This type of biofilter is very interesting, simple, effective and economical (0,28 US$ per piglet produced for construction and operation costs considering a facility of 700 sow that produces weaned piglets). More design and operation information is needed and further research will try to determine:
– the relationship of the pressure differential vs. the air flow for various depths and biofilter material;
– the minimum exhaust air contact time to the filter medium required to obtain adequate odor reduction for various livestock species;
– practical dust removal techniques for the exhaust air to prevent biofilter clogging;
– practical moisture application system for the biofilter and the proper management of this system to apply and control moisture in the filter bed.

See Zeisig and Munchen, 1988