Optimization and modeling of two-phase olive-oil washing wastewater integral treatment and phenolic compounds recovery by novel weak-base ion exchange resins

In light of the Circular Economy concept, recently emerged as a need for sustainable production, olive oil industry should be concerned to transform the whole process into environmentally friendly, which necessarily implies the treatment of the wastewater by-produced in olive mills. In this work, concentration and recovery of high-added value phenolic compounds from two-phase olive-oil washing wastewater (OOWW) and parallel effluent treatment by a 'green process' based on novel weak-base ion exchange (IE) resins was addressed. The key operating input factors of the resin process for the treatment and valorization of OOWW were studied, optimized and further modelled. A Box-Behnken design was implemented and the obtained data were analyzed by ANOVA and interpreted by RSM methodology. The process was ulteriorly modelled by a second-grade quadratic fitting equation comprising the significant operating variables. The optimization of the IE process performance (20.3 degrees C, pH(0) 6.7 and 114 g/L M-resin) ensured up to 92.5% recovery of total phenols concentration. Moreover, the purified stream presented good quality (56.6-83.7 mg L-1 total phenols), following standard recommendations by the FAO. The obtained information would be of key importance for the scale-up of the proposed IE operation. Both the treatment and revalorization of OOWW would help implement a definite sustainable production process of olive-oil.