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

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...

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Bibliographic Details
Published in:The Science of the total environment 2020-04, Vol.714, p.136721, Article 136721
Main Authors: Gao, Jia, Zhao, Tuokun, Tsang, Daniel C.W., Zhao, Nan, Wei, Hang, Feng, Mingyu, Liu, Kunyuan, Zhang, Weihua, Qiu, Rongliang
Format: Article
Language:English
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Summary: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. [Display omitted] •SB-2324 presented 132% more BET surface area than SB-1438.•SB-1901 provided 215% of Langmuir maximum sorption capacity of S-1438.•Lettuces in the Cd solution fixed with SB-1901 had 44% more biomass than SB-1438.•SB-1901 decreased 18.4% more of Cd levels in lettuce leaves than SB-1438.
ISSN:0048-9697
1879-1026
DOI:10.1016/j.scitotenv.2020.136721