Remediation of Heavy Metal-Contaminated Soils Using Phosphate-Enriched Sewage Sludge Biochar

Protogene Mbasabire, Yves Theoneste Murindangabo (), Jakub Brom, Protegene Byukusenge, Jean de Dieu Marcel Ufitikirezi, Josine Uwihanganye, Sandra Nicole Umurungi, Marie Grace Ntezimana, Karim Karimunda and Roger Bwimba
Additional contact information
Protogene Mbasabire: Faculty of Agriculture and Technology, University of South Bohemia in České Budějovice, Studentska 1668, 370 05 České Budějovice, Czech Republic
Yves Theoneste Murindangabo: Institute of Soil Biology and Biogeochemistry, Biology Centre of the Czech Academy of Sciences, Na Sádkách 7, 370 05 České Budějovice, Czech Republic
Jakub Brom: Faculty of Agriculture and Technology, University of South Bohemia in České Budějovice, Studentska 1668, 370 05 České Budějovice, Czech Republic
Protegene Byukusenge: Faculty of Agriculture and Technology, University of South Bohemia in České Budějovice, Studentska 1668, 370 05 České Budějovice, Czech Republic
Jean de Dieu Marcel Ufitikirezi: Faculty of Agriculture and Technology, University of South Bohemia in České Budějovice, Studentska 1668, 370 05 České Budějovice, Czech Republic
Josine Uwihanganye: Faculty of Agriculture and Technology, University of South Bohemia in České Budějovice, Studentska 1668, 370 05 České Budějovice, Czech Republic
Sandra Nicole Umurungi: Faculty of Agriculture and Technology, University of South Bohemia in České Budějovice, Studentska 1668, 370 05 České Budějovice, Czech Republic
Marie Grace Ntezimana: Faculty of Agriculture and Technology, University of South Bohemia in České Budějovice, Studentska 1668, 370 05 České Budějovice, Czech Republic
Karim Karimunda: Faculty of Agriculture and Technology, University of South Bohemia in České Budějovice, Studentska 1668, 370 05 České Budějovice, Czech Republic
Roger Bwimba: Faculty of Agriculture and Technology, University of South Bohemia in České Budějovice, Studentska 1668, 370 05 České Budějovice, Czech Republic

Sustainability, 2025, vol. 17, issue 16, 1-21

Abstract: Heavy metals represent long-lasting contaminants that pose significant risks to both human health and ecosystem integrity. Originating from both natural and anthropogenic activities, they bioaccumulate in organisms through the food web, leading to widespread and long-lasting contamination. Industrialization, agriculture, and urbanization have exacerbated soil and water contamination through activities such as mining, industrial production, and wastewater use. In response to this challenge, biochar produced from waste materials such as sewage sludge has emerged as a promising remediation strategy, offering a cost-effective and sustainable means to immobilize heavy metals and reduce their bioavailability in contaminated environments. Here we explore the potential of phosphate-enriched biochar, derived from sewage sludge, to adsorb and stabilize heavy metals in polluted soils. Sewage sludge was pyrolyzed at various temperatures to produce biochar. A soil incubation experiment was conducted by adding phosphate-amended biochar to contaminated soil and maintaining it for one month. Heavy metals were extracted using a CaCl 2 extraction method and analyzed using atomic absorption spectrophotometry. Results demonstrated that phosphate amendment significantly enhanced the biochar’s capacity to immobilize heavy metals. Amending soils with 2.5 wt% phosphate-enriched sewage sludge biochar led to reductions in bioavailable Cd (by 65–82%), Zn (40–75%), and Pb (52–88%) across varying pyrolysis temperatures. Specifically, phosphate-amended biochar reduced the mobility of Cd and Zn more effectively than unamended biochar, with a significant decrease in their concentrations in soil extracts. For Cu and Pb, the effectiveness varied with pyrolysis temperature and phosphate amendment, highlighting the importance of optimization for specific metal contaminants. Biochar generated from elevated pyrolysis temperatures (500 °C) showed an increase in ash content and pH, which improved their ability to retain heavy metals and limit their mobility. These findings suggest that phosphate-amended biochar reduces heavy metal bioavailability, minimizing their entry into the food chain. This supports a sustainable approach for managing hazardous waste and remediating contaminated soils, safeguarding ecosystem health, and mitigating public health risks.

Keywords: sewage sludge; phosphorus-amended biochar; heavy metal remediation; sustainable waste management; ecosystem health (search for similar items in EconPapers)
JEL-codes: O13 Q Q0 Q2 Q3 Q5 Q56 (search for similar items in EconPapers)
Date: 2025
References: Add references at CitEc
Citations:

Downloads: (external link)
https://www.mdpi.com/2071-1050/17/16/7345/pdf (application/pdf)
https://www.mdpi.com/2071-1050/17/16/7345/ (text/html)

Related works:
This item may be available elsewhere in EconPapers: Search for items with the same title.

Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text

Persistent link: https://EconPapers.repec.org/RePEc:gam:jsusta:v:17:y:2025:i:16:p:7345-:d:1724270

Access Statistics for this article

Sustainability is currently edited by Ms. Alexandra Wu

More articles in Sustainability from MDPI
Bibliographic data for series maintained by MDPI Indexing Manager ().