A liquid fertilizer obtained through food-waste composting can be used for the preparation of a dissolved
organic carbon (DOC) solution. In this study, we used the DOC solutions for the remediation of a Zncontaminated
soil(with Zn concentrations up to 992 and 757 mg kg−1 in topsoil and subsoil, respectively).
We then determined the factors that affect Zn removal, such as pH, initial concentration of DOC solution,
and washing frequency. Measurements using a Fourier Transform infrared spectrometer (FT-IR) revealed
that carboxyl and amide were the major functional groups in the DOC solution obtained from the liquid
fertilizer. Two soil washes using 1,500 mg L−1 DOC solution with a of pH 2.0 at 25 ◦C removed about 43%
and 21% of the initial Zn from the topsoil and subsoil, respectively. Following this treatment, the pH of
the soil declined from 5.4 to 4.1; organic matter content slightly increased from 6.2 to 6.5%; available
ammonium (NH4
+-N) content increased to 2.4 times the original level; and in the topsoil, the available
phosphorus content and the exchangeable potassium content increased by 1.65 and 2.53 times their
initial levels, respectively.