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Source-dependent pyrolysis temperature optimization for sewage sludge biochar: balancing nutrient retention and heavy metal passivation.

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Title: Source-dependent pyrolysis temperature optimization for sewage sludge biochar: balancing nutrient retention and heavy metal passivation.
Authors: Chu Z; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China., Shu L; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China., Liu Y; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China., Jiang P; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China., Wang C; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China., Li S; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China., Liu X; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China., Gong H; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China., Yang Z; College of Resources and Environment, Key Laboratory of Agricultural Environment in Universities of Shandong, Shandong Agricultural University, Tai'an 271000, China. Electronic address: zkyang@sdau.edu.cn.
Source: Waste management (New York, N.Y.) [Waste Manag] 2026 Sep 30; Vol. 225, pp. 115785. Date of Electronic Publication: 2026 Aug 03.
Publication Type: Journal Article
Language: English
Journal Info: Publisher: Pergamon Press Country of Publication: United States NLM ID: 9884362 Publication Model: Print-Electronic Cited Medium: Internet ISSN: 1879-2456 (Electronic) Linking ISSN: 0956053X NLM ISO Abbreviation: Waste Manag Subsets: MEDLINE
Imprint Name(s): Original Publication: New York : Pergamon Press, c1989-
MeSH Terms: Sewage*/chemistry , Sewage*/analysis , Metals, Heavy*/analysis , Metals, Heavy*/chemistry , Charcoal*/chemistry , Charcoal*/analysis , Pyrolysis*, Nutrients/analysis ; Nitrogen/analysis ; Fertilizers/analysis ; Temperature
Abstract: Addressing the conflict between rising sludge production and its resource utilization, this study evaluated environmental risks and resource potential of sludge-derived biochar. The nutrients and heavy metals in sludge and biochar were systematically analyzed based on mixed industrial-domestic sludge and purely domestic sludge, produced at pyrolysis temperatures from 350°C to 800°C. Results indicated that sludge source critically determined its resource utilization pathway. For mixed sludge, pyrolysis at 550-650°C concentrated total nutrients by 77-82% (peaking at 13-14.5%), whereas domestic sludge retained available nitrogen best at < 450°C, limiting nitrogen loss to < 50%. Pyrolysis reduced environmental risks by stabilizing heavy metals. For mixed sludge at 650°C, residual fractions of Cu, Cr, and Pb exceeded 80%, reducing potential ecological risks (RI) to mild pollution levels (38.98 and 21.14). For domestic sludge at 450°C, Cd and Zn leaching toxicity was effectively passivated to below 0.001 mg/kg and 2 mg/kg, respectively, meeting safety standards. This study confirms that a temperature-based strategy based on source differentiation can simultaneously optimize the nutrient efficiency and environmental safety of sludge-derived biochar, providing important insights and theoretical framework for fertilizer use in future studies.
(Copyright © 2026 Elsevier Ltd. All rights reserved.)
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Contributed Indexing: Keywords: Ecological risk; Heavy metal passivation; Nutrient recovery; Pyrolysis temperature; Resource utilization; Sludge biochar
Substance Nomenclature: 0 (Sewage)
0 (biochar)
0 (Metals, Heavy)
16291-96-6 (Charcoal)
N762921K75 (Nitrogen)
0 (Fertilizers)
Entry Date(s): Date Created: 20260803 Date Completed: 20260817 Latest Revision: 20260817
Update Code: 20260818
DOI: 10.1016/j.wasman.2026.115785
PMID: 42546454
Database: MEDLINE
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  Data: Source-dependent pyrolysis temperature optimization for sewage sludge biochar: balancing nutrient retention and heavy metal passivation.
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  Data: &lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Chu+Z%22&quot;&gt;Chu Z&lt;/searchLink&gt;; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Shu+L%22&quot;&gt;Shu L&lt;/searchLink&gt;; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Liu+Y%22&quot;&gt;Liu Y&lt;/searchLink&gt;; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Jiang+P%22&quot;&gt;Jiang P&lt;/searchLink&gt;; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Wang+C%22&quot;&gt;Wang C&lt;/searchLink&gt;; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Li+S%22&quot;&gt;Li S&lt;/searchLink&gt;; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Liu+X%22&quot;&gt;Liu X&lt;/searchLink&gt;; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Gong+H%22&quot;&gt;Gong H&lt;/searchLink&gt;; School of Life and Health Sciences, Environmental Engineering, Hefei Uiversity, Hefei 230000, China.&lt;br /&gt;&lt;searchLink fieldCode=&quot;AU&quot; term=&quot;%22Yang+Z%22&quot;&gt;Yang Z&lt;/searchLink&gt;; College of Resources and Environment, Key Laboratory of Agricultural Environment in Universities of Shandong, Shandong Agricultural University, Tai&#39;an 271000, China. Electronic address: zkyang@sdau.edu.cn.
