Li, et al (2024) Insights into the characteristics and toxicity of microalgal biochar–derived dissolved organic matter by spectroscopy and machine learning. Science of The Total Environment. https://doi.org/10.1016/j.scitotenv.2024.177648

Microalgal 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 is a promising material for environmental applications like soil improvement and wastewater treatment, but understanding its dissolved organic matter (MBDOM) is crucial due to potential environmental risks. A recent study explored how pyrolysisPyrolysis is a thermochemical process that converts waste biomass into bio-char, bio-oil, and pyro-gas. It offers significant advantages in waste valorization, turning low-value materials into economically valuable resources. Its versatility allows for tailored products based on operational conditions, presenting itself as a cost-effective and efficient More temperature and extraction methods impact the characteristics and toxicity of MBDOM derived from three types of microalgae.

Using advanced spectroscopy and machine learning, the research revealed that higher pyrolysis temperatures (500°C vs. 200°C) reduced levels of dissolved organic carbon (DOC), total nitrogen (TN), and total phosphorus (TP) while increasing total potassium (TK). Extraction solutions also played a role: alkaline solutions promoted DOC and TN release, whereas acidic solutions enhanced TP and TK release.

MBDOM from low-temperature pyrolysis and alkaline extraction was found to be particularly toxic to Photobacterium phosphoreum T3, a bioluminescent bacterium used for toxicity testing. Machine learning models identified TN and DOC as key factors driving toxicity, alongside molecular weight and aromaticity.

The study underscores the importance of optimizing production parameters to minimize environmental risks associated with MBDOM. By linking chemical properties to toxicity, this research provides valuable insights for safer and more effective applications of microalgal biochar in environmental management.

These findings highlight the need for careful evaluation of MBDOM properties before large-scale biochar use to balance its benefits with potential ecological impacts.