| In China, many rivers are slightly polluted and the mechanism of slightly polluted water is quite complicated. Because the traditional techology cost too much and there are many problemes, there is not economical and effective techology to recover that water. Constructed wetland is effective, apparent ecological effect, and invest less in running time , it becomes an important techology to recover slightly polluted water.This paper is about removal in initiating phase and stable phase .substrate static adsorption and dynamic adsorption was investgate. the removal in different type wetland was anlaysised, root activity and the activity of enzyme was determined. The results are as follows:COD, TN and TP can be removed by constructed wetland. The average monthly removal rate of them is11.7%～25.2%,5.3%～38.2%,33.3%～61.6%, From the relative analysis between influent pollutant load and removal rate, we found that COD, TN, TP in influent are positive related with the removal rate, and the relationship of COD load and removal is significant, but not TN and TP. If the substrate is construction waste, the removal rates of pollutants in the initailing phase and stabilization phase are apparently different. From the relative analysis between oxygen consumption rate and removal rate of pollutants, we found that the DO is not the limited factor for wetland to remove pollutants of slightly polluted water. Cl- concentration affect the efficience of wetland. And everything will restore if the content of Cl- is normal again.It also can be found that it is better removal in construction waste substrate wetland. And it is singnaificant different between intialing phase and stable phase. From the static adsorption test and dynamic adsorption test under different temperatures, we found that the higher temperature, the better adsorption.but the incrment of N , P adsorption among three kinds of subtrate are different, they are waste brickrubble>pebble. While Freundlich equation is better to fit the P absorption quantity. It can be concluded from dynamic adsorption that the substrate will be equilibrium between absorption and stripping in lower concentration, while the higher concentration was injected, the equilibrium was broken till the new equilibrium was setup. HRT effected the N/P absorption by substrate.The Arundo donax is perennial plant, when its root system growed stably, the wetland of giant reed presented high removal rate to the pollutants, and the average removal rate remained relatively stably; the relativity between the influent load and effluent concentration in starting stage and stable stage showed that under certain influent load, the removal rate of COD and TN in starting stage is higher than stable stage. The root activity comparison discovered that warm season roots presented higher activity than the cold season roots, regarding the different plants, the canna root activity is the highest, in warm season the pollutant removal is comply the root activity, but not in cold season.The determination of enzyme in consructed wetland discovered that: enzyme in rhizosphere soil presented seasonal variation; dehydrogenase activity is highest in May and then decrease gradually. Catalase activity is low in July, August and December. Urease activity fluctruate monthly. T-test found that with different plants, there were significant differences on the dehydrogenase,while the catalase and the urease were not; the enzyme activity in wetland soil changed along the water inlet direction , namely that the more far away from the water inlet, the enzyme activity was lower. The relativity between the enzyme activity and the removal rate to the pollutants considered that there was a positive relationship between them. while the relativity impact significance of each wetland was different.
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