Biogas usually contains CH4 and CO2 as main components with the ratio of 6 : 4, and its composition varies with wide range depending on digester conditions. In addition to concentration change of each constituent, biogas composition could be changed due to the variations in the organic matter treatment process. The aim of the study is to analyze the production and application to a microturbine system of CH4/N2 rich biogas produced from Gong-Ju wastewater
treatment plant. CH4/N2 rich biogas is produced due to the internal wastewater recirculation. The internal wastewater recirculation is intended to enhance NO3- removal without additional carbon source input. As a result, the digester was shown to be the highest contributor for nitrogen removal and average CH4 concentration was lowered compared to the typical biogas composition. Nitrate removal rate was influenced by the internal recirculation ratio. Content of N2
has no effect on biogas clean-up system performance. Besides, adaptability of CH4/N2 rich biogas to microturbine was satisfactory with very low NOx and SO2 concentration in microturbine exhaust gas. Influence of high N2 concentration of biogas on NOx concentration was limited due to the low combustion temperature.
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