Productivity, selectivity performances and fouling control of brewery wastewater micro-ultrafiltration through operation optimization and membrane screening

Abstract

A brewery wastewater was identified as phenolics-rich stream, representative of agro-food wastewaters. This latter can be used to develop a more sustainable brewery industry by recovering bioactive molecules and reusing water. Seven ceramic (TiO2-ZrO2) and organic (PVDF and PES) membranes with cut-off ranging from 15 kDa to 0.2 μm were assessed for their brewery wastewater clarification capacity, which is a key step allowing high natural resource recovery with further downstream process. Six criteria were used to evaluate membrane productivity (permeate volume), selectivity (turbidity and carbohydrates removal, phenolic compounds preservation) and robustness (inclination to fouling, ease of cleaning) at pH 4 and 10. Membranes with cut-off equal or larger than 0.1 μm were identified as improper due to high and irreversible fouling. With ultrafiltration membranes, pH 4 showed higher fouling propensity, due to reinforced fouling-causing molecules electrostatic interactions, than pH 10. Turbidity-causing compounds retention was higher than 83 %, phenolics were preserved with retention factors lower than 22 %. Carbohydrates retention was between 2 and 23 %. Therefore, through a screening methodology developed to meet a set of industrial requirements, the following classification of global performances is proposed: 15 kDa TiO2-ZrO2 > 70 kDa PVDF >150 kDa TiO2-ZrO2 > 50 kDa PES.