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

在准备公共污水时，建造了利用土壤的杂排水沟渠，作为大村湾海岸带的废水处理对策。辅助业以“杂水沟”为目的，遏制内河航道富营养化，是廉价的居家厨房排水，它期待立竿见影的效果。这个辅助行业从1985年开始推广，最初的目的已经完成，很多战壕已经报废。这项辅助工业自1985年开始推广，目前已完成初步用途，很多沟渠已被修整，但目前也用在公共污水收集系统以外的地方。对施工10年后通过的地沟内土壤进行取样，调查其磷酸吸收系数降低的情况，并对设施的使用寿命进行检验。研究结果表明，虽然磷酸的吸收系数最初在1000~1200左右，但目前已下降到500左右。由此可见，“地沟”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.