Odorless composting of the organic waste which served as disposal of waste edible fat and oil

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During the high-rate composting of organic materials containing waste edible fat and oil, the emission of ammonia gas was drastically reduced when they were degraded vigorously. The material balance of nitrogen was examined in the composting in detail, and it was found out that the reduction of the ammonia gas emission was not due to the neutralization of ammonia gas by the degradation intermediates of fat and oil, i.e. fatty acid, and owed to the uptake of nitrogen by microorganisms for enumeration of their microbial cells. Moreover, the cell density of fat and oil degrading microorganisms were counted on the LBTR agar medium containing tributyrin, and these microorganisms increased after the middle stages of composting, that corresponded well to the composting time when ammonia gas emission began to be reduced clearly. Two thermophilic bacteria, strains LT1 and LT4, with high degradation activity of tributyrin were isolated on the LBTR agar plate and then identified. In addition, the bacterium DOM-1 which itself does not have the ability to degrade fat and oil, but contributed to the degradation of them by cooperating with the bacterial strains LT1 and LT4 was determined by the microbial community analysis with the PCR-DGGE method. The DOM-1 was identified from DNA sequence of the band excreted from the gel.The compost product which contains high cell density of fat and oil degrading microorganisms were used as a seeding material for the next composting by mixing it to the composting raw material, it was confirmed that the seeding was effective for reduction of ammonia gas emission and the acceleration of fat degradation, moreover these effect appeared immediately after the start of composting. In addition, it was ascertained that the effect of the ammonia gas reduction was not limited to the case using edible fat and oil, but, hexadecane, one representative of mineral oils also was effective.