Oxidative electrochemical processes are characterised by versatility, environmental compatibility and high effectiveness, and have a continuously growing importance both in selective organic synthesis and in degradation of organic pollutants.
For the oxidative degradation of organics in wastewater treatment, the aim may be the complete mineralisation of the pollutants or the conversion of the toxic organics to biocompatible compounds. The proposed technology consists of the electrochemical treatment of wastewater using an undivided filter press reactor in which the anodic material is characterised by a high overpotential for oxygen evolution, such as boron-doped diamond. These anodic materials can generate hydroxyl radicals and other oxidising species, such as ozone and hydrogen peroxide, which can mineralise the organic pollutants or convert the toxic substances to biodegradable compounds.
The technology was tested at lab scale for different applications, achieving the requested performances, depending on reactor design and operative conditions.
Good results were obtained in the treatment of agro-industry wastewater (in particular olive oil mill wastewaters), characterised by high organic load and presence of such biodegradable substances as sugars or proteins, along with a toxic fraction constituted by phenolic compounds. The treatment allowed decreasing the toxicity of the waste through selective removal of phenols and cyclic intermediates.
The application of electrochemical treatment for micro-pollutants removal from wastewater was also successfully tested. Degradation of such different substances as pesticides, surfactants and organic hydrocarbons down to a few ppb was achieved.
The process was also applied to disinfection and purification of water: mineralisation of trace pollutants was almost complete, whereas the population of bacteria (namely Escherichia coli, Enterococcus faecalis and a mixture of the coliforms Acinectobacter and Enterobacter) was appreciably reduced.

Innovative Aspects:
The electrochemical technology proposed is based on the generation of OH radicals, which are the key oxidant that controls most Advanced Oxidation Processes (AOPs), such as ozonisation, photocatalysis and Fenton process. The field of application of this technology is then the same as the other advanced oxidation processes: treatment of wastewater containing bio-refractory organic compounds, micro-pollutants removal from surface or ground water, disinfection and purification of drinking water.
With respect to most of the other AOPs the proposed technology does not require chemicals, avoiding the risk of transport and storage of hazardous substances.
Moreover, electrochemical technology is characterised by high controllability of the OH production, which allows utilising this process in a wide range of applications. The electrochemical technology presents different advantages such as the versatility of the process and the simplicity of the reactors in terms of construction and management, which makes them particularly suitable for automation. The electrochemical processes are high intensive: the small size of the electrochemical units allows realising a mobile wastewater treatment unit for water reclamation and reuse.

 

Patents/Rights: Secret know-how

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