A series of large pilot constructed wetland （CW） systems were constructed near the confluence of an urban stream to a larger fiver in Xi＇an, a northwestern megacity in China, for treating polluted stream water befo...A series of large pilot constructed wetland （CW） systems were constructed near the confluence of an urban stream to a larger fiver in Xi＇an, a northwestern megacity in China, for treating polluted stream water before it entered the receiving water body. Each CW system is a combination of surface- and subsurface-flow cells with local gravel, sand or slag as substrates and Phragmites australis and Typha orientalis as plants. During a one-year operation with an average surface loading of 0.053 m3/（m2.day）, the overall COD, BOD, NH3-N, total nitrogen （TN） and total phosphorus （TP） removals were 72.7% ~ 4.5%, 93.4% ＋ 2.1%, 54.0% ＋ 6.3%, 53.9% ~ 6.0% and 69.4% ：t： 4.6%, respectively, which brought about an effective improvement of the fiver water quality. Surface-flow cells showed better NH3-N removal than their TN removal while subsurface-flow cells showed better TN removal than their NH3-N removal. Using local slag as the substrate, the organic and phosphorus removal could be much improved. Seasonal variation was also found in the removal of all the pollutants and autumn seemed to be the best season for pollutant removal due to the moderate water temperature and well grown plants in the CWs.展开更多
The efficiencies of two types of constructed wetlands for the treatment of low-concentration polluted eutrophic land- scape river water were studied in the western section of the Qingyuan River at the Minhang campus o...The efficiencies of two types of constructed wetlands for the treatment of low-concentration polluted eutrophic land- scape river water were studied in the western section of the Qingyuan River at the Minhang campus of Shanghai Jiaotong University.The first wetland was a single-stage system using gravel as a filtration medium,and the second was a three- stage system filled with combinations of gravel,zeolite,and fly ash.Results from parallel operations of the wetlands showed that the three-stage constructed wetland could remove organics,nitrogen, and phosphorus successfully.At the same time,it could also decrease ammoniacal odour in the effluent.Compared to the single-stage constructed wetland,it had better nutrient removal efficiencies with a higher removal of 19.37%-65.27% for total phosphorus (TP) and 21.56%- 62.94% for total nitrogen (TN),respectively,during the operation period of 14 weeks.In terms of removal of chemical oxygen demand (COD), turbidity,and blue-green algae,these two wetland systems had equivalent performances.It was also found that in the western section of the test river,in which the two constructed wetlands were located, the water quality was much better than that in the eastern and middle sections without constructed wetland because COD,TN, and TP were all in a relatively lower level and the eutrophication could be prevented completely in the western section.展开更多
基金supported by the National Natural Science Foundation of China(No.50838005,51021140002)the Program for Innovative Research Team in Shaanxi(No.2013KCT-13)
文摘A series of large pilot constructed wetland （CW） systems were constructed near the confluence of an urban stream to a larger fiver in Xi＇an, a northwestern megacity in China, for treating polluted stream water before it entered the receiving water body. Each CW system is a combination of surface- and subsurface-flow cells with local gravel, sand or slag as substrates and Phragmites australis and Typha orientalis as plants. During a one-year operation with an average surface loading of 0.053 m3/（m2.day）, the overall COD, BOD, NH3-N, total nitrogen （TN） and total phosphorus （TP） removals were 72.7% ~ 4.5%, 93.4% ＋ 2.1%, 54.0% ＋ 6.3%, 53.9% ~ 6.0% and 69.4% ：t： 4.6%, respectively, which brought about an effective improvement of the fiver water quality. Surface-flow cells showed better NH3-N removal than their TN removal while subsurface-flow cells showed better TN removal than their NH3-N removal. Using local slag as the substrate, the organic and phosphorus removal could be much improved. Seasonal variation was also found in the removal of all the pollutants and autumn seemed to be the best season for pollutant removal due to the moderate water temperature and well grown plants in the CWs.
基金the National High Technology Research and Development Program of China (863 Program)(No.2002AA601013).
文摘The efficiencies of two types of constructed wetlands for the treatment of low-concentration polluted eutrophic land- scape river water were studied in the western section of the Qingyuan River at the Minhang campus of Shanghai Jiaotong University.The first wetland was a single-stage system using gravel as a filtration medium,and the second was a three- stage system filled with combinations of gravel,zeolite,and fly ash.Results from parallel operations of the wetlands showed that the three-stage constructed wetland could remove organics,nitrogen, and phosphorus successfully.At the same time,it could also decrease ammoniacal odour in the effluent.Compared to the single-stage constructed wetland,it had better nutrient removal efficiencies with a higher removal of 19.37%-65.27% for total phosphorus (TP) and 21.56%- 62.94% for total nitrogen (TN),respectively,during the operation period of 14 weeks.In terms of removal of chemical oxygen demand (COD), turbidity,and blue-green algae,these two wetland systems had equivalent performances.It was also found that in the western section of the test river,in which the two constructed wetlands were located, the water quality was much better than that in the eastern and middle sections without constructed wetland because COD,TN, and TP were all in a relatively lower level and the eutrophication could be prevented completely in the western section.
