Evaluation of the suitability of integrated bone char- and biochar-treated groundwater for drinking using single-factor, Nemerow, and heavy metal pollution indexes

The treatment of contaminated groundwater using integrated bone char and biochar beds has been studied. The bone char and biochar were made in a locally built double-barrel retort utilising cow bones, coconut husks, bamboo, neem trees, and palm kernel shells at 450 °C and were graded into 0.05- and 0.315-mm sizes. Eight groundwater treatment experiments (BF2-BF9) were performed in columns with bed heights of 8.5–16.5 cm to remove nutrients, heavy metals, microorganisms, and interfering ions from groundwater using bone char, biochar, and a combination of bone and biochar. The water samples were analysed for twenty-one water quality parameters including pH, total dissolved solids, conductivity, turbidity, fluoride, chloride, sodium, and potassium. The rest were total coliforms, faecal coliforms, total heterotrophic bacteria, Escherichia coli, manganese, and total iron. The effectiveness of the treatment processes was assessed using the Ghana standard authority and the World Health Organisation’s recommended values for drinking water quality. The results were shared using a simplified single-factor index, Nemerow’s pollution index, and a heavy metal pollution index with decision-makers as a technology for groundwater treatment in rural communities in Africa. Bone char was more effective in removing total heterotrophic bacteria than any of the other treatment agents tested. This is because of its compact nature and small particle size. The quality of water treated by BF3, BF5, BF6, BF7, BF8, and BF9 was fit for drinking based on the single-factor and heavy-metal pollution evaluation because they have the lowest level of pollution. However, Nemerow pollution analysis found only BF5 to be the most suitable for public use.