Air
Air Air pollutants like volatile organic compounds (VOC's) and odours are well known.
But also off gases and flue gases are often polluted by particulates, aerosols, acid gases and various other noxious chemical substances that need to be removed before discharge into the atmosphere is possible or allowed.
Waterleau offers a wide range of solutions for air and gas treatment problems, based on knowhow acquired from MECS (Monsanto-EnviroChem Systems) and Socrematic. The centre of competence for air treatment is Waterleau France, a specialist team of experienced people which used to operate under the name Socrematic.
WATERLEAU France its main pollution control systems are :
1. | Chemical pollutants abatement | elimination of dust and fine droplets up to 0,3 µm |
2. | Industrial dust collection (wet) | removal of dust from off gases |
3. | Flue gas treatment | treatment of flue gas by wet and semi-wet processes, dry and semi-dry processes |
4. | VOC-treatment | recuperation processes and destruction of VOC's emitted by solvent using industries |
5. | Odour control | reduction of unpleasant odours coming from industrial activity, waste treatment, wastewater treatment plants, ... |
6. | Sterelec® electrochlorinator | production of chlorinated water |
Typical sources of VOCs and odour:
Waste Water Treatment
Composting
Food Processing
Paints/Coatings/Plastics
Chemicals and Petrochemicals
Pharmaceuticals
Typical VOCs:
alkanes: methane, hexane, decane; alkenes: ethylene, hexene
aromatics & polyaromatics: benzene, toluene, xylenes; aldehydes & ketones: acetaldehyde, formol butanal alcohols & acetates: ethanol, propanol, ethylacetate
organo-chlorinated HC chloroform, perchlor - ethylene, dichloromethane
sulfur containing components: H2S, CS2, COS, methanethiol, mercaptanes, dimethyldisulfide, dimethylsulfide
nitro-organics & ammonia: diethylamine, trimethylamine, pyridine, acetonitrile, acrylonitrile
When all source control methods have been used, it happens frequently that a residual pollution remains which can only be treated by end-of-pipe control methods. These exist in two groups: + Recovery: used when the VOC in question has a significant reclaim value and the cost to recover (including the value of the end product) is less than the alternative method. + Destruction: used when the concentration of VOC is low enough and/or the VOC has little or no value making recovery cost prohibitive. Waterleau is mainly active in the last category, within which one can again distinguish several systems: biological oxidation, thermal oxidation and chemical oxidation. In cases where the feasibility of solvent recovery is difficult, the technology section scheme may guide you to a suitable solution. The choice between biofiltration and thermal or catalytic oxidation depends on the concentration of the VOC or organic pollutants, containing S and/ or N.
Three categories of VOC destruction:
- Thermal oxidation: Most common method, in which energy is added to the organic to initiate oxidation, an exothermic process.
- Biological oxidation: This method uses biological organisms to oxidize or 'eat' the VOCs, consuming them as a food source. This method has been traditionally used for wastewater treatment, but in recent years has emerged as a viable air purification technology. Little or no energy needs to be added in the form of heat or radiation to support this process.
- Chemical oxidation: This process uses chemical reactants such as peroxide, ozone, or bleach to oxidize VOCs. Not normally used for common VOC applications due to the higher cost of chemical consumption, this method is very effective at controlling streams with dilute VOC concentrations, such as in odour control.
In all three cases destruction of the VOC is achieved through oxidation. The products of this reaction are CO2 and H2O, both harmless to the environment (other pro ducts will result when inorganics such as sulphur or halogens are present). There are many variations of oxidation systems, most of which fall under thermal oxidation.
