Interactive impact of Myrothecium verrucaria and MnO2 on fertilizer quality and biological safety of anaerobic digestate

Abstract

Low contents of the active compound and high pathogens counts are considered the major factors hampering land application of anaerobic digestate. Therefore, the role of Myrothecium verrucaria and MnO2 treatment in enhancing fertilizer quality and biological safety of digestate for land application was explored. Higher contents of humic acid (8.9 g/L) with a higher degree of humification index and oxygen-containing functional groups was observed in the digestate receiving Myrothecium verrucaria coupled with MnO2 treatment. Moreover, the viable and culturable count of S. faecalis, S. typhi, C. perfringens, and E. coli pathogens in the digestate decreased approximately to 12.50%, 41.70%, 18.87%, 50.00% and 25.97%, 64.44%, 37.51%, 75.27%, respectively after treatment with Myrothecium verrucaria and MnO2. However, the count of pathogens in the VBNC (viable but not culturable) state increased from 3.75%-9.44% to 28.25%–54.01% after treatment. This study provided a novel strategy to enhance the fertilizer quality and biological safety of anaerobic digestate for land application.