Treatment of fish canning wastewater by electrochemical oxidation process
Imen Souli, César Afonso, Ana Lopes, Maria José Pacheco, Lurdes Ciríaco, Lazhar Labiadh, Salah Ammar, Annabel Fernandes
Abstract
The high organic load and the salinity content presented by fish canning wastewater (FCW), although a hindrance to the application of traditional treatment processes, are favourable conditions for the treatment by electrochemical oxidation (EO). In this study, the performance of EO treatment of FCW at different applied current density (j) and electrical charge, using a boron-doped diamond (BDD) anode, was evaluated regarding organic load, nitrogen, and phosphorous removals, biodegradability increment, toxicity reduction, and specific energy consumption. Experimental results showed that, for the range of the applied j studied, the efficiency of the process only depends on the applied electrical charge and that EO, with BDD anode, can effectively promote the depuration of the highly polluted FCW without requiring the addition of chemicals. After an applied charge of 60.5 kC, treated wastewater was obtained with a chemical oxygen demand of 130 mg L−1, a biodegradability index of 0.90, and a 2.8-fold reduction in toxicity towards Daphnia magna. Moreover, 80 % of nitrogen and 60 % of phosphorous removal were attained, foreseeing the potential recovery of nutrients through electrochemically mediated precipitation.