Valorization of phenolic compounds from brewery wastewater: Performances assessment of ultrafiltration and nanofiltration process with application of HPLC coupled with antioxidant analysis tool

Phenolic-rich brewery alkaline wastewater sustainable valorization with membrane technology was investigated. Intensified process of preselected ceramic 15 kDa ultrafiltration and 200 Da nanofiltration membranes was studied at pH 4, 6.5, 10 and 13.5 to prospect the best operation conditions of phenolic compounds (PC) recovery and water reclamation process regarding fouling inclination, productivity and selectivity performances. Flux-limiting phenomena propensity according to pH were investigated. HPLC coupled with online antioxidant capacity innovative analysis was used to assess PC selectivity behavior and its subsequent impact on antioxidant properties of concentrated wastewater. Flux-limiting phenomena consisted of PC, carbohydrates and proteins pore blocking and cake layer during ultrafiltration and was corroborated to pH acidity. Osmotic pressure due to ions concentration polarization was predominant during nanofiltration and was lower during pH 4 and 13.5 due to membrane characteristics. PC selectivity by ultrafiltration and nanofiltration membranes was determined with compounds size and chemistry, along with pH effect on molecules and membrane charges. The chemical structure of single PC led to differential segregation through the valorization process, and thus to modification of the antioxidant profile of concentrated wastewater. pH 13.5 showed controlled fouling development and advantageous selectivity and productivity performance, and nanofiltration yielded concentrated PC retentate for resource recovery and clarified permeate for water and alkalis reclamation.