Agricultural manure has been connected to higher-than-normal levels of nitrogen and phosphorous, antibiotics, heavy metals, and hormones in surface and groundwater downstream from facilities.

In order to deal with the problem, a Texas A&M researcher, Dr. Eunsung Kan, is researching the viability of a closed-loop dairy farm.

Dairy farms can recycle manure for a variety of uses.The concept includes three main goals: treat wastewater with dairy manure-derived biochar; produce energy by using the char; and capture greenhouse gases by using the char for adsorption.

Biochar, a carbon material similar to charcoal, could be created from animal manure and agricultural waste, such as corn stubble or rice straw. Columns filled with biochar could act as a water filtration system that filters nitrogen, phosphorous and other contaminants from wastewater. The biochar could then be used as a slow-release fertilizer to provide nutrients to plants.

In addition, Kan reportedly has demonstrated that biochar immobilized with photocatalysts could decompose toxic contaminants to harmless products when irradiated by exposure to ultraviolet light. It completely degraded antibiotic and hormone compounds while effectively controlling pathogens. Beyond agriculture, it could possibly be used as a filter at wastewater treatment plants.

In order to create the biochar, dairy manure would be fed into a pyrolysis reactor, which would be driven by heat in the range of 500–1000 degrees Fahrenheit. In addition to biochar, pyrolysis creates compressed hydrogen and carbon monoxide syngas, which can be used to generate electric power to power the facility, with any excess being sold back to local utilities. The syngas can also be biologically converted to butanol and bio-jet fuel for use in transportation.

Kan says he plans to test his closed-loop dairy concept at the Southwest Regional Dairy Center, a privately owned working dairy operated by Tarleton State University. He hopes to have a system, including the pyrolysis reactor, operating at the dairy within three to four years.