A FIELD-SCALE EVALUATION OF COMPOST BIOFILTRATION OF AMMONIA VOLATILIZED FROM SWINE MANURE COMPOSTING IN A FORCED-AERATION SYSTEM

摘要

Large amounts of organic nitrogenous compounds in animal manure are easily mineralized to produce ammonia in the composting process. This field-scale study evaluated the elimination effects of a compost biofilter on ammonia emitted from swine manure composting using a facility featuring four fermentation compartments (5.00 m L x 3.92 m W each) and one biofiltration compartment (5.00 m L x 3.92 m W). The mixtures of swine manure and chopped corn stalks were transported and fermented in each of the four fermentation compartments successively. Odorous gases emitted from the composting piles were collected and supplied to the biofilter (3.80 m L x 1.83 m W x 1.00 m H; mature compost media). Results showed that 16.0% of the total initial nitrogen of the composting mixtures was emitted in the form of ammonia, and ammonia emission was positively correlated with temperature inside the composting piles. During the four-week composting period, the compost biofilter could remove 97.6% +/- 3.2% (mean +/- SD based on daily values) of the ammonia for loading rates ranging from 0.03 to 0.23 kg NH3 m(-3) biofilter h(-1) at a constant empty bed retention time (EBRT) of 101 s. Ammonia elimination efficiency during the first, second, third, and fourth composting week was 94.7% +/- 5.1%, 98.1% +/- 1.6%, 98.7% +/- 0.4%, and 99.1% +/- 0.2%, respectively. Nitrogen content of the biofilter media increased by 9.1% after the four-week operation. Therefore, use of mature compost as biofilter media offers the benefits of reduced material cost and increased fertilizer value of the compost while markedly mitigating emissions of odorous gases (especially ammonia) to the environment.