GAS SCRUBBERS
Gas scrubbing consists of solubilising a gaseous pollutant in a liquid. This liquid can be either water or water with reageants or solvents. There are three different types of gas scrubbers that we manufacture; random packing scrubbers; spray gas scrubbers and venturi scrubbers. The choice of which type to be used depends on the characteristics of the gas to be removed.

With hydrogen sulphide and mercaptans being the major odour source on a sewage treatment works, we usually offer a combined chemical scrubbing tower dosing with sodium hypochlorite and caustic soda. We will also offer a first stage scrubber if ammonia is likely to be present using sulphuric acid as the reagent. We can offer all other permutations including biofilters and carbon polishing and the design is assessed on a project specific basis.

BIO FILTRATION
Biological treatment is used increasingly for the removal of odours. Biological abatement systems operate by the dispersion of the contaminated gas through medium supporting specific micro-organisms that decompose the odorous compounds and use them as a foodstuff. In a biofilter the polluted gas passes through a porous media on which the bacteria are set. A range of different types of media’s are used depending upon the application.

The residence time of the compounds determines how long the micro-organisms have at their disposal to decompose the compounds and we design our biofilters to ensure optimum contact time while considering cost efficiency.

Often it is more cost effective to have a slightly faster contact time, but combined with a carbon polishing filter. Biofilters are particularly suited to odour removal in sewage treatment works where there are constant contaminant loads. They are also often used in many industries for VOC removal. Europe Environnement uses an incompressible filter media with a low pressure drop. This allows us to design and fabricate tall filters with a reduced footprint area.

Biological filters offer substantial benefits in particular whole life costs are advantageous.

ACTIVATED CARBON ADSORPTION
The principle of adsorption is based on trapping the gaseous pollutants on the surface of a porous solid. Chemical impregnation is used to increase significantly the performance efficiency and adsorption capacity of activated carbon. Activated carbon technology is ideal for intermittent level loads and most malodours, including solvents and VOC’s. When a carbon bed is saturated with contaminant the material is normally removed and exchanged for new material and the exhausted carbon is either disposed of or reactivated by the carbon supplier. This technology is often used in combination with chemical scrubbers and biofilters to polish the air where stringent odour discharge levels are specified.

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