A STUDY ON THE METHOD OF REMOVAL OF NITROGEN AND PHOSPHORUS FROM AGRICULTURAL DRAINAGE WATER

农业排水中氮、磷去除方法的研究

• 批准号: 02660233
• 负责人: MISAWA Shinichi
• 金额: $ 1.15万
• 依托单位: NIIGATA UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for General Scientific Research (C)
• 财政年份: 1990
• 资助国家: 日本
• 起止时间: 1990 至 1992
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02660233/
• 关键词: Water quality; Removal rate; Total nitrogen; Total phosphorus; sedimentation; 水質浄化; 農地河川; 窒素; 燐; 除去; 懸濁物; 燐酸鉄; 代掻; 沈殿; 懸濁態; 代掻き; リン酸鉄

It was found that almost all nitrogen in the drainage water from agricultural land are soluble forms except during the paddling and transplanting season, and phosphorus is always in the insoluble form. Phosphorus combines with iron(Fe) except during the paddling and transplanting season, in that season phosphorus combines with soil particles.In paddy fields on alluvial planes like the Niigata planes, by deoxidization, iron in the paddy soils becomes soluble, so phosphorus combined with the iron also becomes soluble. Through under-drains, water containing soluble phosphorus flows out into drainage channels.In the channels, by oxidization phosphorus changes to the insoluble form again and sinks to the channel bed when drainage discharge is small, during floods the sediments rises up and flow down the channels.If characteristics of sedimentation of phosphorus compounds could be utilized, it would become possible to remove phosphorus from the agricultural drainage water. It was found that the sediments on the channel beds, contains 10 times of phosphorus in paddy soil. Phosphorus volumes contained in sediments from the drainage channel located in front of the Shirone drainage pump station, reached nearly 10% of total effluent phosphorus.So there is a possibility of removing a lot of phosphorus from agricultural drainage water by artificial settling basins. It is almost impossible to remove nitrogen by sedimentation.

研究发现，农田排水中除划苗期和移栽期外，几乎全部氮为可溶态，而磷则始终为不溶态。磷与铁（Fe）结合，除了在划水和移栽季节外，在该季节磷与土壤颗粒结合。在新泻平面等冲积平面上的稻田中，通过脱氧，稻土中的铁变得可溶，因此磷与铁也变得可溶。含有可溶性磷的水通过暗渠流出，进入排水沟。在沟渠中，磷被氧化再次变成不溶性形式，当排水流量小时沉到沟床上，洪水时沉积物上升并沿沟渠向下流动。如果能够利用磷化合物的沉降特性，去除农业排水中的磷就成为可能。研究发现，河床沉积物中的磷含量是水稻土的10倍。 Shirone排水泵站前排水沟沉积物中的磷含量达到了出水磷总量的近10%。因此，通过人工沉淀池去除农业排水中的大量磷是有可能的。通过沉淀去除氮几乎是不可能的。