Photooxidation Technology for Exhaust Air and Wastewater Treatment
Industrial companies and municipalities that are planning or already operating a cleaning system to reduce pollutants have a number of requirements for the technology to be used. In addition to the lowest possible investment and operating costs, this should be characterized by a small space requirement and high operational stability. Flexible possibilities for adapting to the operating conditions with regard to future production-integrated emission reductions or capacity expansions are further desired advantages. uviblox FOX technology stands for innovative photooxidation for the treatment and purification of exhaust air and wastewater streams.
The advantages of the procedure:
- Simple process control and low technical effort
- Safe compliance with guidelines and limit values
- High economic efficiency due to low operating and investment costs
- Low space requirements
- Easy handling and low personnel costs
- Operational reliability and high system availability
Photo-oxidation is an oxidation reaction triggered by light. UV light consists of electromagnetic waves, the energy content of which depends on the wavelength. The shorter the wavelength, the more energetic the radiation is.
A typical UV radiation source emits different wavelengths. If a pollutant molecule is to be cleaved directly by a radical chain reaction by means of UV radiation, then the binding energy of this molecule must ideally coincide with the energy of the photons emitted by the emitter. This reaction process is called photolysis.
These dissociation energies are known for almost all compounds and functional groups and are determined by the chemical bond types involved in the molecule.
In addition to photolysis, other effects can be used for pollutant degradation.
If radiation (H) is emitted by the UV emitter in the range of 185nm, these photons can dissociate oxygen. The atomic oxygen formed can form ozone (O3) by reaction with other oxygen molecules from the ambient air or oxidize a pollutant molecule (R-R) directly and thus enhance the photolysis process. Existing water (H2O) is also split by photons into hydroxyl radicals (OH), which also participate in the oxidation reaction with the pollutants.
The reactions triggered by this then proceed to complete oxidation if the irradiation time is long enough.
The principle of Direct Photo-oxidation (DF)
The broad spectrum of action of photo-oxidation in the removal of pollutants from gaseous or fluid media is based on the innovative and patented processes developed by us.
Procedural scheme
Cleaning of the volume flow
In the field of exhaust air purification, the main stream loaded with VOC (volatile organic compounds) is first conducted via a coarse- or fine-filtration stage and, if necessary, via a droplet separator stage, depending on the air quality.
UV photo-oxidation
The air stream then flows through the UV reactor, which is equipped with low-pressure or medium-pressure UV lamps, depending on the application. Here, the pollutants are oxidized and, ideally, completely separated into carbon dioxide (CO2) and water (H2O).
Catalyst
For optimization, a catalyst stage can be connected downstream in the absence of catalyst poisons. In many cases, however, at least one stage is provided for the destruction of excess ozone.
The principle of Regenerative Photo-Oxidation (RF)
Procedural scheme
Purification by adsorption
The VOC-loaded exhaust air flow is alternately conducted via two parallel adsorption stages. In this case, the fluctuating VOC loads with high or low pollutant concentrations are completely separated from the necessary emission limit values by adsorption using a suitable adsorbent. The outgoing exhaust air permanently meets the required clean air limit values.
Regeneration cycle
Even before the adsorbent is exhausted, a switch is made to the second, parallel, fresh adsorption stage. The first stage passes into a UV operating phase in the regeneration circuit. In this case, the circulating air is passed through a UV stage and then through a catalyst stage before it returns to the adsorption stage.
Energy efficiency through synergy
As a result of the energy input from the UV radiation, the circulating air heats up to operating temperatures, which are necessary for the desorption and regeneration of the adsorbent as well as for the operation of the catalyst stage.
UV photooxidation
The previously adsorbed organic pollutants are expelled quickly and uniformly from the adsorption stage under controlled conditions and fed into the UV photooxidation stage with subsequent catalysis via the circulating exhaust air stream.Here, the photooxidative degradation of the pollutants up to CO2 and H2O takes place.
Scalability
The system can be expanded and retrofitted modularly in the event of production-related growing volume flows or increasing pollutant concentrations.