Process for washing treatment for purifying ammonia-containing air

Method for subjecting ammonia-containing air to be cleaned from a space to a washing treatment, using a filter unit comprising a filter matrix (225) which is capable of being run through by liquid in a first direction and permeable to gas in a second direction transversely to the first direction;

• wherein
• an aqueous liquid is introduced at a relatively high point on the filter matrix (225) of the filter unit,
• the ammonia-containing air to be cleaned is passed through the filter matrix (225) in the second direction, and
• the aqueous liquid enriched with ammonia is collected at a relatively low point, characterized in that the filter unit comprises at least one cloth (226′, 226″) and the ammonia-containing air to be cleaned downstream of the filter matrix (225) is passed through at least one cloth (226′, 226″), wherein the at least one cloth (226′, 226″) is in liquid-exchanging contact with the filter matrix (225).