The pig farms continue to grow and more and more pigs are kept in the metropolitan areas. In order to effectively reduce emissions from pig stalls and for the approval of stable systems, the authorities are increasingly making effective exhaust air cleaning a requirement.

The entire exhaust air is bundled by a central exhaust air duct and blown through an exhaust air scrubber to reduce ammonia, dust and odor. The Möller company has a cooperation with the Dorset company from the Netherlands. The Dorset company has a single-stage, biological scrubber with the "Dorset trickle bed filter" exhaust air purification system that can separate dust, ammonia and odor from the air in the barn when pigs are kept without litter.

Exhaust air quantities from 8,000 to 500,000 m³ / h exhaust air can be cleaned. The principle is based on the contact of the substances contained in the exhaust air with microorganisms. These are settled in pH-neutral washing water, which is circulated, and in the packing.

In front of the exhaust air washer, the air is deflected downwards by 90 ° and a first pre-humidification takes place, whereby the first coarse dust particles are separated out. After the air has been redirected twice by 90 °, the air flows through the actual filter package, which is permanently sprinkled with circulating water, from bottom to top. Due to its pack form, the filter package has a large specific surface area on which the desired microorganisms can settle. The water-soluble ammonia is now washed out of the exhaust air into the circulating water by nitrifying bacteria and oxidized to nitrite and nitrate.



The water, which is enriched with dust, nitrite and nitrate, must be replaced regularly to avoid salt accumulation. The exchange can only take place in partial quantities several times a day or the entire drainage water can be renewed once a day.