Study suggests biochar could significantly improve anaerobic digester performance
In a paper by Texas A&M scientists, biochar shows potential for increasing efficiency of the anaerobic digestion of animal manure.
Biochar is a charcoal material composed of agricultural by-products, including manure, crop residues and grasses. The substance can be used as a fertiliser and as a filter to remove contaminants from water and wastewater, including antibiotics, pesticides and hormones; in the process, biochar captures CO2 and ammonia.
“There are good indications that biochar will make anaerobic digestion a viable solution for more efficient management of animal manure with easier operations than conventional anaerobic digestions,” said Dr. Eunsung Kan, co-author of the study in a statement. “When we optimise conditions and move to the test phase on a dairy then we will know what capital investment and footprint would be necessary to build sustainable digesters that can meet the disposal needs and then apply that to other operations based on their capacity.”
In the study, digesters that are enhanced with the biochar saw a methane production increase of about 40%, with a reduction in production time of 50-70%.
Kan said that these savings could lower initial investment costs, water consumption, utility costs, operating costs and land requirements. But he added that more research is needed into how microbial communities behave in the presence of biochar and what the optimum conditions are for biogas production.
"There are good indications that biochar will make anaerobic digestion a viable solution for more efficient management of animal manure with easier operations than conventional anaerobic digestions," he said. "When we optimise conditions and move to the test phase on a dairy [farm] then we will know what capital investment and footprint would be necessary to build sustainable digesters that can meet the disposal needs and then apply that to other operations based on their capacity."
