Heavy Metal Levels in Surface Water of Djongo Gold District, East Cameroon, and Treatment with Activated Carbon

The scavenging of gold in East Cameroon has continuously loaded the environment with heavy metallic elements (mercury, lead, copper, nickel, and zinc). Heavy metal release through the use of chemicals for artisanal gold recovery can be challenging for humans and aquatic ecosystems in the Djongo region. Thus, there is an increasing need to remove heavy metals from wastewater to limit its detrimental effects. The current scenario of heavy metal contamination in water from artisanal gold mining sites in the Djongo gold district was investigated. Ten water samples were collected during the wet season (July) from selected areas in Djongo, where mining activities are ongoing. Physicochemical parameters, such as pH, electrical conductivity, total dissolved solids, and heavy metal ions (mercury, lead, nickel, copper, and zinc) were determined in the water samples. The results revealed high concentrations of mercury (90 mg/L) and lead (71.208 mg/L), whereas copper, zinc, and nickel concentrations were below the WHO acceptable limits. However, the bioaccumulation of these heavy metals is dangerous for human exposure. The adsorption process was applied as a treatment method that involved the removal of heavy metals from wastewater using activated carbon as the absorbent. This mitigation measure met the expected outcome, as the heavy metal concentrations were drastically reduced after treatment. Nickel, zinc, copper, lead, and mercury were reduced by 84%, zinc (77%), copper (71%), lead (69.6%) and Mercury (62.6%). This study demonstrates a vital approach for mitigating the release of heavy metals in water during mining activities using activated carbon.