Deodorization of composting shed by a bubbling system using sulfuric acid solution
2006
Itoh, H.(Gifu-ken. Livestock Research Inst., Takayama (Japan)) | Taguti, Y. | Itoh, H. | Imaeda, N. | Otani, T.
We developed a deodorization system to remove ammonia gas from composting shed. The system was used for the composting shed of the Swine Research Department, Livestock Research Institute in Gifu Prefecture. The shed was covered with vinyl-film, the air away from which was collected with a blower from the duct at the uppermost cover and blew into 78% sulfuric acid in the bubbling tank (500L) of the system, 3cm below the solution surface. We measured ammonia, methyl mercaptan, dimethyl sulfide and dimethyl disulfide in the inlet and outlet airs of the system to determine its effectiveness. Furthermore, we measured pH, EC, nitrogen and density of the tank solution saturated with ammonia (waste-solution). 1. The sulfuric acid solution in 60kg (an amount used for one examination) was saturated with ammonia on the 34th day, on average, after starting to use it. 2. The system ran with a constant capacity to deal with the air unless the acid solution was saturated, although the solution varied in amount. The ammonia gas content in the inlet air varied depending on fermentation stage of compost giving a mean of 1 68 ppm, and that in the outlet air was 8 ppm. Thus, the average removal rate of ammonia gas was 95.4%. 3. The system showed little or no effect in removing methyl mercaptan, dimethyl sulfide and dimethyl disulfide. 4. The waste-solution was at 7.5 of pH and contained nitrogen of 88 g/L, providing a potential liquid fertilizer. 5. The total amount of nitrogen collected from the tank waste-solution was not incomparable with that estimated from ammonia required to neutralize 60 kg of 78% sulfuric acid (13,400g).
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