Copper Complexation of Humic Substances Generated in a Landfill Site that is Mainly for Municipal Solid Waste Incineration Residue Disposal

Abstract

Humic substances are known to have great impact on heavy metal mobility in aquatic environments. Therefore, the complexation of humic substances, which was generated in landfilled municipal solid waste incineration (MSWI) residues, with heavy metals were investigated to evaluate their impact on heavy metal mobility in a landfill body. This study focused on copper complexation with landfill humic substances. Humic substances were extracted from 13-year-old landfilled MSWI residues. They were used for copper complexation experiments with initial copper concentrations ranging from 1.0 × 10^-8 mol-Cu/L to 1.0 × 10^-6 mol-Cu/L; humic/fulvic acid concentration of 47.61 mg-C/L; pH range from 6 to 8; and 24-hour contact time. 59.5% to 99.9% of spiked copper was bounded with humic substances at pH 6 to 8. This series of experiments suggested significant impact of humic substance complex on copper mobility in a landfill body. Humic acid had several orders of magnitude larger complexation capacity for copper than that of fulvic acid. Although copper complexation capacities of landfill humic/fulvic acid were much lower than those of generic humic/fulvic acid, landfill fulvic acid had comparable capacity with incubated fulvic acid. This implies similar characteristics of fulvic acid generated in MSWI residues regardless of the humification environment.