Effective removal of fluoride and arsenic from groundwater via integrated biosorption and membrane ultrafiltration

Abstract

Fluoride (F⁻) and arsenic, present as As(III) and As(V), are widespread toxins in groundwater across India, as well as in other countries or regions like Pakistan, China, Kenya, Africa, Thailand, and Latin America. Their presence in water resources poses significant environmental and health risks, including fluorosis and arsenicosis. To address this issue, this study developed an integrated process combining biosorbents and ultrafiltration (UF) for the removal of F⁻, As, and turbidity from contaminated water. Laboratory-scale adsorption experiments were conducted using low-cost biosorbents with different biosorbent dosages, specifically Moringa oleifera seed powder (MSP) and sorghum bicolor husk (SBH), along with sand as a binding medium. F⁻ and As concentrations ranging from 2 to 10 mg/L and 3 to 12 mg/L, respectively, were investigated. Biosorbents and their different combinations were tested to determine their efficacy in removing dissolved F⁻ and As. The results showed that a blend of 10-g/L MSP with SBH achieved the highest F⁻ (97.20%) and As (78.63%) removal efficiencies. Subsequent treatment with a UF membrane effectively reduced turbidity and colloidal impurities in the treated water, achieving a maximum turbidity removal efficiency of 95.40%. Equilibrium kinetic and isotherm models were employed to analyze the experimental data, demonstrating good fit. Preliminary cost analysis indicated that the hybrid technology is economically viable and suitable for the separation of hazardous contaminants from aqueous solutions. This study underscores the potential of inexpensive biosorption technologies in providing clean and safe drinking water, particularly in industrial, rural, and urban areas.