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

在大村湾沿岸地区的污水处理对策中，建造了利用土壤的各种排水沟，以准备公共污水。以控制内河水体富营养化为目的的“杂排水沟”的辅助产业，是廉价的家庭厨房排水，并期望立竿见影。这一辅助产业自1985年启动以来，初步目标已经完成，许多战壕已经报废。这一辅助行业自1985年开始推广，初期的目的已经完成，许多沟渠已经报废，但目前也用于公共污水系统以外的区域。对施工10年后经过的沟内土壤进行取样，调查磷酸吸收系数的降低情况，并对设施的使用寿命进行考核。调查结果表明，虽然磷酸吸收系数在开始时约为1000 - 1200，但目前已下降到500左右。因此，很明显，“战壕”的使用寿命为5年至7年，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.