Relationship between anaerobic digestion of biodegradable solid waste and spectral characteristics of the derived liquid digestate

The evolution of spectral properties during anaerobic digestion (AD) of 29 types of biodegradable solid waste was investigated to determine if spectral characteristics could be used for assessment of biological stabilization during AD. Biochemical methane potential tests were conducted and spectral indicators (including the ratio of ultraviolet–visible absorbance at 254 nm to dissolved organic carbon concentration (SUVA254), the ratio of ultraviolet–visible absorbance measured at 465 nm and 665 nm (E4/E6), and the abundance of fluorescence peaks) were measured at different AD phases. Inter-relationship between organic degradation and spectral indicators were analyzed by principle component analysis. The results shows that from methane production phase to the end of methane production phase, SUVA254 increased by 0.16–10.93 times, the abundance of fulvic acid-like compounds fluorescence peak increased by 0.01–0.54 times, the abundance of tyrosine fluorescence peak decreased by 0.03–0.64 times. Therefore, these indicators were useful to judge the course of mixed waste digestion.