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不同补水方式下砂壤土渗滤系统对硝态氮去除效果
引用本文:潘维艳,黄权中,张子元,普薇如,黄冠华.不同补水方式下砂壤土渗滤系统对硝态氮去除效果[J].农业工程学报,2017,33(8):197-203.
作者姓名:潘维艳  黄权中  张子元  普薇如  黄冠华
作者单位:1. 中国农业大学中国农业水问题研究中心,北京 100083;中国-以色列国际农业研究培训中心,北京 100083;2. 中国-以色列国际农业研究培训中心,北京,100083
基金项目:国家自然科学基金项目(51079149, 51639009)
摘    要:在水资源短缺的北京地区利用再生水回补城市河湖,一方面对于水资源的可持续利用有着十分重要的作用,另一方面也可能带来地下水环境的潜在污染风险.该文采用100 cm砂壤土柱模拟(河湖岸底)土地渗滤系统,设置定水头淹水、交替淹水落干、定流速补水和侧向补水4种不同再生水回补方式,研究再生水中硝态氮(NO3-N)在土地渗滤系统中的去除效果和迁移转化规律.结果表明,当水力负荷在0.25~2.65 cm/d范围内时,渗滤系统对NO3-N的去除率随着水力负荷的增大而减小;侧向补水方式下渗滤系统对NO3-N的去除效果最优,平均去除率高达96.1%.在定水头淹水和侧向补水方式下,系统对NO3-N的去除主要发生在土柱的上部,而交替淹水落干和定流速补水条件下,土柱中下部对NO3-N也有一定的去除作用.渗滤系统对NO3-N的去除主要取决于系统内部微生物的分布情况,土层中的反硝化细菌数量越大,该土层对NO3-N的去除率就越高.当水温在15~32℃范围内变化时,定水头淹水和交替淹水落干补水方式下,系统对NO3-N的去除率与温度分别呈指数和幂函数关系.该研究表明土地渗滤系统可实现再生水的进一步净化处理,可为再生水安全回补河湖提供参考.

关 键 词:温度  反硝化  水力  再生水  砂壤土  渗滤系统  NO3-N  反硝化细菌
收稿时间:2016/12/4 0:00:00
修稿时间:2017/4/22 0:00:00

Removal effect of nitrate nitrogen for sandy loam filtration system under different water supply conditions
Pan Weiyan,Huang Quanzhong,Zhang Ziyuan,Pu Weiru and Huang Guanhua.Removal effect of nitrate nitrogen for sandy loam filtration system under different water supply conditions[J].Transactions of the Chinese Society of Agricultural Engineering,2017,33(8):197-203.
Authors:Pan Weiyan  Huang Quanzhong  Zhang Ziyuan  Pu Weiru and Huang Guanhua
Institution:1. Center for Agricultural Water Research, China Agricultural University, Beijing 100083, China; 2. Chinese-Israeli International Center for Research and Training in Agriculture, Beijing 100083, China;,1. Center for Agricultural Water Research, China Agricultural University, Beijing 100083, China; 2. Chinese-Israeli International Center for Research and Training in Agriculture, Beijing 100083, China;,2. Chinese-Israeli International Center for Research and Training in Agriculture, Beijing 100083, China;,2. Chinese-Israeli International Center for Research and Training in Agriculture, Beijing 100083, China; and 1. Center for Agricultural Water Research, China Agricultural University, Beijing 100083, China; 2. Chinese-Israeli International Center for Research and Training in Agriculture, Beijing 100083, China;
Abstract:Reclaimed water has been widely used to restore rivers and lakes in water scarce areas as well as in Beijing City, China. However, refilling the rivers and lakes with reclaimed water may result in groundwater pollution. Purification is necessary prior to utilization in order to minimize the pollution and human-health risk. To study the long-term NO3-N removal efficiency during land filtration system under different water supply conditions, a long-term filtration system was built using soil columns supplied with reclaimed water from reclaimed wastewater treatment plant. Four sets of soil columns (100 cm in length, 20 cm in diameter) repacked with sandy loam soil were utilized to simulate the land filtration system. Four water supply conditions were considered including continuous wetting, alternating wetting/drying, constant flow rate and lateral injection. The results showed that NO3-N removal efficiency decreased with the increase of hydraulic loading rate when the hydraulic loading rate varied from 0.25 to 2.65 cm/d. Different NO3-N removal efficiencies were mainly attributed to the different hydraulic retention time under different water supply conditions. For the constant flow rate and lateral injection condition, longer hydraulic retention timewasconducive to efficient denitrification. Removal efficiency of NO3-N reached higher than 90% in the constant flow rate and lateral injection column. The highest removal efficiency of NO3-N was obtained in the column recharged with lateral injection, with an average removal efficiency of 96.1%. NO3-N concentrations in the effluents in the alternating wetting/drying, constant flow rate and lateral injection columns were all lower than the drinkable water standard (<10 mg/L). The transport and removal of NO3-N varied with soil depth. The variation trend of NO3-N removal along soil depth was different under different water supply conditions. For the continuous wetting and lateral injection condition, NO3-N concentration decreased rapidly in the top 20 cm depth. Top 20 cm layer of the sandy loam columns (0-20 cm for the continuous wetting condition, 40-60 cm for the lateral injection condition) was the main zone for NO3-N removal. For the alternating wetting/drying and constant flow rate condition, NO3-N concentration decreased gradually along the soil depth. For the alternating wetting/drying condition, NO3-N removal efficiency increased from 23.2% in 20 cm to 76.2% in 100 cm. For the constant flow rate condition, NO3-N removal efficiency increased from 20.8% in 20 cm to 94.1% in 100 cm. The results indicated that the NO3-N removal efficiency in different soil depths was correlated to the number of denitrifying bacteria in 4 soil columns. The results also showed that the NO3-N removal efficiency presented an exponential relationship with the temperature ranging from 15 to 32℃ under the continuous wetting condition. For the alternating wetting/drying condition, NO3-N removal efficiency showed a power function relationship with the temperature, while temperature had no significant influences on NO3-N removal under low hydraulic loading rate condition, i.e., constant flow rate and lateral injection condition. The results confirmed that the NO3-N removal performance under constant flow rate and lateral injection condition could both be relatively stable during the land filtration system's long-term running. The land filtration system could be used for further purification for reclaimed water. The result can provide important information for the reuse of reclaimed water in refilling rivers and lakes.
Keywords:temperature  denitrification  hydraulics  reclaimed water  sandy loam  filtration system  nitrate nitrogen  denitrifying bacteria
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