Biochar and hydrochar derived from freshwater sludge: Characterization and possible applications

Area of Science:

• Environmental Science
• Materials Science
• Waste Management

Background:

• Freshwater sludge (FS) is a substantial waste product from drinking water treatment.
• Current disposal methods for FS, such as landfilling, are unsustainable.
• There is a need for innovative reuse strategies for FS.

Purpose of the Study:

• To investigate the production of biochar and hydrochar from freshwater sludge.
• To characterize the properties of FS-derived biochar and hydrochar.
• To evaluate the potential applications of these carbonaceous materials.

Main Methods:

• Biochar production via pyrolysis at 300, 500, and 700 °C.
• Hydrochar production via hydrothermal carbonization (HTC) at 140, 160, 180, and 200 °C.
• Proximate analysis, ultimate analysis, and phytotoxicity tests.

Main Results:

• Biochar exhibited higher carbon stability, suitable for carbon sequestration.
• Hydrochar contained more labile carbon structures.
• Both biochar and hydrochar demonstrated positive effects on wheat seed germination and increased surface hydrophobicity compared to FS.

Conclusions:

• FS-derived biochar and hydrochar represent a viable waste valorization pathway.
• These materials offer potential for soil amendment and carbon sequestration applications.
• This research supports the development of a circular economy and zero-waste targets in water treatment.