Removal of fluoride, arsenic and coliform bacteria by modified homemade filter media from drinking water

Abstract

This study developed a novel self-made composite filter media by improving the traditional slow sand filtration process, and systematically evaluated its simultaneous removal efficiency of fluoride, arsenic, and total coliform bacteria in drinking water. Using batch experiments, the influence of treatment duration (2–12 h) on pollutant removal efficiency was investigated. Physicochemical and microbiological analyses of pre- and post-filtration water samples were conducted according to standard methods. Experimental results indicate that at the optimal treatment time of 10 hours, removal rates for fluoride, arsenic, and total coliform bacteria reached 85.60%, 93.07%, and 100%, respectively. with residual concentrations of 0.72 mg/L, 0.009 mg/L, and 0 CFU/100 mL, respectively, all meeting the World Health Organization (WHO) drinking water safety standards. This modified homemade filter media process features low cost, simple operation, and high removal efficiency, making it suitable for promotion and application in resource-limited rural and remote areas.

Introduction
Waterborne diseases account for approximately 80% of global infectious illnesses. Ensuring safe drinking water and reducing disease burden necessitates effective removal of pathogenic microorganisms, suspended solids, organic pollutants, and harmful inorganic chemicals from water sources. Among numerous water contaminants, fluoride, arsenic, and total coliform bacteria warrant particular attention due to their widespread health hazards. While adequate fluoride (approximately 1 mg/L) prevents dental caries, long-term excessive intake causes diseases like dental fluorosis and skeletal fluorosis. Arsenic exposure correlates with acute and chronic poisoning symptoms, including skin lesions and visceral carcinogenesis. Total coliform bacteria, as indicator microorganisms of fecal contamination, often accompany pathogenic risks and can cause digestive diseases like diarrhea and vomiting.

Current removal technologies for fluoride, arsenic, and microorganisms primarily include coagulation-sedimentation, adsorption, membrane separation, and ion exchange. However, most of these methods are costly and operationally complex, making them difficult to implement in rural areas of developing countries. Therefore, developing economically viable and easily maintainable decentralized water treatment technologies holds significant practical importance.

In recent years, researchers have focused on exploring low-cost adsorption filtration technologies based on natural materials (such as clay minerals, coal by-products, and plant materials), building upon traditional processes like slow sand filtration and diatomaceous earth filtration. However, traditional slow sand filtration exhibits limited removal capacity for dissolved inorganic pollutants like fluoride, making it difficult to fully meet water quality safety requirements.

To address this, this study modifies and optimizes traditional homemade slow sand filter media to enhance its synergistic removal efficiency for fluoride, arsenic, and microorganisms. Optimal operating parameters are experimentally determined to provide a feasible small-scale drinking water purification solution for rural areas.

Reference:https://www.culligan.com/blog/how-to-remove-fluoride-from-water