1 research outputs found
Effective Remediation of Groundwater Fluoride with Inexpensively Processed Indian Bauxite
India
represents one-third of the world’s fluorosis burden
and is the fifth global producer of bauxite ore, which has previously
been identified as a potential resource for remediating fluoride-contaminated
groundwater in impoverished communities. Here, we use thermal activation
and/or groundwater acidification to enhance fluoride adsorption by
Indian bauxite obtained from Visakhapatnam, an area proximate to endemic
fluorosis regions. We compare combinatorial water treatment and bauxite-processing
scenarios through batch adsorption experiments, material characterization,
and detailed cost analyses. Heating Indian bauxite above 300 °C
increases available surface area by > 15× (to ∼170
m<sup>2</sup>/g) through gibbsite dehydroxylation and reduces the
bauxite
dose for remediating 10 ppm F<sup>–</sup> to 1.5 ppm F<sup>–</sup> by ∼93% (to 21 g/L). Additionally, lowering
groundwater pH to 6.0 with HCl or CO<sub>2</sub> further reduces the
average required bauxite doses by 43–73% for ores heated at
300 °C (∼12 g/L) and 100 °C (∼77 g/L). Product
water in most examined treatment scenarios complies with EPA standards
for drinking water (e.g., As, Cd, Pb, etc.) but potential leaching
of Al, Mn, and Cr is of concern in some scenarios. Among the defluoridation
options explored here, bauxite heated at 300 °C in acidified
groundwater has the lowest direct costs ($6.86 per person per year)
and material-intensity