Studies On The Characteristics Of Ammonia And Hydrogen Sulfide Volatilization During Composting Of Pig Manure And Screening Of Deodorizing Microorganisms

Nowadays, great amounts of animal dung are produced, which have greatly polluted our country's ecological environment. Aerobic composting is an efificient way of dung disposal, which could turn organic solid waste to innocuous resources. To the pHenomenon of massive offensive odors volatilization and nitrogen loss seriously, we studied the characteristics of odor gas emission during pig manure composting and effects of related factors, and the method of bio-deodorization was ascertained as our research direction. For getting highly-efficient deodorization microorganisms, in this study, various microorganisms were isolated and purified from animal manure, garbage,soil, compost and so on, among which deodorization strains were selected. The results are as follows:1. By determination, we found odor gases emission was mainly at mesopHilic and earlier thermopHilic pHases during aerobic composting of swine manure. The quantity of NH₃ emission rose quickly in initial stages of composting, reached to the top at 4th day (63.87mg/m³), and then descended. The accumulative quantity of NH₃ emission before the 19th day was 84.21% of total NH3 emission. The quantity of H₂S emission at the first day was maximal (0.058mg/m³), then fell rapidly, which could not be detected at 13th day ultimately. Consequently, the earlier pHase is a well period to control odor gas volatilization.2. Analysing change curves of NH₃ emission , temperature, moisture content, pH value and water soluble NH₄⁺-N content during composting, we found the quantity of NH₃ emission was high in the condition of high temperature, having positive correlations with pH value, as well as water soluble NH₄⁺-N content which was the direct course of NH₃ emission.3. A selective medium was designed, by which we successfully selected out 41 strains that could directly utilize NH₃. These strains include 24 bacterias, 3 fungi, 9 actinomyces and 5 yeasts.4. The second screen was performed on 41 strains, among which we found B4 7.13 strain had a better deodourizing capability. Compared with control, B4 7.13 strain could reduce 85.721% of H₂S emission. Therefore, this strain was identified as StapHylococcus sciuri.