Is sewage sludge biochar the miracle that Saratoga Biochar claims it would
be?
Is sewage sludge biochar the miracle that Saratoga Biochar claims it would
be?
A Backgrounder from Clean Air Action Network of Glens Falls, Feb. 2024
1. 50 percent of the carbon is released as carbon dioxide during the pyrolysis
process, making the efficiency highly questionable. Pyrolysis is the thermal
process that the plant would use to turn sewage sludge into charcoal.
2. Regardless of the feedstock, during pyrolysis, polycyclic aromatic
hydrocarbons (PAHs) are formed, which are carcinogenic and mutagenic.
These pollutants cannot be removed from biochar because they are too
strongly bonded to the material. In addition, they are usually not measured
when pollutants in biochar are analyzed because they are not extractable.
These harmful PAHs can be released into the air during pyrolysis or to the soil
over time.
3. The European Union prohibits the use of sewage sludge to produce biochar.
4. The jury is out on whether biochar is helpful or harmful to soil. Scientific
studies show that the effects of biochar on soil carbon and soil fertility in field
trials are highly variable, depending on soil properties and biochar production
methods and feedstock.
5. Making biochar is energy-intensive and results in high air emissions,
including the greenhouse gas carbon dioxide.
6. Biochar does not directly feed soil organisms. Soil organisms are responsible
for managing the carbon and nutrient cycles in soil and building healthy living
soil. Soil organisms require degradable carbon substances to function, but
biochar is a coal-like substance.
7. Biochar may contain persistent contaminants that pollute the soil, including
poly aromatic cyclic hydrocarbons (PAHs), dioxins, PCBs, heavy metals, and
PFAS “forever chemicals.”