Life cycle assessment of adsorbents for fluoride removal from drinking water in East Africa

Various fluoride adsorbents have been studied for removal of excess fluoride from drinking water to meet the World Health Organization (WHO) Guideline value of 1.5 mg/L. Production of these adsorbents emits contaminants that can affect human health and the environment, but the extent of these impacts is currently unknown. This study evaluates the environmental impacts of four low-cost and easy to use adsorbents: activated alumina, aluminum oxide amended wood char, bone char, and treated alum waste. The environmental impacts of these adsorbents were evaluated using life cycle assessment (LCA). The life cycle stages considered were raw material acquisition, adsorbent manufacturing, and waste management. The functional unit was defined as the quantity of adsorbent necessary to reduce the fluoride concentration of 100,000 L of water from 10 mg/L to the World Health Organization recommended drinking water level of 1.5 mg/L. Eco-indicator and the Tool for Reduction and Assessment of Chemicals and other Environmental Impacts (TRACI) were used to interpret the environmental impacts. The results indicate that the environmental impacts of these adsorbents vary greatly using a common functional unit of treating 100,000 L (100 m3) of fluoride-impacted water. A key determining factor for the impacts is the fluoride adsorption capacity of the adsorbent material because this affects how much material is required to produce safe water. Aluminum oxide amended wood char had the highest overall negative environmental impact in all impact categories, and the lowest adsorption capacity. The two adsorbents that performed the best (lowest environmental impact) were the bone char and the treated alum waste. The environmental impacts of the adsorbents can be reduced by increasing their fluoride adsorption capacity and/or carefully selecting key process components, such as the distance and means of transportation, particularly for activated alumina. Regeneration and reuse of spent adsorbents has the potential to minimize impacts to ecosystem quality.