Penn State University researchers are exploring the efficacy of natural biochar to absorb pharmaceutical contaminants from wastewater to prevent the chemicals’ entry into soil and subsequent uptake by food crops. The research is being funded by the U.S. Department of Agriculture’s Agricultural Research Service (USDA’s ARS).

In an interview with ARS, graduate student Carla Ndoun Tangmo explains that approximately 70 percent of the pharmaceuticals taken by humans are excreted and ends up in wastewater. This leads to the transfer of pharmaceuticals into bodies of water and soil, as the technology in place to clean this wastewater is not equipped to remove pharmaceuticals. The substances can then accumulate in the edible parts of plants, leading to concerns over potential toxicity to humans, particularly for food products that are consumed raw.

Additionally, when pharmaceuticals enter soil, the chemicals can interact with the environment and transform into more harmful substances. Continuous accumulation and persistence of pharmaceuticals in the environment can lead to negative health consequences such as interference with endocrine systems and increased antimicrobial resistance in bacteria.

Biochar is similar to charcoal, and it is produced from burning waste at high temperatures. To study its efficacy in filtering pharmaceuticals, the Penn State researchers are using cylindrical glass columns filled with 8 grams of biochar and 8 grams of sand. A pharmaceutical mixture is then added to the columns slowly over 24 hours, and samples are collected periodically. The samples are analyzed for the concentration of pharmaceuticals after filtration to estimate how much of the pharmaceutical solution was removed. Although the efficacy of biochar filtration varies depending on the pharmaceuticals being filtered, the Penn State researchers have observed up to a 95 percent removal rate of the chemicals after 24 hours.

The researchers believe that biochar can serve as a tool to address current and future water and food contamination issues, especially in resource-limited communities.