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  Data: &lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Sewage%22&quot;&gt;Sewage*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Sewage+chemistry%22&quot;&gt;chemistry&lt;/searchLink&gt; &lt;br /&gt;&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Sewage%22&quot;&gt;Sewage*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Sewage+analysis%22&quot;&gt;analysis&lt;/searchLink&gt; &lt;br /&gt;&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Metals%2C+Heavy%22&quot;&gt;Metals, Heavy*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Metals%2C+Heavy+analysis%22&quot;&gt;analysis&lt;/searchLink&gt; &lt;br /&gt;&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Metals%2C+Heavy%22&quot;&gt;Metals, Heavy*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Metals%2C+Heavy+chemistry%22&quot;&gt;chemistry&lt;/searchLink&gt; &lt;br /&gt;&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Charcoal%22&quot;&gt;Charcoal*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Charcoal+chemistry%22&quot;&gt;chemistry&lt;/searchLink&gt; &lt;br /&gt;&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Charcoal%22&quot;&gt;Charcoal*&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Charcoal+analysis%22&quot;&gt;analysis&lt;/searchLink&gt; &lt;br /&gt;&lt;searchLink fieldCode=&quot;MM&quot; term=&quot;%22Pyrolysis%22&quot;&gt;Pyrolysis*&lt;/searchLink&gt;&lt;br /&gt;&lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Nutrients%22&quot;&gt;Nutrients&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Nutrients+analysis%22&quot;&gt;analysis&lt;/searchLink&gt; ; &lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Nitrogen%22&quot;&gt;Nitrogen&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Nitrogen+analysis%22&quot;&gt;analysis&lt;/searchLink&gt; ; &lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Fertilizers%22&quot;&gt;Fertilizers&lt;/searchLink&gt;/&lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Fertilizers+analysis%22&quot;&gt;analysis&lt;/searchLink&gt; ; &lt;searchLink fieldCode=&quot;MH&quot; term=&quot;%22Temperature%22&quot;&gt;Temperature&lt;/searchLink&gt;
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Addressing the conflict between rising sludge production and its resource utilization, this study evaluated environmental risks and resource potential of sludge-derived biochar. The nutrients and heavy metals in sludge and biochar were systematically analyzed based on mixed industrial-domestic sludge and purely domestic sludge, produced at pyrolysis temperatures from 350&#176;C to 800&#176;C. Results indicated that sludge source critically determined its resource utilization pathway. For mixed sludge, pyrolysis at 550-650&#176;C concentrated total nutrients by 77-82% (peaking at 13-14.5%), whereas domestic sludge retained available nitrogen best at&#160;&amp;lt;&#160;450&#176;C, limiting nitrogen loss to&#160;&amp;lt;&#160;50%. Pyrolysis reduced environmental risks by stabilizing heavy metals. For mixed sludge at 650&#176;C, residual fractions of Cu, Cr, and Pb exceeded 80%, reducing potential ecological risks (RI) to mild pollution levels (38.98 and 21.14). For domestic sludge at 450&#176;C, Cd and Zn leaching toxicity was effectively passivated to below 0.001&#160;mg/kg and 2&#160;mg/kg, respectively, meeting safety standards. This study confirms that a temperature-based strategy based on source differentiation can simultaneously optimize the nutrient efficiency and environmental safety of sludge-derived biochar, providing important insights and theoretical framework for fertilizer use in future studies.&lt;br /&gt; (Copyright &#169; 2026 Elsevier Ltd. All rights reserved.)
– Name: Abstract
  Label: Competing Interests
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  Data: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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  Data: &lt;i&gt;Keywords: &lt;/i&gt;Ecological risk; Heavy metal passivation; Nutrient recovery; Pyrolysis temperature; Resource utilization; Sludge biochar
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  Data: 0 (Sewage)&lt;br /&gt;0 (biochar)&lt;br /&gt;0 (Metals, Heavy)&lt;br /&gt;16291-96-6 (Charcoal)&lt;br /&gt;N762921K75 (Nitrogen)&lt;br /&gt;0 (Fertilizers)
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        Value: 10.1016/j.wasman.2026.115785
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        Text: English
    PhysicalDescription:
      Pagination:
        StartPage: 115785
    Subjects:
      – SubjectFull: Nutrients analysis
        Type: general
      – SubjectFull: Nitrogen analysis
        Type: general
      – SubjectFull: Fertilizers analysis
        Type: general
      – SubjectFull: Temperature
        Type: general
      – SubjectFull: Sewage chemistry
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      – SubjectFull: Sewage analysis
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        Type: general
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        Type: general
      – SubjectFull: Charcoal chemistry
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      – SubjectFull: Charcoal analysis
        Type: general
      – SubjectFull: Pyrolysis
        Type: general
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      – TitleFull: Source-dependent pyrolysis temperature optimization for sewage sludge biochar: balancing nutrient retention and heavy metal passivation.
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              Text: 2026 Sep 30
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