(Invited) Electro-Separation Combined with Electro-Conversion for Wastewater Treatment and Recovery: Case Study of Electro-Precipitation or Electro-Sorption Combined with Advanced Electro-Oxidation

Abstract

The water stress combined with an increase of water demand lead to a worldwide water crisis that is urgent to solve. The United Nation has established sustainable development goals to deal with this challenge. In the meantime, raw materials resources are decreasing, drastically for some of them. Thus, 30 critical raw materials (e.g., rare earth elements, phosphorus, magnesium) have been listed by the European Union in 2020. The reuse of treated wastewater remains one of the most effective solution, while the concomitant recovery of value-added compounds is gaining increasing interest.To answer this issue, advanced physico-chemical treatments need to be developed in order to separate the value-added compounds from the solution, while the non-valuable biorecalcitrant pollutants must be eliminated. Electrochemical systems are arising importance. Their heterogeneous nature can involve electro-catalysis through the development of innovative multi-functional materials, which is a further step towards the rise of greener processes by avoiding chemicals addition. Electro-separation technologies are able to selectively isolate compounds according particularly to their electrophoretic mobility, the applied current & electrode potential, the electrode materials properties and the electrolyte characteristics. They can be competitive by increasing the selectivity of separation. In the meantime, electro-conversion systems are able to mineralize recalcitrant organic pollutants from wastewater, while value-added organic compounds can be obtained by electro-synthesis. Therefore, the coupling between electro-separation and electro-conversion systems seems promising to solve water issues.In this talk, two case studies will be presented, one about the electro-precipitation in combination with advanced electro-oxidation and the second case about electro-sorption coupled with advanced electro-oxidation. In the first study, the possibility to recover phosphate, while eliminating tylosin as representative pharmaceutical pollutant will be presented. In the second work, the recovery of phenolic compounds from olive mill wastewater will be exposed, considering the subsequent elimination of residual organic pollutants from the effluent. Emphasis will be given on engineering (e.g., reactor design) and modeling aspects.