Influence of Molecular Size on the Electrochemical Oxidation of Fractioned Cork Boiling Wastewater

The performance of electrochemical oxidation (EO) using a boron doped diamond (BDD) anode was assessed for cork boiling wastewater (CBW) molecular size fractions of >100kDa, 50-100kDa, 20-50kDa, 10-20kDa and <10kDa, obtained through sequential use of ultrafiltration (UF) membranes. The best EO results were found in the experiments performed with no addition of supporting electrolyte and at the lowest applied stirring speed, the more economical and environmentally friendly conditions. The highest EO treatment efficiency was observed for the fraction >100kDa, which presented also the highest organic load. EO treatment led to an increase in the biodegradability of the fraction >100kDa and to a decrease in the biodegradability of the fraction <10kDa. Moreover, samples toxicity was not affected by the EO process, suggesting that the treated samples can be forwarded to biological post-treatment processes. UF fractionation showed to be advantageous in combination with EO, since it enables the selective use of EO where it is more effective regarding biodegradability and current efficiency.