title: Influence of pyrolysis temperature on properties and environmental safety of heavy metals in biochars derived from municipal sewage sludge.
abstract: Dried raw sludge was pyrolyzed at temperatures ranging from 400 to 600°C at the increase of 50°C intervals to investigate the influence of pyrolysis temperature on properties and environmental safety of heavy metals in biochar derived from municipal sewage sludge. The sludge biochar yield decreased significantly with increasing pyrolysis temperature but the pH, ash content and specific surface area increased. Conversion of sludge to biochar markedly decreased the H/C and N/C ratios. FT-IR analysis confirmed a dramatic depletion of H and N and a higher degree of aromatic condensation in process of biochar formation at higher temperatures. The total concentrations of Cu, Zn, Pb, Cr, Mn, and Ni increased with conversion of sludge to biochar and increasing pyrolysis temperature. However, using BCR sequential extraction and analysis, it was found that most of the heavy metals existed in the oxizable and residual forms after pyrolysis, especially at 600°C, resulting in a significant reduction in their bioavailability, leading to a very low environmental risk of the biochar. The present study indicates pyrolysis is a promising sludge treatment method for heavy metals immobilization in biochar, and highlights the potential to minimize the harmful effects of biochar by controlling pyrolysis temperature.
authors: Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, School of Environmental and Resource Sciences, Zhejiang A & F University, 88 Huancheng North Road, Lin'an, Hangzhou 311300, China.
authors: Junwei
authors: J
authors: Jin
authors: Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, School of Environmental and Resource Sciences, Zhejiang A & F University, 88 Huancheng North Road, Lin'an, Hangzhou 311300, China.
authors: Yanan
authors: Y
authors: Li
authors: Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, School of Environmental and Resource Sciences, Zhejiang A & F University, 88 Huancheng North Road, Lin'an, Hangzhou 311300, China.
authors: Jianyun
authors: J
authors: Zhang
authors: Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, School of Environmental and Resource Sciences, Zhejiang A & F University, 88 Huancheng North Road, Lin'an, Hangzhou 311300, China.
authors: Shengchun
authors: S
authors: Wu
authors: Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, School of Environmental and Resource Sciences, Zhejiang A & F University, 88 Huancheng North Road, Lin'an, Hangzhou 311300, China.
authors: Yucheng
authors: Y
authors: Cao
authors: Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, School of Environmental and Resource Sciences, Zhejiang A & F University, 88 Huancheng North Road, Lin'an, Hangzhou 311300, China.
authors: Peng
authors: P
authors: Liang
authors: Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, School of Environmental and Resource Sciences, Zhejiang A & F University, 88 Huancheng North Road, Lin'an, Hangzhou 311300, China; Consortium on Health, Environment, Education and Research (CHEER), Department of Science and Environmental Studies, The Education University of Hong Kong, 10 Lo Ping Road, Tai Po, Hong Kong, China. Electronic address: jzhang@zafu.edu.cn.
authors: Jin
authors: J
authors: Zhang
authors: Consortium on Health, Environment, Education and Research (CHEER), Department of Science and Environmental Studies, The Education University of Hong Kong, 10 Lo Ping Road, Tai Po, Hong Kong, China.
authors: Ming Hung
authors: MH
authors: Wong
authors: Jiyang College, Zhejiang A & F University, 77 Puyang Road, Zhuji 311800, China. Electronic address: minyanwang@aliyun.com.
authors: Minyan
authors: M
authors: Wang
authors: Institute of Ecological Environment, Zhejiang University of Science & Technology, 318 Liuhe Road, Hangzhou 310023, China.
authors: Shengdao
authors: S
authors: Shan
authors: Key Laboratory of Soil Contamination Bioremediation of Zhejiang Province, School of Environmental and Resource Sciences, Zhejiang A & F University, 88 Huancheng North Road, Lin'an, Hangzhou 311300, China.
authors: Peter
authors: P
authors: Christie
keywords: BCR sequential extraction; Environmental risk assessment; Heavy metals; Sewage sludge biochar; Thermal pyrolysis