Biofilters - the influence of different filter materials and different operating conditions on the reduction efficiency

A series of biofilter materials were tested for performance efficiency in t reating ventilation air from pig sheds. Two different phases were conducted . In phase A five different biofilter materials were tested with the aim of selecting the best material regarding the odor reduction and over all effi ciency. In conclusion of phase A, biochips, a new filter material, was sele cted due to its high average odor reduction (81%) in combination with a ver y low flow resistance (less than 30 Pa for filter volume loads of 600 m(3) h(-1) m(-3)). in phase B, biochips and coconut fiber peat were tested under different operating conditions. Biofilters number 3 and 4 each with down-f low air supply could realize a higher average odor reduction than biofilter 5 with upflow air supply. All three filter materials had the same moisture , however the two biofilters with down-flow air supply showed a more homoge nous moisture distribution but they also used approximately three times mor e water than biofilter 5. Like in phase A the specific odor cleaning effici ency was mainly influenced by the specific odor loading rate and showed onl y slight differences between the five biofilters differing in bulk layer he ight (0.5 m and 1.0 m) and air supply mode. All in all the investigation sh owed that the efficiency of biofilters can be optimized by using an new fil ter material and a appropiate operating mode.