Valorization of Used Toraja Coffee Powder (C. Ara-bica) Through Acid Extraction and NanofiltrationHeru Susanto, Assalaam Umar Abdurahman, Muhamad Nataprawira, Faghi Suwandi, Vares Dodi and Titik IstirokhatunE3S Web Conf., 655 (2025) 04001DOI: https://doi.org/10.1051/e3sconf/202565504001