Comparative characterization of sewage sludge compost and soil: Heavy metal leaching characteristics

•We comparatively characterized sewage sludge compost (SSC) and soil.•SSC and soil had different properties, but similar processes controlled leaching.•Screening indicated a higher leaching of metals in SSC due to its greater DOC content.•SSC application increased the leaching of heavy metals due to the increase of DOM.•The addition of SSC at 4% did not change the heavy metal speciation in the soil. The leaching and accumulation of heavy metals are major concerns following the land application of sewage sludge compost (SSC). We comparatively characterized SSC, the reference soil, and the SSC amended soil to investigate their similarities and differences regarding heavy metal leaching behavior and then to evaluate the effect of SSC land application on the leaching behavior of soil. Results showed that organic matter, including both of particulate organic matter (POM) and dissolved organic matter (DOM), were critical factors influencing heavy metal leaching from both of SSC and the soil. When SSC was applied to soil at the application rate of 48t/ha, the increase of DOM content slightly enhanced heavy metal leaching from the amended soil over the applicable pH domain (6