Phytotoxicity of sewage sludge passivated by modified potassium feldspar and its effect on ryegrass growth

ABSTRACT

Effective passivation of heavy metals in sludge is the key to achieve its land use. Potassium feldspar was modified to obtain G×K900, with a lower crystallinity, a higher specific surface area and cationic exchange capacity. G×K900 was chosen to passivate heavy metals in the sludge, and the best passivation conditions were 30% addition and a 10-day passivation period. The passivated sludge extract had no adverse effects on ryegrass germination and promoted radicle growth. The pot experiment revealed that adding 10% passivated sludge encouraged ryegrass growth while having no appreciable impact on the contents of Cu, Cr, Zn and Pb in the roots and above-ground parts compared to control treatment. The transfer factors of the four metals were all less than 1. Passivated sludge was used as a growing medium for landscaping plants, which provided a theoretical foundation for sludge land use and a resource outlet for potassium feldspar minerals.

KEYWORDS:

• Sewage sludge
• heavy metals
• passivation
• phytotoxicity
• potassium feldspar

Acknowledgments

This work was supported by the Natural Science Foundation of Shandong Province, China (ZR2020MB141) and the National-level and School-level Student Innovation and Entrepreneurship Training Program (202110431011).

Data availability

The datasets supporting the relevant research findings in this article are available from the email of the corresponding author ([email protected]) through reasonable request.

Disclosure statement

The authors report there are no competing interests to declare.References

Additional information

Funding

The work was supported by the Natural Science Foundation of Shandong Province [ZR2020MB141]; National-level and School-level Student Innovation and Entrepreneurship Training Program [202110431011].