Processo multistadio per la valorizzazione di acque di vegetazione dalla produzione di olio di oliva: recupero di composti fenolici, digestione anaerobica e valutazione economico-ambientale

Olive mill wastewaters (OMWs) are an environmental concern due to their high organic load and phytotoxic activity, but they are rich of phenolic compounds (PCs) and their recovery is interesting, thanks to their antioxidant and antimicrobial properties. The anaerobic digestion of the resulted dephenolized water (D-OMW), in order to produce methane and to obtain a treated water for irrigation, is an additional advantage. The goal of this work is to propose an integrated process of PCs recovery through an adsorption step (evaluated also with LCA-CBA) and anaerobic digestion of D-OMW. Two resins (XAD16 and IRA958 in OH form) were compared with semicontinuous-flow adsorption/desorption tests conducted in a 1-m packed column. A test was also conducted with a mixed bed of the two resins. The D-OMWs resulted from the previous tests were then used for anaerobic digestions. The LCA confirms the possible decreasing of the environmental impact of the process through the addition of an anaerobic digestion step for the production of irrigation water from dephenolized OMW, while the PC market price needed for a positive business case is reasonable. The results indicate that the proposed PC adsorption/desorption technology, if integrated with an anaerobic digestion step, which has an optimal methane yield, represents a promising solution for the treatment and valorisation of OMWs.