Decomposing the molecular complexity and transformation of dissolved organic matter for innovative anaerobic bioprocessing.

The sustainable transformation and management of dissolved organic matter (DOM) are crucial for advancing organic waste treatment towards resource-oriented processes. However, the intricate molecular complexity of DOM poses significant challenges, impeding a comprehensive understanding of the underlying biochemical processes. Here, we focus on the chemical "dark matter" mining using ultra-high resolution mass spectrometry technologies to elucidate the molecular diversity and transformation in anaerobic bioprocessing of food waste. We developed an analytical framework that reveals the persistence of DOM in the final effluent is mainly determined by its molecular properties, such as carbon chain length, aromaticity, unsaturation, and redox states. Our in-depth characterization and quantitative analysis of key biochemical reactions unveils the evolution of DOM composition, providing valuable insights into the targeted conversion of persistent molecules toward full utilization. Additionally, we establish a correlation between the redox state and energy density of a broad range of DOM molecules, enabling us to comprehend and evaluate their biodegradability. These insights enhance the mechanistic understanding of DOM transformation, guiding the rational design and regulation of sustainable organic waste treatment strategies.