Screening of variable importance for optimizing electrodialytic remediation of heavy metals from polluted harbour sediments

摘要

Using multivariate design and modelling, optimal conditions forelectrodialytic remediation (EDR) of heavy metals were determined forpolluted harbour sediments from Hammerfest harbour located in thegeographic Arctic region of Norway. The comparative importance of thevariables; current density, remediation time, light/no light, the liquid-solidratio and stirring rate of the sediment suspension were determined in 15laboratory scale EDR experiments by projection to latent structures (PLS).The relation between the X matrix (experimental variables) and the Ymatrix (removal efficiencies) was computed and variable importance inthe projection was used to assess the influence of the experimentalvariables. Current density and remediation time proved to have the highestinfluence on the remediation of the heavy metals Cr, Cu, Ni, Pb and Zn inthe studied experimental domain. In addition it was shown that excludingthe acidification time improved the PLS model, indicating the importanceof applying a limited experimental domain that covers the removal phasesof each heavy metal in the specific sediment. Based on PLS modelling theoptimal conditions for remediating the Hammerfest sediment wasdetermined; operating in the experimental domain of 0.5-0.8 mA/cm2 anda remediation time after acidification of 450-570 hours met acceptablelevels according to Norwegian sediment quality guidelines