Planned Reuse of Domestic Wastewater in Rural Area

首先，对研究进行了综述。其次，为了明确农村污水处理废水回用农业的实际情况，对具有代表性的18条农村污水和4条公共污水进行了调查。主要发现：1)主要目的是防止水资源短缺。未考虑处理后废水的肥效和农田的净水功能。2)处理后的废水主要用于水田。3)在许多情况下，每年整个灌溉季节都进行重复利用。4)处理后的农田废水排放系统多种多样。5)处理后废水规划条件的确定未考虑回用。6)采用了各种各样的处理系统。并对这些条件下的重用问题进行了定义。第三，对爱媛县“O区”进行了实地调查，实地开展了处理后的废水回用水田的实践。在该地区，处理后的废水在灌溉池或河水中稀释。主要研究结果如下：1)在一般施肥和农药利用条件下，重复利用使水稻植株获得普通收获。2)处理后的废水中大肠菌群和异养菌的数量小于该地区天然水（如河水）。3)水田对NOx-N具有有效的净化功能。4)处理后的废水排入池中，导致过流量水量增加。这种情况导致管理池塘水门的劳动力减少。5)夏季入池处理后的废水往往混合不完全，停留在1 ~ 2m深度。还澄清了保留的原因。

Firstly, the review of the research was conducted. Secondly, in order to define the actual status of the reuse of the treated wastewater from rural sewerage for agriculture, representative 18 rural sewerage and 4 public sewerage were investigated. Main findings are : 1) The main purpose was the prevention of the water shortage. Fertilizer effect of the treated wastewater and the water purification function of the farmland were not considered. 2) The treated wastewater was mainly utilized for paddy fields. 3) In many cases, the reuse were practiced throughout the irrigation season every year. 4) The sending systems of the treated wastewater for the farmland were very diverse. 5) The planning conditions of treated wastewater were determined without the consideration for the reuse. 6) A wide variety of treatment systems was employed. The problems for these conditions of the reuse were also defined. Thirdly, investigations of the "O area" in Ehime prefecture were conducted, where the treated wastewater reuse for paddy fields was actually practiced. In the area, the treated wastewater was diluted in the irrigation pond or by river water. Main findings are : 1) The reuse resulted in the ordinary harvest of rice plants under the general conditions of the fertilization and the utilization of agricultural chemicals. 2) The number of coliform groups and heterotrophes in treated wastewater were smaller than the natural water in this area : e.g. river water. 3) The purification function of paddy fields were effective for NOx-N.4) The sending of the treated wastewater to the pond resulted in the increase of the volume of over flow water. This condition led to the reduction of labor for management of the water gate of the pond. 5) The treated wastewater sent to the pond were tended to be not completely mixed and to be remained in the depth of 1-2m in the summer season. The reason of the retention was also clarified.