Development of Advanced Treatment Systems of Rural Sewerage by the Combination of Biogeofilter and Biotope Pond

通过对秋田市农村污水深度处理适宜植物的筛选，明确了夏季植物（牧草稻、田菁、意大利黑麦草）和秋冬植物（野菜、野泽）具有较高的氮磷吸收能力。我们在一个农村污水处理厂进行了生物地理过滤器（BGF）对农村污水的深度处理实验。在沸石填充的BGF中，2004年由于沸石吸收了大部分营养，饲料水稻植株生长非常糟糕，但2005年其生长和磷的去除率有所提高。将平均NH_4-N浓度为33mg/L的二次处理水以1天半的时间间隔提供给BGF，在2年的时间内，充装沸石几乎完全去除了NH_4-N。我们还为小学生环境教育构建了三个系列的BGF。我们在这些BGF中种植了花卉、蔬菜和田菁、纸莎草等资源植物。在生物群落池塘中，我们从周围的稻田中引入了鳉鱼和泥鳅，并观察了它们的生长情况。我们观察到池塘的生物多样性得到了保持。在种植植物，观察生长和学生的最后展示后，我们明确了孩子们的环保意识得到了激发，老师对这次实验的评价很高。这些研究表明，为了有效地对农村污水进行深度处理，必须考虑滤料与植物的营养吸收能力，形成合适的组合模式，以达到处理后水质的目标。

As a result of the selection of plants suitable for the advanced treatment of rural sewerage located in Akita City, we clarified that summer plants including forage rice plant, sesbania, Italian rye grass, and fall-winter plants including potherb mustard and nozawana have high nitrogen and phosphorus absorbing ability. And we conducted experiments of advanced treatment of rural sewerage with Biogeofilter (BGF) that was built in a rural sewerage plant. In a BGF filled with zeolite, we demonstrated that in 2004 the growth of forage rice plant was very bad because zeolite absorbed most of nutrition, but that in 2005 its growth and the removal rate of phosphorus were improved. Moreover it was suggested that NH_4-N was almost completely removed by the filled zeolite for two years when the secondary treated water of the average NH_4-N concentration 33mg/L was provided to a BGF at the time interval of one day and a half.We also constructed three series of BGF for the environmental education for elementary school children. We planted flowers, vegetables and resource plants such as sesbania and papyrus in these BGF. In biotope ponds we brought killifish and loaches from the surrounding paddy fields, and observed their growth. We observed that the bio-diversity in the ponds was maintained. After the plantation of plants, the observation of the growth and the final presentation by school children, we clarified that the environmental consciousness of the children was stimulated and that teachers gave a high evaluation to this experiment. These researches suggest that it is important, for effective advanced treatment of rural sewerage, to make up appropriate combination models of filter materials and plants considering their nutrition absorbing abilities so that we could reach the target of treated water quality.