Co-pyrolysis of sewage sludge and biomass for stabilizing heavy metals and reducing biochar toxicity: A review

Badr A. Mohamed, Roger Ruan, Muhammad Bilal, Nadeem A. Khan, Mukesh Kumar Awasthi, Mariam A. Amer, Lijian Leng, Mohamed A. Hamouda, Dai Viet Nguyen Vo, Jian Li

Research output: Contribution to journalReview articlepeer-review

25 Citations (Scopus)


The huge amounts of sewage sludge produced by municipal wastewater treatment plants induce major environmental and economical issues, calling for advanced disposal methods. Traditional methods for sewage sludge disposal increase greenhouse gas emissions and pollution. Moreover, biochar created from sewage sludge often cannot be used directly in soil applications due to elevated levels of heavy metals and other toxic compounds, which alter soil biota and earthworms. This has limited the application of sewage sludge-derived biochar as a fertilizer. Here, we review biomass and sewage sludge co-pyrolysis with a focus on the stabilization of heavy metals and toxicity reduction of the sludge-derived biochar. We observed that co-pyrolyzing sewage sludge with biomass materials reduced heavy metal concentrations and decreased the environmental risk of sludge-derived biochar by up to 93%. Biochar produced from sewage sludge and biomass co-pyrolysis could enhance the reproduction stimulation of soil biota by 20‒98%. Heavy metals immobilization and transformation are controlled by the co-feed material mixing ratio, pyrolysis temperature, and pyrolysis atmosphere.

Original languageEnglish
Pages (from-to)1231-1250
Number of pages20
JournalEnvironmental Chemistry Letters
Issue number2
Publication statusPublished - Apr 2023


  • Co-pyrolysis
  • Environmental risk assessment
  • Heavy metals
  • Sewage sludge
  • Soil biota
  • Synergistic effects

ASJC Scopus subject areas

  • Environmental Chemistry


Dive into the research topics of 'Co-pyrolysis of sewage sludge and biomass for stabilizing heavy metals and reducing biochar toxicity: A review'. Together they form a unique fingerprint.

Cite this