| With the development of intensive animal husbandry, odor emitted from animal husbandry not only affected the health and production performance of livestock, but also threatened the health of people. It has been considered to be second only to noise pollution, which is one of the six public nuisance. Biofilter deodorization is the most widely used means because it is a less cost, low energy consumption and high efficiency method.In this study, some bacteria and fungi agent was inoculated to the biofilter filling material, the removal of main odor emissions component (hydrogen sulfide and ammonia) was investigated in a lab scale biofilter filled with compost, perlite, earthworm cast and sawdust. The biofilter chamber was manufactured with PVC and was separated into 3 layers in order to keep filling material soft. Its diameter and height were 36cm and 120cm, respectively. Four treatment (A, B, C and D) was designed according to filling material in biofilter, and C/N for filling material was adjusted to 25-40 in all treatments with sawdust. The effect of moisture ( humidity) and pH value in filling material, air inlet volume load of hydrogen sulfide and ammonia on the removal efficiency were investigated in this paper. The result on Biofilter treatment was concluded as follows:1. The biofilter was run in a stable state during the experiment. The paramenters met the design requirement well because humidity and waste gas distribution within installations were controlled properly.2. The concentration of hydrogen sulfide and ammonia at inlet was 7.13mg/m3 -19.98mg/m3 and 12.67 mg/m3-14.35mg/m3, respectively. When the system was stable, the concentrations of H2S was 1.91mg/m3, 0.85 mg/m3, zero and 0.21mg/m3 in treatment A, B, C and D, that of NH3 was 3.31 mg/m3, 3.27 mg/m3, 0.93mg/m3, and 1.62mg/m3, respectively. The results showed that removal rate of H2S was 100% and the concentration of hydrogen sulfide emission met the first rank in corresponding standards at treatment C but hydrogen sulfide emission did not meet the emission standards at treatment A and B. The concentration of ammonia emission met the second rank at treatment C and D, but that met the third rank at treatment A and B.3. There was abundance microorganisms in filling material. The result showed that the number of bacteria was up to (2.23-3.26)×1010cfu/g and total number of fungi was up to (2.00-3.08)×105cfu/g at treatment C.4. With the height of biofilter increased the removal efficiency improved. When the height achieved 110cm, the removal rate was more than 95.23% for hydrogen sulfide, and 91.23% for ammonia .5. The nitrogen and sulfur distribution in filling material of biofilter were uneven. The content of ammonium nitrogen reduced from bottom to top; and nitrate nitrogen at bottom part was lower than the upper part at first, but with the extension of operating time, it became reversed. This showed that the microorganisms in filling material was layered, the different microorganisms occupied different spatial location, and decomposed different components in malodor.6. In the biofilter deodorization system, a few earthworms were alive in treatment C, all earthworms were dead in treatment A, B and D. This showed that inoculating earthworm could directly reveal the effect of noxious gas degradation in a biofilter. |
