The research of the waste water treatment using the soil. The treatment performance of the facilities which passed through 10 years.

在大村湾海岸带公共污水准备过程中，作为污水处理对策，建设了利用土壤的杂排沟。辅助行业以“杂排水沟”为目的，hold住内河航道的富营养化，是廉价的家庭厨房排水，并期待其立竿见影的效果。这一辅助产业从1985年开始推广，最初的目的已经完成，许多沟渠已经报废。这一辅助产业从1985年开始推广，最初的目的已经完成，许多沟渠已经报废。但目前在公共污水系统以外的区域也有使用。对施工后10年的沟内土壤进行取样，考察其磷酸吸收系数的降低情况，并对设施的使用寿命进行检验。研究结果表明，初期磷酸吸收系数约为1000 ~ 1200，目前已降至500左右。由此可见，“沟”的使用寿命为5 ~ 7、8年。

Miscellaneous Drainage Trench which utilized the soil was constructed as waste water treatment countermeasure of the Omura Bay coastal zone in the preparation of the public sewerage. The assistant industry to "the miscellaneous drainage trench" for the purpose of holding the eutrophication of inland waterway, is cheap home kitchen drainage, and it expects the immediate effectivity. This assistant industry is promoted since 1985, and initial purpose has already been finished, and many trenches are already scrapped. This assistant industry is promoted since 1985, and initial purpose has already been finished, and many trenches are already scrapped.However, it is used in zone outside of the public sewerage at present too. We sampled the soil in the trench which passed through the construction post-10 year, and reduction situation of the phosphoric acid absorption coefficient was investigated, and the service life of facilities was examined. As a result of the investigation, though phosphoric acid absorption coefficient in the beginning was about 1000〜1200, it decreased at about 500 at present. Therefore, it became clear that the service life of "trench" was 5〜7, 8 year.