In situ probing methanogenesis in anaerobic wastewater treatment using front-face excitation-emission matrix (FF-EEM) fluorescence

Global warming and the energy crisis give rise to increasing demand for renewable energy production and resource recovery. Anaerobic methanogenesis, which transforms organic matter to methane, is the pivotal step in most resource-sustainable applications in wastewater treatment, while its evaluation and monitoring are still challenging. This study proposed a novel approach for probing methanogenesis in anaerobic wastewater treatment by in situ determining coenzyme F420 using front-face excitation-emission matrix (FF-EEM) fluorescence spectroscopy. The results indicated that the proposed method was simpler and more accurate than the conventional F420 measurement. The parallel factor analysis (PARAFAC) and the internal standard correction were used to address the fluorescence overlap and the inner-filter issues, respectively. The F420 fluorescence determined by the FF-EEM correlated well with the methane yield rate (R² = 0.882) and the mcrA gene (R² = 0.847), and it could be associated with the methanogenic activity of the anaerobic sludge. This study demonstrated that the FF-EEM-based method was promising in evaluating methanogenesis in anaerobic process, and could assist in the optimization of bioresource recycling in wastewater treatment.