| Constructed wetland is a kind of ecological treatment processes, which have the characteristics of good treatment effect, low investment and short construction time, constructed wetland is suitable for the water treatment. To solve the problem of water pollution in Beijing's townlets, the paper author experimentized the experiments of water treatment by combinatorial constructed wetland. The content of experiments consisted of the treatment effect by different types of combinatorial constructed wetland, and the actions of wetland plants in sewage treatment. The research was composed of two parts:indoor experiment and outdoor experiment; the indoor experiment was carried out by the vertical flow-surface flow constructed wetland and the outdoor experiment was carried out by horizontal flow-surface flow constructed wetland. The results showed that:(1)The vertical flow-surface flow constructed wetland can purify the sewage effectively, the removal rates of COD, TN, TP and NH3-N were 80%,70%,55% and 60%. The pollutants were wiped off by vertical flow part, and the horizontal flow part can make further improvement on COD, TN and NH3-N removal, but not included TP.(2) The experiment proved that activated sludge can promote the biomembrane's growth, shorten the starting time and improve the rate of removals.(3) The plants in constructed wetland can improve the rate of removals in two ways:absorbing and providing inserted condition for microorganism. The effects of plants absorbing had some connection with the technics of constructed wetland, horizontal flow was better than vertical flow in the process of plants absorbing.(4)The horizontal flow-surface flow constructed wetland can purify the sewage effectively, the removal rates of COD, TN, TP and NH3-N were 65%,70%,60% and 75%. The pollutants were wiped off by horizontal flow part, and the surface flow part can make further improvement on TN and NH3-N removal, but not included COD and TP.(5)The pollutants removal effects of outdoor constructed wetland in unloading phase was unsatisfactory, the pollutant levels of effluent were higher than entry. After the unloading phase, the biomembrane system was formation and the pollutants on the surface of filler were discharged from the constructed wetland, so the effect of pollutants removal was better than before.(6)Because of the ample illumination, the growth vigor of wetland plants in outdoor experiment were better than indoor experiment, and the contribution rate of outdoor experiment plants was higher. Plants' growth vigor in surface flow constructed wetland were better than those in subsurface flow constructed wetland, the same as biomass and the plants'content of nitrogen and phosphor. The plants, which in surface flow constructed wetland, removal contribution rate of TN and TP were higher than those in subsurface flow constructed wetland.(7)Because the surface flow constructed wetland in outdoor have the good condition of ventilation, the removal rate of NH3-N was higher than COD, TN and TP,... |
