Treatment of table olive processing wastewaters using novel photomodified ultrafiltration membranes as first step for recovering phenolic compounds

• Published in: Journal of hazardous materials 2015-06, Vol.290, p.51-59
• Main Authors: Garcia-Ivars, Jorge, Iborra-Clar, Maria-Isabel, Alcaina-Miranda, Maria-Isabel, Mendoza-Roca, José-Antonio, Pastor-Alcañiz, Laura
• Format: Article
• Language: English
• Subjects: Aluminum Oxide - chemistry; Antifouling; Biological Oxygen Demand Analysis; Hydrophilicity; Indicators and Reagents; Industrial Waste; Membranes, Artificial; Olea; Olive wastewater; Phenolic compound; Phenols - chemistry; Phenols - isolation & purification; Photochemistry; Polyethylene Glycols - chemistry; Spectrophotometry, Ultraviolet; Spectroscopy, Fourier Transform Infrared; Surface modification; Ultrafiltration; Waste Disposal, Fluid - methods
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2015.02.062

•UF process is a useful tool for reducing colour and organic load from TOPW.•UV modification was performed to enhance fouling-resistant membrane capability.•FTIR-ATR and water contact angle were measured to ensure the modification process.•Effect of PEG and Al2O3 on membrane performance was investigated.•Membranes modified with Al2O3 reduced the phenolic content in the concentrate stream. Table olive processing wastewaters (TOPW) have high salt concentration and total phenolic content (TPC) causing many environmental problems. To reduce them, ultrafiltration (UF) was applied for treating TOPW. However, NaCl, which is the main responsible of salinity in TOPW, and phenols are small molecules that cannot be separated by conventional UF membranes. They have serious problems caused by fouling, which can be overcome using membrane modification techniques. For these reasons, photomodification may be an effective technique to obtain a stream rich in TPC due to the changes in membrane surface properties. UV-modification in the presence of two hydrophilic compounds (polyethylene glycol and aluminium oxide) was performed to achieve membranes with high reductions of organic matter and to keep the TPC as high as possible. Commercial polyethersulfone (PES) membranes of 30kDa were used. Surface modification was evaluated using FTIR-ATR spectroscopy and membrane performance was studied by calculating the rejection ratios of colour, chemical oxygen demand (COD) and TPC. Results demonstrated that UF is a useful pre-treatment to reduce organic matter from TOPW, obtaining a permeate rich in TPC. PES/Al2O3 membranes displayed superior antifouling properties and rejection values, keeping high the TPC (>95%). Therefore, UF using modified membranes is an appropriate and sustainable technique for treating TOPW.