Department of Social and Environmental Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashihiroshima, Hiroshima 739-8527, Japan.
Water Res. 2010 Mar;44(5):1409-18. doi: 10.1016/j.watres.2009.11.021. Epub 2009 Nov 18.
Anaerobic wastewater treatment plants discharge dissolved methane, which is usually not recovered. To prevent emission of methane, which is a greenhouse gas, we utilized an encapsulated down-flow hanging sponge reactor as a post-treatment to biologically oxidize dissolved methane. Within 3 weeks after reactor start-up, methane removal efficiency of up to 95% was achieved with a methane removal rate of 0.8 kg COD m(-3) day(-1) at an HRT of 2 h. After increasing the methane-loading rate, the maximum methane removal rate reached 2.2 kg COD m(-3) day(-1) at an HRT of 0.5 h. On the other hand, only about 10% of influent ammonium was oxidized to nitrate during the first period, but as airflow was increased to 2.5 L day(-1), nitrification efficiency increased to approximately 70%. However, the ammonia oxidation rate then decreased with an increase in the methane-loading rate. These results indicate that methane oxidation occurred preferentially over ammonium oxidation in the reactor. Cloning of the 16S rRNA and pmoA genes as well as phylogenetic and T-RFLP analyses revealed that type I methanotrophs were the dominant methane oxidizers, whereas type II methanotrophs were detected only in minor portion of the reactor.
厌氧污水处理厂排放溶解甲烷，通常不会回收。为了防止温室气体甲烷的排放，我们利用封装的下流式悬挂式海绵反应器作为后处理，以生物氧化溶解的甲烷。在反应器启动后 3 周内，在 HRT 为 2 h 的条件下，甲烷去除率高达 95%，甲烷去除率为 0.8 kg COD m(-3) day(-1)。在提高甲烷负荷率后，在 HRT 为 0.5 h 的条件下，最大甲烷去除率达到 2.2 kg COD m(-3) day(-1)。另一方面，在第一个阶段，只有约 10%的进水氨被氧化为硝酸盐，但当空气流量增加到 2.5 L day(-1)时，硝化效率增加到约 70%。然而，随着甲烷负荷率的增加，氨氧化速率随后下降。这些结果表明，在反应器中，甲烷氧化优先于铵氧化。16S rRNA 和 pmoA 基因的克隆以及系统发育和 T-RFLP 分析表明，I 型甲烷氧化菌是主要的甲烷氧化菌，而 II 型甲烷氧化菌仅在反应器的一小部分中检测到。
