Acid scrubber in bakeries and the confectionery industry

Due to the use of many different fragrances and sweeteners, all kinds of odour components are often released around industrial process lines in the bakery and confectionery industry. Most aromatic and flavouring substances (very often esters) have a very specific strong pungent odour. Because they are already detectable at very low concentrations, air flows must first 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 react ester fouling from the air.

An acid air scrubber is therefore a very good technique to remove alkaline components from an air stream. By adding an acid, the pH of the washing water is lowered and the alkaline 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 most common. 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.