Effects of Zn in sludge-derived biochar on Cd immobilization and biological uptake by lettuce

Jia Gao, Tuokun Zhao, Daniel C.W. Tsang, Nan Zhao, Hang Wei, Mingyu Feng, Kunyuan Liu, Weihua Zhang, Rongliang Qiu

Research output: Journal article publicationJournal articleAcademic researchpeer-review

21 Citations (Scopus)


Considering the high Zn content of municipal sewage sludge and its competition with Cd during plant uptake due to their similar properties, the presence of Zn in sludge-derived biochar (SDBC) may affect Cd immobilization and uptake by plants. To confirm this, SDBC samples with different Zn contents were prepared and characterized. Their Cd immobilization behavior was studied by conducting batch sorption experiments, and their effects on Cd uptake by lettuce were explored by conducting hydroponic experiments. The results reveal that some Zn contained in the sewage sludge was transformed into ZnO during pyrolysis. The Brunauer-Emmett-Teller (BET) surface area of the SDBC samples containing 2324 mg kg 1 Zn (BC-2324) was 18.3 m2 g−1, which was 132% larger than that of the samples containing 1438 mg kg 1 Zn (BC-1438). The SDBC samples containing 1901 mg kg 1 (BC-1901) exhibited the highest Langmuir sorption capacity of 3476 mg kg 1, which is 115% higher than that of SB-1438. Furthermore, the lettuce remedied with SB-1901 exhibited 44% more biomass; lower peroxidase, catalase, and malondialdehyde activity; and 18.4% less Cd in the leaves of the lettuce than the lettuce remedied with BC-1438, suggesting the potential benefits of using Zn-rich SDBC for soil amendment.

Original languageEnglish
Article number136721
JournalScience of the Total Environment
Publication statusPublished - 20 Apr 2020


  • Cd uptake by lettuce
  • Farmland soil amendment
  • Metal immobilization
  • Potentially toxic elements
  • Sludge-derived biochar
  • Sustainable remediation

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution


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