Biofiltration of odour and ammonia from a pig unit - a pilot-scale study

摘要

A pilot-scale biofiltration unit was constructed at a pig finishing building on the University College Dublin research farm. The biofiltration system was investigated over three trial periods. Exhaust air from a single pen was extracted by a variable speed centrifugal fan and passed through a humidifier and biofilter. A 0.5 m depth of woodchips of over 20 mm screen size was used as the biofilter medium. The moisture content of the medium was maintained at 64 +/- 4% (wet weight basis) for trial one and 69 +/- 4% (wet weight basis) for trials two and three using a load cell method. The volumetric loading rate varied from 769 to 1898 m(3) [air] m(-3) [medium] h(-1) during the three trial periods. Odour and ammonia removal efficiencies ranged from 77 to 95% and 54 to 93%, respectively. The pH of the biofilter leachate remained between 6 and 8 throughout the experimental periods. The pressure drop across the biofilter ranged from 14 to 64 Pa. It is concluded that a wood chip media particle size > 20 mm is suitable for use in biofiltration systems on intensive pig production facilities. This will minimize the pressure drop on the system fans to reduce overall operation costs. It is recommended that a filter bed moisture content (wet weight basis) of greater than 63% be used to maintain overall efficiency. An efficient air moisturizing system (humidification and bed sprinkling) along with a properly designed air distribution system must be incorporated in the overall design when operating at such high volumetric loading rates.