Acid scrubber in the pharmaceutical industry

The active ingredients in medicines can often have a very unpleasant taste or smell, which is why fragrances and flavourings are added in a high concentration. These types of solvents (usually esters) have a very specific strong pungent odour. Because they are already detectable at very low concentrations, air streams must be cleaned before they can be exhausted to the outside. Depending on whether an ester behaves acidic or alkaline, an acid air scrubber can be a good technical solution to remove ester contaminants from an air stream.

.By adding an acid, the pH of the washing water is lowered and the basic components react with the acid to form a salt. The dosing of the acid is done by means of a pH control, in most cases the pH value of the washing water varies between 3 and 6.

Depending on the salt formed, more or less washing water is discharged, this is measured on the basis of density and/or conductivity. The drainage can contain up to 15 % of salts and is discharged or evaporated for reuse.

Various acids can be added, sulphuric acid (H₂SO₄) and nitric acid (HNO₃) are used most commonly. For specific applications, e.g. to capture ammonia (NH₃), the acid then forms ammonium sulphate or ammonium nitrate, both salts can be used as fertiliser or soil improver. Because of their alkaline character, amines and esters (odour components) can also be captured in an acid scrubber.

In case of strongly acidic air flows with, for example, high concentrations of hydrochloric acid (HCl), the scrubber itself will become acidic. In this type of scrubber, the maximum acidity level must be regulated by draining or adding a base (alkaline scrubber). Combustion plants often use this type of wet scrubber.

The advantages of the acid scrubber are:

• Completely made of plastic to prevent corrosion
• Relatively compact
• Horizontal and vertical airflow possible
• Very high removal efficiency
• Can be built modular, multi-stage systems
• The formed salts can be reprocessed and reused

Air Solutions has experience with acid washers in the following industries:

• Manure processing (ammonia)
• Composting (ammonia)
• Waste treatment plant (ammonia, amines)
• Fertilizer production (ammonia)
• Pharmaceutical industry (esters)
• Chemical industry (esters)
• Foundries and fish feed production (amines)

Quality marks:

• ISO 9002
• CE
• KIWA
• VLAREM
• DVS welding certification