Characterisation of the recalcitrant organic compounds in leachates formed during the anaerobic biodegradation of waste.

This study investigates the use of UV absorption and fluorescence spectroscopy to assess the early development of recalcitrant organic compounds in leachates formed during the anaerobic biodegradation of municipal solid waste. Biochemical methane potential tests were carried out on fresh waste (FW) and composted waste (CW) over a period of 150 days and leachates produced from the degradation of two wastes were analysed for humic-like (H-L) and fulvic-like (F-L) structures by UV spectroscopy and fluorescence excitation-emission-matrix analyses. During anaerobic biodegradation, the synthesis and utilization of H-L and F-L structures in the leachates over time was indicative of the generation of the recalcitrant organic compounds. The results obtained from UV absorption and fluorescence spectroscopy suggested that CW leachates resulted in a higher concentration and more condensed form of recalcitrant H-L and F-L molecules than FW leachates. These findings demonstrate how fluorescence and UV absorption spectroscopy can be used as an indicator for monitoring the evolution of recalcitrant organic compounds (H-L and F-L substances) in leachates formed at different stages of waste biodegradation.