Remediating Naturally Occurring Radioactive Materials and Other Contaminants in Groundwater Using Locally Prepared Activated Charcoal

Most rural and peri-urban inhabitants in Ghana obtain their drinking water primarily from groundwater. However, groundwater quality is threatened by the presence of pollutants, including toxic metals, naturally occurring radioactive materials, hydrocarbons, trace organic contaminants, pesticides, nanoparticles, microplastics, and other emerging contaminants, posing risks to human health, ecological systems, and sustainable socioeconomic development.

This study evaluated groundwater quality using chemical and radiological analyses. In addition, a locally produced material (activated charcoal) was developed and tested for the removal of chemical and radiological contaminants from groundwater.

Groundwater in Teiman, Ghana, showed Rn-222 concentrations ranging from 1 to 35 Bq L⁻¹ (mean: 8.4 ± 6.1 Bq L⁻¹), with 19% of samples exceeding the USEPA limit of 11 Bq L⁻¹. Activated charcoal reduced Rn-222 concentrations by 71–98% (mean: 89 ± 8%). The mean pre-treatment ingestion and inhalation doses were 21.5 µSv yr⁻¹ and 17 µSv yr⁻¹, respectively, and were reduced after treatment. Other NORMs included Ra-226 (0.08–0.81 Bq L⁻¹), Ra-228 (0.05–0.62 Bq L⁻¹), and Th-232 (0.03–0.58 Bq L⁻¹). Annual effective doses ranged from 0.06 to 0.26 µSv yr⁻¹ (ingestion) and from 0.26 to 1.15 µSv yr⁻¹ (inhalation), which were below the WHO guideline value of 0.1 mSv yr⁻¹ but still warrant reduction. Locally prepared CaCl₂-activated charcoal derived from coconut husk reduced Ra-226 and Ra-228 by 71 ± 9%, Th-232 by 58 ± 11%, EC and TDS by approximately 42%, and cation and anion concentrations by 54–92%. The pH increased from 6.2 ± 0.4 to 7.5 ± 0.3, which falls within the WHO recommended range of 6.5–8.5.

The results showed varying percentage reductions in the physicochemical parameters and radionuclide activity concentrations studied. Activated charcoal prepared from coconut husk demonstrated significant potential for removing chemical and radiological contaminants from groundwater.

Activated charcoal prepared from coconut husk demonstrated significant potential for removing chemical and radiological contaminants from groundwater. The low-cost filter is scalable for use in rural communities.