Cork boiling wastewater treatment at pilot plant scale: Comparison of solar photo-Fenton and ozone (O3, O3/H2O2). Toxicity and biodegradability assessment

Remediation of cork boiling wastewater was studied as an example of complex industrial wastewater treatment by applying a protocol based on a combination of advanced technologies and chemical-biological assays. Solar photo-Fenton and ozone (alone or in combination with hydrogen peroxide at different pH conditions), at pilot plant scale have been used as chemical oxidation step. Additionally, the effect of a physic-chemical pre-treatment using different flocculants (FeSO4 and FeCl3) was evaluated. Although physic-chemical pre-treatment with Fe3+ provided good removals of COD, DOC and TSS, it was found that it did not enhance solar photo-Fenton post-treatment. On the contrary, ozone-based process was improved after physic-chemical pre-treatment with Fe3+, attaining higher degradation efficiencies with lower ozone consumptions for the combination with O-3 at initial pH 7. Toxicity and biodegradability assays were performed to evaluate possible variations along the oxidation processes. After solar photo-Fenton treatment, toxicity and biodegradability remained constant at their initial values. Then, Zahn-Wellens test was carried out to study long term biodegradability and possible biomass adaptation to the partially photo-treated effluent. Decrease in toxicity values and short term biodegradability enhancement were observed for cork boiling wastewater treated by ozonation systems. (C) 2013 Elsevier B.V. All rights reserved.