Developing mass transfer model for predicting concentration profiles of contaminants in groundwater resource

Abstract

This work involves experimental analyses on three abandoned dumpsites (Nkpolu, Oyigbo, and Elekahia) in Port Harcourt to determine the concentrations of lead, cadmium, and Iron in soil and existing tap water close to the dumpsite. Model for the prediction of lead (Pb), cadmium (Cd) and Iron (Fe) migration from abandoned dumpsite into groundwater has been developed. The model was solved and validated with experimental results. Statistical analysis was performed between the experiment and model result to determine the significant difference. The model validation showed goodness fit which was further validated by statistical analysis as there was no significant difference at p<0.05. The simulation performed to determine the quality of existing groundwater obtained from taps close to the abandoned dumpsites showed that the contaminants’ concentration decreased as the depth from point source increased into the groundwater aquifer. At the 60 meters depth, the result obtained from predictive model showed that Pb (0.000182mg/L for Nkpolu, 0.000194mg/L for Oyigbo and 0.000482 mg/L for Elekahia dumpsites, Cd (9.77x10^-6mg/L for Nkpolu and 6.98 x10^-6mg/L for Oyigbo and Elekahia dumpsites and Fe (0.000347mg/L for Nkpolu, 0.00419mg/L for Oyigbo and 0.00415mg/L for Elekahia dumpsites. The concentrations were below the international standard limit for drinking water quality (0.01mg/L for Pb, 0.003mg/L for Cd and 0.3mg/L for Fe). However, the laboratory analysis showed that only water sample collected from Nkpolu abandoned dumpsite met the international standard limit. Results showed that the increase in seepage velocity would impact negatively on the contamination of groundwater.

Keywords: Leachate, adsorption, solid wastes, heavy metals, aqueous solution, pollution.