Shirani, et al (2024) Efficiency and ecotoxicity of activated biocharBiochar is a carbon-rich material created from biomass decomposition in low-oxygen conditions. It has important applications in environmental remediation, soil improvement, agriculture, carbon sequestration, energy storage, and sustainable materials, promoting efficiency and reducing waste in various contexts while addressing climate change challenges. More in the treatment of artificial wastewater contaminated by pharmaceuticals. Journal of Environmental Management. https://doi.org/10.1016/j.jenvman.2024.123224

Activated biochar (ACB) shows promise in treating wastewater contaminated with pharmaceuticals like diclofenac (DI), tetracycline (TE), and cephalexin (CEP). This study evaluated its removal efficiency and ecotoxicological impacts using Daphnia magna as a test species.

Results revealed that ACB efficiently removed pharmaceuticals at higher concentrations but was less effective at lower levels and in complex artificial wastewater (AWW) due to competitive interactions between wastewater components and pharmaceuticals. In AWW, the removal rates for DI, TE, and CEP dropped significantly compared to purified water, likely due to electrostatic repulsion and site occupation by other constituents.

The study also investigated ACB’s toxicity before and after adsorbing pharmaceuticals. Pristine ACB exhibited significant toxicity to Daphnia magna, causing immobilization due to its reactive free binding sites and sharp surface structure. However, ACB loaded with pharmaceuticals (ACB-LP) was less toxic, as the adsorbed compounds appeared to reduce its harmful properties.

While ACB-LP from AWW was generally less toxic, certain combinations, such as CEP-loaded ACB, posed higher risks due to incomplete pharmaceutical adsorption and persistent reactive sites. Observations suggested that the physical and chemical interactions between ACB and aquatic organisms could impair survival.

This study highlights the dual role of ACB: a potential tool for pharmaceutical removal and a potential ecological hazard. The findings underscore the importance of further research on its long-term impacts and optimization for safer wastewater treatment practices.