was determined from a laboratory. To explain the spatial variation of Arsenite concentrations, analysis of land categories was conducted. The potential of rice husk as Activated Carbon in removing Arsenite was investigated. The concentrations of Arsenite ranged from 20.21mg/L to 27.57mg/L against WHO standards of 0.01mg/L indicating the need to treat the water given the substantial level of pollution with Arsenite. The linear relationship between physiographic characteristics and Arsenite-based land categories of barren land, grassland, settlement, cropland, waterbody, wetland and woodland characterized in terms of coefficient of determination (R2), yielding R² values of 0.80, 0.84, 0.86, 0.76, 0.62, 0.76 and 0.61, respectively. The efficiency of Arsenite removal using rice husks as Activated Carbon improves as dosage and contact time increase. This study demonstrated that Arsenite concentration at sampled points is higher than the WHO limit and that Activated Carbon has the potential to remove Arsenite with efficiency of about 78%.