This article links to the main piece on HealthySoil which explains the broader shift in biochar markets and carbon credits. Here, we focus specifically on what that shift means for biochar filtration systems.
The key issue for filters
As carbon markets push production toward high-carbon, high-aromatic biochar, a critical point is being overlooked:
The properties that maximise carbon credits are not the same as those that optimise filtration performance.
This does not mean that high-carbon biochars have no role in filtration. In some cases, their stability and structure may be beneficial. However, filtration performance depends on specific physical and chemical characteristics that are not guaranteed by carbon metrics alone.
Biochar is a material class, not a single filtration media
Biochar properties used in filtration emerge from the interaction of:
- feedstock
- process conditions
- post-processing or activation
Treating biochar as a single material obscures this functional diversity.
Stop saying “biochar for filtration”
Filtration performance depends on:
- particle size distribution
- pore size distribution (micro, meso, macro)
- accessible surface area
- surface chemistry and functional groups
Filtration performance is governed by these properties, not carbon content alone.
Two biochars can behave completely differently in water or air treatment systems.
Feedstock and production matter
Production systems designed for carbon credits typically require:
- clean, uniform feedstock
- high-temperature processes
However, filtration systems may require:
- tailored pore structures
- specific surface chemistry
- controlled particle sizing and activation
The risk
If production is driven only by carbon-credit optimisation:
- filtration performance may be compromised
- materials may be over-specified for the wrong function
The correct approach
Define the function first, then design the biochar.
For filtration this means specifying:
- target contaminants
- required adsorption characteristics
- hydraulic performance
Link to main article
For the full discussion on carbon markets, feedstock constraints, and system trade-offs, see the main article on HealthySoil.
Summary
Biochar used in filtration is an engineered material. The future lies in designing biochar to meet specific filtration requirements, not assuming all biochar behaves the same.