ABSTRACT
The use of digestate as a fertilizer to replace inorganic fertilizer is crucial in terms of both economics and ecology. However, pathogenic fungi could still be present in the digestate, making it unsafe for the environment. The purpose of this study was to ascertain the time-temperature requirements for fungal load reduction in digested cow dung and its safety as a bio fertilizer. The National Centre for Energy and Environment at the University of Benin in Benin City, Edo State, Nigeria provided the cattle rumen digestate slurry (CRD). The digestate was heated to varied temperatures of 0, 55, 60, 70, and 80 °C for 0, 20, 30, 40, and 60 minutes. The analyses carried out were fungal load using potato dextrose agar (PDA), physicochemical and heavy metal content. From the results, the lowest fungal load was from digestate exposure at 80 ℃ for 60 min. These counts were observed to be below the allowable limits of fungal contamination in digestate for agricultural land application as bio fertilizer. Concentrations of nitrate, TK, TKN were highest at 60 ℃ and 80 ℃, TAN and TP were highest at 70 ℃ and 55℃ respectively, while 70 oC, heavy metals were lowest. From this present study, the heat treatment of cattle rumen digestate has shown significant increase in its nutrients and reduced amount of fungi and heavy metals, thereby increasing its quality and making it suitable as a bio fertilizer safe enough to apply to farmland.
