Nyex-a is Arvia’s technological solution where the chemical electro-oxidation process is used as a tertiary polishing treatment stage for industrial wastewater plant. Under these conditions, in order to enphatize the oxidizing capacity of the system, the electro-oxidation takes place in the presence of an absorbent medium. The lamellar electrodes that contain the Nyex absorbent material are packed inside a module that constitutes the discrete unit of the Ariva system. Depending on the type of application and the amount of pollutant that needs to be removed, multiple modules can be combined together to obtain the desired treatment capacity. The module is built in reinforced fiber glass, the reaction element is installed inside and the flow can pass through it from top to bottom or in the opposite direction, depending on the size and type of configuration chosen.
This technology is a very viable alternative, with very low operating costs, to more conventional processes, such as filtration on granular carbon or chemical precipitation, in which the regeneration procedure and the need to dispose the resulting sludge from the process represent the main costs of the treatment stage. It also represents an alternative to the use of ozone technology, which usually requires highly specialized personnel and high operating costs connected to the large electricity demand for the gas generation
With an incoming COD, usually not higher than 500 ppm, and a suspended solids concentration lower than 10 ppm, each module is capable of handling a flow rate up to 3 m3/h. Typically, to determine the performance level of the system, a laboratory study is conducted beforehand, in which a significant sample of the wastewater to be treated is subjected to chemical electro-oxidation and subsequently analyzed. Furthermore, to confirm the laboratory results, the technology can be tested directly on site by using one of the available pilot plants. A weak electric field applied between the electrodes that contain the filter media allows to oxidize the macromolecules adsorbed on its surface thanks to the activity of the hydroxyl radical OH– which can degrade them into H2O, O2 and CO2. At the same time, it regenerates the adsorbent material which can therefore be kept running without time limits and without the need to stop the system to remove and regenerate it.
A system composed of several Nyex-a units is usually used as a polishing stage in a waste water treatment plants serving the chemical, pharmaceutical, oil & gas, paper, textile and F&B industries with hydraulic flow rates ranging from 0.5 m3/h up to about 140 m3/h and reductions in influential COD in the range 500 ppm – 5 ppm.