By April Day,  Publishing Consultant at Save the Water™ | October 31, 2025

Edited by Shannon Hsieh, Publishing Associate: Editor, at Save the Water™

Biomass is plant and animal material used as fuel. Biochar refers to what remains after burning biomass quickly at high temperatures in low oxygen environments. Charcoal is an example of biochar. Biochar can absorb pollutants. As a result, traditional water treatments use biochar to remove pollution. 

‍Dr. Gao and other scientists at Dalian University of Technology published a recent study about using biochar alone to remove water pollution. Their findings suggest that biochar is a greener way to treat water compared to traditional water treatments.

How is Biochar Usually Used to Remove Pollution from Water?

Water systems use biochar to treat water in two ways: 

• as an adsorbent 
• as a catalyst

Biochar’s Use as an Adsorbent ‍

An adsorbent is a material that can select, capture, and retain substances. People use biochar in this way to treat wastewater. After the biochar absorbs pollutants as much as it can, people discard the biochar.

Biochar’s Use as a Catalyst ‍

Some water treatment processes rely on oxidants to work.  Simply stated, oxidants are substances that accept electrons from other substances. People also use biochar as a catalyst for oxidants to produce reactive oxygen species such as HO, SO₄-, O₂-. This is how biochar is used in traditional, advanced oxidation processes. These processes require oxidants to degrade organic pollutants. 

However, Dr. Gao’s new study found that biochar doesn’t need oxidants to directly degrade organic pollutants. Which is to say, biochars alone can directly and indirectly destroy pollution. 

How did the Scientists Study Biochar?

Dr. Gao and the other scientists set up experiments to study the relationship between biochar characteristics and the direct degradation performance of biochar without any oxidants. They focused on structure and performance. 

The scientists found that biochar’s direct degradation capacity is highly related to its electron donating capacity.  Notably, they found that oxygen directly competes with pollutants for electrons. This competition decreases biochar’s efficiency for direct degradation. 

In addition, Dr. Gao and the other authors concluded that “pore filling played an important role for the removal of organic pollutants.” 

How Good is Biochar at Destroying Water Pollution? ‍

For five consecutive cycles, biochar degraded 40%, plus or minus 10%, of all pollutants destroyed. In other words, biochar alone got rid of between 30% and 50% of all pollutants destroyed. This was a stable rate. After five cycles, however, the biochar’s performance declined as there were fewer reactive active sites.   

What does this Mean? ‍

In short, Dr. Gao and the other scientists at Dalian University of Technology made findings that provide real world solutions to problems with treating wastewater. 

These solutions are as follows: ‍

• Fewer Chemicals: Biochar allows wastewater treatment without as many chemicals as current methods. This is good. In short, adding chemicals to water can make more problems. For example, people have to think about additional chemical reactions. This was one of the problems in Flint, Michigan. Adding more chlorine without other treatments led to high levels of cancer-causing chemicals. By contrast, biochar doesn’t add more chemicals. Biochar doesn’t have this problem. 
• Sludge: Sludge is the stuff left after treating water. Specifically, sewage sludge “comes from the solid wastes separated during wastewater treatment.” Which is to say, people still need to deal with it after treating wastewater.  Although sludge is itself a byproduct of treating wastewater, sludge also contributes to water pollution. Getting rid of biochar is cheaper than dealing with sludge.
• ‍Less Energy Use: Biochar is a greener purification system for removing pollutants from wastewater. So far, people use biochar as a sponge only. But it can destroy pollution directly. This uses less energy.

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