Effect of cleanup of spiked sludge on corn growth biosorption and leaching of metals

Abstract

A chemical leaching process has been used for the cleanup of two municipal biosolids (MOS and BES) spiked with Cd, Cu, Zn or their mixture prior to agricultural use. Non-cleaned, cleaned and washed biosolids were compared as soil amendments for corn cultivation inside glasshouse. Corn growth, biosorption of metals and leaching of these metals in leachate were measured. Results showed that biosolid amendments tend to produce more aerial biomass. Cleanup and washing of BES biosolid significantly augmented total biomass of roots and stalks, respectively. Regarding biosorption of metals, Cd could not be found neither in corn seeds, nor in stalks, while slight amounts of Cu were detected. Whereas Cd and Cu diminished in the order roots > leaves > stalks, Zn diminished from leaves > roots > stalks. Cleanup and washing of MOS and BES biosolids significantly lowered biosorption of Cd, Cu, Zn, and other metals. Leaching into the outlet water varied with time, but average concentrations were moderately low. There were significant amounts of metal leached from MOS biosolid. The effects of cleanup and washing of both biosolids on biosorption and leaching depended on the initial metallic charge and the biosolid type.