| 摘要: |
| 绿地土壤换填介质性能对海绵城市雨水径流源头削减起着至关重要的作用。为解决西咸新区海绵城市绿地土壤换填介质（土∶沙∶椰糠=4∶4∶2，体积比）去污性能不佳和椰糠遇水漂浮的问题，通过设置不同质量浓度（0.00%、0.50%、0.75%、1.00%、1.50%）的聚丙烯酰胺（polyacrylamide，PAM）溶液与换填介质进行混合，测定其饱和导水率、饱和含水量、全氮（TN）、全磷（TP）、化学需氧量（COD）以及重金属铜（Cu）、锌（Zn）和镉（Cd）静态吸附效果。结果表明：与不添加PAM处理相比，用量为0.75%、1.00%、1.50%（质量分数）的PAM处理，介质的容重分别显著降低了9.1%、10.8%、12.2%；用量为1.00%、1.50%的PAM处理，介质的饱和含水量分别显著增加了24.3%、30.0%；用量为1.50%的PAM处理，介质的饱和导水率显著提高了52.6%；不同处理对TN和COD的吸附效果没有显著影响；与对照相比，用量为0.75%、1.00%、1.50%的PAM处理，滤液中磷的含量分别显著增加了20.1%、31.3%、51.1%；PAM的添加增加了介质对Cu、Zn和Cd的吸附。总之，用量为1.50%的PAM处理对于介质容重、饱和含水量、饱和导水率及对污染物（TN、COD、Cu、Zn、Cd）的静态吸附效果方面表现最优，因此推荐1.50%的PAM与土∶沙∶椰糠（4∶4∶2）配合可作为西咸新区绿地土壤换填介质。 |
| 关键词: 聚丙烯酰胺 椰糠 换填介质 物理性状 污染物去除率 |
| DOI：10.7515/JEE192016 |
| CSTR：32259.14.JEE192016 |
| 分类号: |
| 基金项目:陕西省重点研发计划项目（2017ZDXM-SF-083） |
| 英文基金项目:Key Research and Development Program of Shaanxi (2017ZDXM-SF-083) |
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| Effects of polyacrylamide and coir on the media infiltration, retention and purification in urban greenland soils |
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MA Xiao, WANG Chenguang, HAO Shan, GAN Xu, ZHANG Afeng, WANG Xudong
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1. Sponge City Technology Center, Fengxi New Town, Xixian New District, Xianyang 712000, China
2. College of Natural Resources and Environment, Northwest A&F University, Yangling 712100, China
3. Fengxi New City of Xixian New Area Administration of Shaanxi Province, Xianyang 712000, China
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| Abstract: |
| Background, aim, and scope Bioretention, a promising technology for urban stormwater pollution treatment. The mixture of soil, sand and coir was recommended to use as a bioretention media in the sponge city of the Fengxi New Town. The media amelioration was significantly enhanced soil infiltration, however, there were still problems on soil purification and the coir was floating with the stormwater. In order to improve the current situation, this study mixed PAM with the soil, sand and coir (the volume ratio is 4∶4∶2), to investigate the effects of different dosages of PAM on saturated water content, saturated water conductivity and pollutant removal rate. Materials and methods The emulsive PAM with different dosages (0.00%, 0.50%, 0.75%, 1.00%, 1.50%) (w/w) were mixed with the soil, sand and coir (the volume ratio is 4∶4∶2), which was incubated at laboratory lasted 20 days, the medium water content kept at 15% during the incubation study. And then saturated water conductivity, water content and chemical oxygen demand (COD), total nitrogen (TN), total phosphorus (TP), copper, zinc and cadmium contents in different leachates were measured to evaluate the pollution removal rate. Results The ratio of different amount of PAM and coconut chaff was important to improve the physical and chemical properties of the filter media. Compared with the control, the medium bulk density was decreased by 9.1%, 10.8% and 12.2% under PAM amendment at 0.75%, 1.00% and 1.50%, respectively. The saturated water content and saturated water conductivity were increased by 30.0% and 52.6% under PAM amendment at 1.50% treatment, respectively. However, there was no significant difference between other treatments and the control. Compared to the control, the content of COD and total nitrogen of the leachate was no significant under PAM amendment. However, the content of phosphorus of the leachate increased by 20.1%, 31.3% and 51.1% under PAM amendment at 0.75%, 1.00% and 1.50%, respectively. The addition of PAM increases the removal rate of Zn, Cu and Cd. Discussion PAM can effectively improve soil structure, reduce soil bulk density, increase the total soil porosity and capillary porosity, maintain the stability of soil particles and pore structure, thereby increasing soil infiltration rate and soil moisture content. PAM directly affects the adsorption of pollutants by the media through its molecular structure, and indirectly affects the adsorption of pollutants by the media through the effect on soil structure. Application of PAM can influence on soil physical and chemical properties, and the changes depended on the emulsive PAM rate. Conclusions The mixture of soil, sand, coir (4∶4∶2 (v∶v∶v)) and with PAM (1.50% (w/w)) amendment was recommended to use as a soil amelioration in the sponge city of the Fengxi New Town. Recommendations and perspectives We should be based on the actual situation of the soil, and comprehensively consider the effects of the infiltration, retention and purification, in order to select a suitable replacement media for the local. |
| Key words: polyacrylamide coir soil amelioration physical properties pollutant removal rate |
