Column Experiments to Assess the Effects of Electron Donors on the Efficiency of in situ Precipitation of Zn, Cd, Co and Ni in Contaminated Groundwater Applying the Biological Sulfate Removal Technology

Abstract

Background, Aims and Scope. In a previous study, we explored the use of acetate, lactate, molasses, Hydrogen Release Compound (HRCÒ, which is based on a biodegradable poly-lactate ester), methanol and ethanol as carbon source and electron donor to promote bacterial sulfate reduction in batch experiments, this with regards to applying an in situ metal precipitation (ISMP) process as a remediation tool to treat heavy metal contaminated groundwater at the site of a nonferrous metal work company. Based on the results of these batch tests, column experiments were conducted with lactate, molasses and HRCÒ as the next step in our preliminary study for a go-no go decision for dimensioning an on site application of the ISMP process that applies the activity of the endogenous population of sulfate-reducing bacteria (SRB). Special attention was given to the sustainability of the metal precipitation process under circumstances of changing chemical oxygen demand (COD) to [SO42–] ratios or disrupted substrate supply....