Environmental Challenges (Dec 2021)
Stabilization of heavy metals in soil and leachate at Dompoase landfill site in Ghana
Abstract
The levels of heavy metals pollution in water and soil around landfill sites are increasing due to the indiscriminate dumping of domestic and industrial wastes at these sites. This research was conducted to study the characterisation and stabilisation of heavy metals in soils and leachate at the Dompoase landfill site, Kumasi-Ghana. Nine surface composite soil samples (< 40 cm deep) were collected at Dompoase landfill site from the middle (hotspot) of the landfill site through a 15 m radius away from the landfill cell where there were no dumping activities. Untreated leachate sample was also collected from a dugout around the landfill cell at a 4 m distance. This untreated leachate sample is estimated to be over 10 years and has a pH of 7.5. Physicochemical properties (i.e., electrical conductivity, pH, temperature, moisture and clay contents) and heavy metals (i.e., Cu, Cd, Fe, Ni and Zn) analyses were conducted on the collected samples. The results showed that the mean concentrations of all the heavy metals in soil studied were all above the Ghana Environmental Protection Agency (EPA) and WHO guidelines with the exception of Ni. All the psychochemical parameters were also within the EPA guidelines. Concentrations of Ni and Cd in the leachate sample were low and could not be detected. Cu and Zn recorded concentrations below the EPA and WHO guidelines while Fe recorded concentrations above the EPA and WHO limits. The contamination factor revealed that Cu (CF = 0.00) can be classified as exhibiting low contamination with Fe (CF = 1.50), Cd (CF = 1.80) and Zn (CF = 2.35) showing moderate contaminations. Low-grade CaO in varying quantities was utilised as stabilising agent to stabilise the heavy metals within various samples for a 21-day period. The physicochemical properties were monitored within the 21-day period during the heavy metal stabilisation. The results showed a percentage reduction in concentrations of metals within the period. The work shows that low-grade CaO can effectively be used in the remediation of contaminated sites as a result of anthropogenic activities.
