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CIEPQPF

Chemical Process Engineering and Forest Products Research Centre

Session 18

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Research Seminar #18, Apr 09, 2014, 14h15-15h15h

Seminar Presentation

Ana Sofia Fajardo, "Electrocoagulation: a new approach to treat wastewaters"

Olive mill wastewaters are mainly produced in Mediterranean countries and contain phenolic mixtures in their composition. These compounds incorporate a significant contaminant load due to their high toxicity, refractory character and high stability in water. These factors do not allow an efficient application of biological treatments so that the recourse for chemical purification methods is requested before the effluents’ discharge into the aquatic environment.

Electrochemical processes appear as interesting alternatives to conventional systems to treat wastewaters, allowing a great efficacy in the removal of organic compounds. Among these technologies is electrocoagulation (EC), easy to operate, requiring low equipment costs, not needing high temperature and pressure. In the EC system, sacrificial anodes dissolve into the aquatic medium leading to the generation of metal ions which are hydrolysed to produce metal hydroxide ions. The in-situ generation of coagulants has the advantage of not being required the introduction of chemical reagents to the system.

The electrocoagulation process has begun to be successfully applied to the treatment of olive mill wastewaters with the aid of anodes of aluminium or iron material.

The main objective of this research was to compare the effect of Al, Fe, Cu, Pb and Zn anode materials on the treatment of a mixture of six phenolic acids usually present in olive mill wastewaters. The assessment of their activity is given in terms of Total Phenolic Content (TPh), Chemical Oxygen Demand (COD), Biochemical Oxygen Demand (BOD5) removal and effluent toxicity. Furthermore, the dissolution of electrodes and the electrical energy consumption will also be attained. During the treatment process, it seems that beyond the electrocoagulation route, the electrooxidation of organic compounds is possibly to occur since the results appear to indicate the formation of by-products more recalcitrant than the parent substances.

The electrochemical alternative used in this research opens the possibility of integration with other techniques to improve the performance of the depuration systems.