The recent discovery of a deep-sea oxygen source has stunned marine researchers and may necessitate a radical rethinking across several scientific fields, including the search for extraterrestrial life. Unlike the oxygen produced by photosynthesis, this oxygen is generated by minerals on the ocean floor.

High school science classes often teach that our oxygen comes from plant photosynthesis, particularly in tropical rainforests. However, scientists have long known that this is only partly true. While plants do produce a significant portion of the oxygen we breathe, phytoplankton in oceans and lakes contribute substantially as well. In both cases, the basic process involves living organisms using sunlight to convert carbon dioxide and water into necessary molecules, producing oxygen as a byproduct. This oxygen is crucial for sustaining life on Earth, including human life.

Creating fertilizers from organic waste can significantly reduce fossil fuel consumption and promote sustainable agricultural production. One innovative method is hydrothermal liquefaction (HTL), which converts biomass into biocrude oil through a high-temperature, high-pressure process. Two studies from the University of Illinois Urbana-Champaign explore the use of a fungal treatment to convert the leftover wastewater from HTL into fertilizer for agricultural crops.

“HTL uses wet biomass from organic sources such as swine manure or food waste. The process yields wastewater, called hydrothermal liquefaction aqueous phase (HTL-AP), which is usually discarded. We know it contains nutrients that can be used for fertilizer, but they are mostly in organic forms that plants can’t access. HTL-AP may also contain toxic heavy metals, depending on the type of biowaste,” said co-author Paul Davidson, an associate professor in the Department of Agricultural and Biological Engineering (ABE), part of the College of Agricultural, Consumer and Environmental Sciences and The Grainger College of Engineering at Illinois.