促沉装置净化稻田径流排水中面源污染物的效果研究

Efficacy of a Sedimentation-boosting and Purifying Device for Decontaminating Pollutants in Surface Runoff from Paddy Field

【目的】研究促沉净化装置对稻田径流排水中主要面源污染物的去除效果,探寻适合农田径流排水的原位处理技术。【方法】于2015年在上海市奉贤区青村镇种源研发基地内选取5块稻田,在每块田的排水口处修建一套容积约为1.9 m^(3)的促沉净化装置,内部用多面空心球和沸石按1∶2的体积比进行填充,在外围用沸石填充,分析每套装置进出水中的固体悬浮物、总氮和总磷的质量浓度。【结果】在整个稻季中,使用促沉净化装置对稻田径流排水中的固体悬浮物、总氮和总磷均具有较好的去除效果,其平均去除率分别达到61%、33%和34%。该装置对固体悬浮物或总磷的去除率与其质量浓度之间存在显著的对数正相关关系,即质量浓度越高,其去除率也越高;但对总氮的去除率与其质量浓度之间则呈一定程度的线性负相关关系。【结论】促沉净化装置对稻田径流排水中主要面源污染物均有较好的去除效果,使用促沉净化装置可在不影响流速的情况下,有效降低径流排水中污染物的质量浓度,改善周边水体环境,维护水体生态系统平衡稳定。

【Background】The catchment of Tai lake is one of the most important rice production basins in China and rice-wheat rotation is its dominant cultivation.However,excessive use of water and fertilizers has led to nutrient loss and eutrophication.Since precipitation in the catchment is high and most of it fall during the rice growth season,nutrients leaching with runoff into rivers is one of the main non-point source of pollutants in the catchment.【Objective】The objective of this paper is to present a sedimentation-boosting and purifying device and study its efficiency for in situ removing the pollutants in runoff from rice fields.【Method】The experiment was conducted in 2015 at five paddy fields in Qingcun town,Fengxian district of Shanghai.A set of sedimentation-promoting and purifying devices each with a volume of 1.9 m^(3) were installed at the outlet of the drainage system in each field.The device was filled with plastic polyhedron hollow balls and zeolite at a volumetric ratio of 1∶2 in its inside part,and its outside part was filled with zeolite.During the experiment,we measured the concentrations of suspended solids,total nitrogen and total phosphorous in both inflow and outflow of the device.【Result】The removal efficiencies of the suspended solids,total nitrogen and phosphorous by the device during the rice growth season were 61%,33%and 34%,respectively.The removal efficiency of suspended solids and total phosphorus by the device was positively correlated with their concentrations in the inflow in a logarithmic form,while the removal efficiency of total nitrogen was negatively correlated to its concentration in the inflow.【Conclusion】The sedimentation-promoting and purifying device can effectively remove main pollutants in the runoff from the paddy fields.It can thus improve the aquatic ecosystem without affecting the drainage from the paddy fields.