Air Scrubbing Techniques for Ammonia and Odor Reduction at Livestock Operations: Review of On-farm Research in the Netherlands

Acid scrubbers and biotrickling filters have been developed for ammonia (NH3) removal at pig and poultry houses in The Netherlands over the last 20 years to prevent acidification and eutrophication of soils. Because of growing suburbanization, odor removal is increasingly considered important as well. In this review, we report the results of the on-farm research on full-scale operated scrubbers for treatment of exhaust air from animal houses with regard to NH3 and odor removal in The Netherlands. The NH3 removal of acid scrubbers ranged from 40% to 100% with an overall average of 96%. The NH3 removal of biotrickling filters ranged from −8% to +100% with an overall average of 70%. Minimum empty bed air residence times (EBRTs) were 0.4 to 1.1 s. For acid scrubbers, process control with pH measurement and automatic water discharge is sufficient to guarantee sufficient NH3 removal. For biotrickling filters, however, improvement of process control is necessary to guarantee sufficient NH3 removal. The odor removal of acid scrubbers ranged from 3% to 51% with an overall average of 27%. The odor removal of biotrickling filters ranged from −29% to +87% with an overall average of 51%. Minimum EBRTs were 0.5 to 2.3 s. Further research is necessary to explain this variation and to improve the odor removal efficiency of both acid scrubbers and biotrickling filters.