Anaerobic Digestion Unlocks the Potential of Cork Boiling Wastewater (CBW)

Cork boiling wastewater (CBW) is a toxic and organic effluent produced by the cork industry, which is a serious environmental hazard. Similar to other agro-forestry waste materials, CBW contains potential high value by-products useful for industrial applications. There is no documented research, however, on anaerobic treatment or valorization performed with this effluent. Recently, a group of researchers from Laboratório Nacional de Energia e Geologia in Portugal aimed to use anaerobic digestion to convert CBW into an energy carrier gas and a source of valuable molecules.

A methane yield of 0.126 to 0.142 m3 per kg chemical oxygen demand (COD) was registered by CBW in studies carried out in batch flasks at 37°C. There was an observed reduction in ellagic acid content and decrease in CBW viscosity. This allows the ultrafiltration of the effluent. There was also a conductivity increase, which will provide cheaper conditions to completely remove the remaining organic load, using electrochemical techniques as post-treatments. The additional production of valuable and useful molecules is another interesting aspect offered by anaerobic digestion.

By taking advantage of the potentials of the anaerobic digestion process, a new methodology to detoxify wastewater was developed.