Efficiency of sewage sludge and garden waste compost as biofilter for removal of ammonia in ventilation air from animal farms
Poulsen, T.G., Aalborg University, Denmark
(free)
Two types of composts made from either sewage sludge or from park and garden waste were compared with respect to their
efficiency as biofilter material for removing ammonia from air. Ammonia removal efficiency was investigated using both small
scale laboratory experiments and large scale experiments at a pig farm. Laboratory experiments were carried out using 30
cm high colums with a volume of 250 cm3 supplied with an artificial ammonia-air mixture whereas 1 m columns with a volume
of 27 liters supplied with the ambient air from inside the pig stable was used in the large scale experiments. Ammonia removal
efficiency from the air passing through the filters was more than 95% for both compost at both small and large scale
regardless of the air flow rates applied to the columns. Ammonia concentration profiles inside the compost columns measured
at the end of the experiments indicated that sewage sludge compost removes ammonia at significantly higher specific rates
than garden waste compost. The likely explanation is that sewage sludge compost contains higher numbers of nitrifying
bacteria originating from the wastewater treatment process.
KEY WORDS
Compost, sewage sludge, garden waste, biofilter, ammonia, air cleaning
