10.48788/DVUA/CFSY4T Ostroha, Ruslan0000-0003-0045-3416(Sumy State University)Mija, Alice0000-0001-5208-5956(Université Côte d'Azur)Cibotaru, Sandu0000-0002-9080-9502(Université Côte d'Azur)Skydanenko, Maksym0000-0002-0277-1867(Sumy State University)Bataltsev, Yevhen0000-0003-2035-2014(Sumy State University) DataverseUA 2025 This dataset contains graphical representations (.png) of FTIR spectra for four organic and organo-mineral samples. The spectral analysis was performed to identify functional group changes during the valorization of digestate. List of analyzed samples: Peat (Reference material) Solid Digestate (Raw material from anaerobic digestion) Digestate Biochar (Pyrolyzed digestate) Digestate + (NH4)2SO4 (Organo-mineral fertilizer enriched with ammonium sulfate) Methodology: The FTIR spectra were recorded using a Nicolet iS50 FT-IR spectrometer (Thermo Fisher Scientific, USA) equipped with a GladiATR diamond ATR accessory (PIKE Technologies, USA). Measurements were performed at a resolution of 2 cm-1, with 32 scans, in the spectral range of 4000–600 cm-1. Ostroha, Ruslan(Sumy State University)