Land application of sewage sludge biochar: Assessments of soil-plant-human health risks from potentially toxic metals

Jin Zhang; Hanyu Hu; Minyan Wang; Yanan Li; Shengchun Wu; Yucheng Cao; Peng Liang; Jianyun Zhang; Ravi Naidu; Yanju Liu; Yu Bon Man; Ming Hung Wong; Changai Zhang; Shengdao Shan

doi:10.1016/j.scitotenv.2020.144137

Land application of sewage sludge biochar: Assessments of soil-plant-human health risks from potentially toxic metals

Sci Total Environ. 2021 Feb 20:756:144137. doi: 10.1016/j.scitotenv.2020.144137. Epub 2020 Nov 27.

Authors

Jin Zhang¹, Hanyu Hu², Minyan Wang³, Yanan Li², Shengchun Wu², Yucheng Cao², Peng Liang⁴, Jianyun Zhang⁵, Ravi Naidu⁶, Yanju Liu⁶, Yu Bon Man⁷, Ming Hung Wong⁸, Changai Zhang⁹, Shengdao Shan⁵

Affiliations

¹ Zhejiang Province Key Laboratory of Recycling and Eco-Treatment of Waste Biomass, School of Environment and Natural Resources, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310023, China; School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou, Zhejiang 311300, China; Global Centre for Environmental Remediation (GCER), Faculty of Science, The University of Newcastle, Callaghan, NSW 2308, Australia.
² School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou, Zhejiang 311300, China.
³ Jiyang College, Zhejiang A&F University, Zhuji, Zhejiang 311800, China; Global Centre for Environmental Remediation (GCER), Faculty of Science, The University of Newcastle, Callaghan, NSW 2308, Australia.
⁴ School of Environmental and Resource Sciences, Zhejiang A&F University, Hangzhou, Zhejiang 311300, China. Electronic address: liangpeng@zafu.edu.cn.
⁵ Zhejiang Province Key Laboratory of Recycling and Eco-Treatment of Waste Biomass, School of Environment and Natural Resources, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310023, China.
⁶ Global Centre for Environmental Remediation (GCER), Faculty of Science, The University of Newcastle, Callaghan, NSW 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC CARE), The University of Newcastle, Callaghan, NSW 2308, Australia.
⁷ Consortium on Health, Environment, Education and Research (CHEER), Department of Science and Environmental Studies, The Education University of Hong Kong, Tai Po, Hong Kong, China.
⁸ Consortium on Health, Environment, Education and Research (CHEER), Department of Science and Environmental Studies, The Education University of Hong Kong, Tai Po, Hong Kong, China; Zhejiang Province Key Laboratory of Recycling and Eco-Treatment of Waste Biomass, School of Environment and Natural Resources, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310023, China.
⁹ Zhejiang Province Key Laboratory of Recycling and Eco-Treatment of Waste Biomass, School of Environment and Natural Resources, Zhejiang University of Science and Technology, Hangzhou, Zhejiang 310023, China. Electronic address: zca2006@sina.com.

PMID: 33293094
DOI: 10.1016/j.scitotenv.2020.144137

Abstract

Effects of sewage sludge-derived biochar and its precursor on the accumulation of metals (Cd, Cu, Pb and Zn) in soil and their uptake by plants in a 1-year field experiment involving corn-radish rotation were comparatively studied. The human health risks were assessed, and the safe application period of biochar were estimated. The application of biochar, compares to sewage sludge, significantly enhanced the radish yield (p < 0.05; not corn yield) and significantly reduced the accumulation of metals in both plants (p < 0.05), especially the annual application at ≤15 t ha^-1. The hazard quotient analyses of the metals showed there were no health risks to humans (Hazard Index < 1) in consuming the edible parts of the both plants. The application of sewage sludge at ≥15 t ha^-1 resulted in Cd in radish exceeded the threshold for foodstuffs set by China (0.1 mg kg^-1). The total contents of Cd, Cu, Pb and Zn in soil increased gradually as the application of sewage sludge or its biochar increased from 7.5 t ha^-1 to 30 t ha^-1. More metals were found to be introduced to soil by the land application of biochar than by its precursor at the same doses, because the metals were concentrated in biochar during the preparation process. The contamination risk assessment of soil based on the geo-accumulation index, the contamination factor and the pollution load index suggested the application of biochar on farmland should <15 t ha^-1. Therefore, taking into account the yield of and metal concentrations in the radish and corn plants and the contamination risks in soil, it is recommended that the continuous safe application period at an application of 7.5 t ha^-1 year^-1 of biochar should not exceed 15 years, and that of its precursor sewage sludge should not exceed 17 years.

Keywords: Biochar; Land application; Metals; Risks; Sewage sludge.

MeSH terms

Charcoal
China
Humans
Metals, Heavy* / analysis
Sewage
Soil
Soil Pollutants* / analysis

Substances

Metals, Heavy
Sewage
Soil
Soil Pollutants
biochar
Charcoal