| Title |
A study on Characteristics of Nitrogen Removal by Mixed Culture of Methanotrophs |
| Authors |
이희자(Hee Ja Lee),안승구(Seoung Koo Ahn) |
| Abstract |
In this study, methane-oxidizing bacteria were isolated from a landfill cover soil and cultured in inorganic nutrient medium with methane as a carbon and energy source. The methane oxidation rate on O₂/CH₄ ratio and other important factors affecting the growth of methanotrophs were evaluated by batch cultures. Also, the possibility of aerobic denitrification by mixed culture of methanotrophs, NH₃ and NO₃^- removal rate on nitrogen concentration were investigated. The results of the study showed that methane-oxidizing bacteria were short rod and gram negative, and formed pink colonies. The settleability of the sludge was very good When O₂/CH₄ volume ratio were 1.8, 2.2 and 5.4, methane was oxidized in a first-order reaction with respect to the concentration of methane and rate coefficients of the reactions were 0.7, 0.9 and 1.1, methane was oxidized in a second-order reaction. Methanotrophs could tolerate pH fluctuations of influent, and the maximum denitrification rate and cell yield at pH 7.5 was 16.4㎎ NO₃^- -N/g VSS·hr and 12.2㎏ VSS/㎏ NO₃^- -N, respectively. The maximum specific growth rate of the methanotrophs was 0.3/day at 30℃, and the maximum denitrification rate was 35㎎ NO₃^- -N/g VSS·hr at 35℃. At a Cu variation of 0-30ppm, the growth rate of methanotrophs was highest at 1ppm. At an O₂/CH₄ volume ratio of 1.3, at which the growth rate was highest, and the maximum denitrification rate was 45㎎ NO₃^- -N/g VSS·hr. In the aerobic condition with DO concentration of 1.2㎎/L, denitrification rate was increased in porportion to nitrate concentration, Vmax and Ks were 3.5㎎ NO₃^- -N/g VSS·hr, 145㎎ NO₃-N/L, respectively. |