Odor Emission Control and Nitrogen Recycling by Using Adsorption Treatment at the Pilot Scale Composting Facility

The odors emitted during the first two weeks of composting were conveyed into replicated adsorption reactors (3.8m x 7.2m), loaded with finished compost, to remove odors at a pilot scale composting facility. The initial composting material (50 m3) consisted of dairy cattle manure and sawdust. Finished compost of the same volume filled the adsorption reactors. The ammonia concentrations of the exhaust air from the adsorption reactors averaged 17.2 ppm for the first reactor and 7.8 ppm for the second reactor, and the reduction rates were 91.6% and 96.4%, respectively. Adsorption treatment using finished compost is effective in eliminating sulfur compounds, and the reduction rates ware ranged from 72.8% to 100%. The reduction rates for i-valeric acid showed positive values (56-64%), although the rates for the other volatile fatty acids showed negative values. After the treatment, the adsorbent contained great number of ammonium nitrogen, and was nitrified 81-88% within three day by keeping the adsorbent in aerobic conditions. Total ammonia emission during the thermophilic stage was measured at 787g/t, and 768g/t of ammonia was trapped by the finished compost in winter. Therefore, the ammonia emission during the thermophilic stage was reduced 97.6% by using the adsorption system.