Production of biodiesel utilized as a renewable energy is hampered by the problem of disposal of the strongly alkaline by-product crude glycerol. We examined simultaneous biogasification by adding crude glycerol to a methane fermentation process for food waste. We used a fermentation plant processing okar(a soy pulp).When food waste was added to this plant, the biogas production rate decreased from 2.4 ㎥/㎏-C to 1.3 ㎥/㎏-C because of the inhibition of fermentation by the food waste. However, when both food waste and crude glycerol were added to the plant, the biogas production rate recovered to 2.0 ㎥/㎏-C. Thus, simultaneous input of crude glycerol and food waste contributes to both the disposal of the strongly alkaline crude glycerol and the prevention of the fermentation inhibition by food waste. Use of biogas as an automobile fuel will reduce 0.45 tons of atmospheric CO₂ per year, thereby, contributing to low carbonization.

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In this study, research of optimal conditions for nitritation with immobilized nitrifying bacteria on hydrogels and identification of their bacterium which producing with speedy and alternatively only NO₂^- from 3,000 to 5,300 ㎎/L of NH₄-N was carried out. The fraction of biocatalysts was approximately 10 wt% in 4L of a bubbling vessel in a batch reaction. The amount of produced NO₂^- increased with rising pH(pH 7.0 to 8.0).At pH 8.0, 5,300 ㎎/L of NH₄-N completely disappeared, and 5,058 ㎎/L of NO₂-N was produced. From the result of gene analysis, it was suggested that this nitritation reaction without production of NO₃^- was caused by the bacteria Methylobacterium extorquens DM4, which acts as a nitrite-reducing enzyme. It is expected that high concentration NO₂^- obtained with high-speed biologic treatment can lead to the development of a new disappearance-type nitrogen eliminating system that is cheap and compact, followed by biologic treatment.

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