The advanced oxidation processes - AOP - are oxidation processes that involve species with a high potential of oxidation, with a synergic action. A broader definition of these processes may be provided on account of their joint feature of generating and using highly reactive species of free radicals oOH, whose action can lead to the almost complete degradation of the resistant chemical compounds, until mineralisation. In the past years one has developed new processes of water purification by advanced oxidation processes, which, from the viewpoint of the mechanisms involved, may be divided into two large categories :
- a. abiotic degradation processes, such as : thermal degradation (combustion), the utilisation of melted salts, wet oxidation, chemical oxidation, acid-base hydrolysis, electrochemical oxidative processes ;
- b. processes involving a photodegradation mechanism, such as : photolysis in a H2O2/UV, O3/UV and O3/H2O2/UV system, photolysis in the presence of sunlight, homogeneous photocatalysis, photocatalysis at the interface of the nanostructured systems.
From the point of view of the practical applications, the advanced oxidation processes that involve the utilisation of ozone as a process partner are of particular interest, mainly due to their applications at the industrial scale. This kind of processes cover a various area, including the generation of the OHo radicals in the processes of decomposing O3 into aqueous solutions, catalytic ozonisation in the presence of the nanostructured adsorbing systems (O3/ADS), ozone-peroxide processes (O3/H2O2), ozone photolysis in an ultraviolet radiation field (O3/UV), heterogeneous photocatalysis.
The advanced oxidation processes developed by ICPE Bistriţa S.A. are mainly based on the utilisation of ozone within heterogeneous systems, including processes of ozonisation in an aqueous environment, in the presence of the adsorbing environments (O3/granular activated charcoal, O3/zeolites), processes of ozone photolysis in the presence of ultraviolet radiations (O3/UV), advanced oxidation processes in electrochemical cells in a medium frequency field, with or without the presence of ozone, electro-Fenton processes.