Synergistic remediation of e-waste contaminated soil using thermally treated sludge residue and Lolium perenne L.

Abstract

Abstract Electronic waste (e-waste) generation has significantly increased because of the widespread use of electronic products, and thermally treated sludge residue improves e-waste-contaminated soil by synergizing with Lolium perenne L. This study investigated the effects of different doses of thermally treated sludge residue (0% and 5%) in synergy with L. perenne L. on organic matter, nutrients, heavy metal morphology, and heavy metal uptake and transport by L. perenne L. in e-waste-contaminated soil using pot experiments. The results showed that the thermally treated sludge residue improved soil quality and significantly increased soil conductivity, cation exchange, organic matter, effective phosphorus, and fast-acting potassium content. New heavy metal crystalline phases were detected, and soil solubility humus components were found. Sludge fermentation residue significantly increased dissolved organic matter content, whereas sludge pyrolysis residue showed no significant effect. The combination of thermally treated sludge residue and L. perenne L. increased steady-state proportions of Cu, Zn, Pb, and Cd. The thermally treated sludge residue promoted L. perenne L. growth, increasing fresh weight, plant height, phosphorus uptake, and potassium uptake of L. perenne L.; it significantly reduced L. perenne L. response to Cu, Zn, Pb, and Cd. In addition, L. perenne L. promoted the activity of microorganisms in thermally treated sludge residue and improved its ability to reduce heavy metals. This approach has the potential for ecological remediation of contaminated sites, providing a new method for the remediation of e-waste-contaminated soil.