Multi-pollutant Scrubbers for Removal of Ammonia, Odor, and Particulate Matter from Animal House Exhaust Air

Reprinted, with permission, from the proceedings of: Mitigating Air Emissions From Animal Feeding Operations Conference.

The proceedings, “Mitigating Air Emissions from Animal Feeding Operations”, with expanded versions of these summaries can be purchased through the Midwest Plan Service.

This Technology is Applicable To:

Species: Swine, Poultry
Use Area: Animal Housing
Technology Category: Scrubber
Air Mitigated Pollutants: Ammonia, Odor, Particulate Matter

System Summary

In The Netherlands, Germany and Denmark packed-bed biotrickling filters and acid scrubbers for removal of ammonia from exhaust air of animal houses are off-the-shelf techniques for ammonia removal (70 – 95% average removal). At the moment a new generation of so-called “multi-pollutant scrubbers” is being developed and tested that not only removes ammonia but also aims for significant removal of odor and particulate matter (PM10 and PM2.5) from the air. Recently a 3-year research program has started that monitors and aims to improve the performance of five farm-scale multi-pollutant scrubber from different manufacturers. The preliminary results show that the average ammonia removal is relatively high (83%, n = 7) but that the average removal of odor (40%, n = 8) and particulate matter (PM10: 43%, n = 2; PM2.5: 42%, n = 2) needs to be improved further.

Applicability and Mitigating Mechanism

  • Ammonia scrubbers consist of two types: either acid scrubbers or biotrickling filters
  • Multi-pollutant air scrubbers usually consist of two or more scrubbing stages where subsequent removal of coarse dust, ammonia and odor takes place
  • Scrubber are mainly applied in pig housings with central ventilation ducts; application in poultry housings are scarce because of high dust concentrations
  • Already 10% of all exhaust air from pig houses The Netherlands is treated; this equals a treatment capacity of 79 million m3/hour


  • Odor and dust removal is less effective than ammonia removal, at least for now
  • High concentrations of coarse dust result in blockage of packing material and increased energy use (pressure drop)
  • Costs are considered high, but multi-pollutant scrubbers provide an option for large scale livestock operations to remain in operation in areas nearby residential areas and sensitive ecosystems


Investment and operational cost of scrubbers for newly built production facilities in € / animal space.
Acid Scrubber Biotrickling Filter Multi-pollutant scrubber (3-stage water/acid/biotrickling)
Investment Costs 32.8 43.5 50.3
Operational Costs (year^1):
Depreciation (10%) 2.6 3.4 4.2
Maintenance (3%) 1.5 1.8 2.0
Interest (6%) 0.8 1.0 1.2
Electricity use ((€ 0.11 kWh^-1) 3.3 3.8 3.7
Water use (€ 1.0 m^-3) 0.6 1.7 0.6
Chemical use (€ 0.6 L^-1 H2SO4, 98%) 1.4 n/a 0.7
Water discharge [b 0.6 2.5 1.0
Total operational costs (year^-1) 10.8 14.3 13.5

[a] The investment costs are based on a maximum ventilation capacity of 60 m3 animal place-1 h-1.
[b] Water disposal costs are assumed of € 10/m3 for discharge from acid scrubbing and € 2/m3 for discharge from biotrickling or water scrubbing. For the multi-pollutant scrubber, discharge water from the biotrickling or water scrubbing step is reused in the acid scrubbing step. The systems do not include a denitrification unit which might significantly decrease water discharge costs.
[c] n/a = not applicable.


Roland W. Melse, Nico W.M. Ogink, Bert J.J. Bosma; Animal Sciences Group, Wageningen University and Research centre, The Netherlands
Point of Contact:
Roland W. Melse,

The information provided here was developed for the conference Mitigating Air Emissions From Animal Feeding Operations Conference held in May 2008. To obtain updates, readers are encouraged to contact the author.