Research On Influence Of Plant Species Richness On Function Of Constructed Wetland In The Different Seasons

As the cities and towns are developing rapidly, the use of water discharging from industry and living is improving, a lot of wastewater is hand untreated, would discharge via nonpoint source to surrounding, raising the eutrophication of lakes and rivers and ecological damage.Constructed wetland is a cheap water treatment technology which is fit of developing town. But the large scale use in the north faces many problems, operation in the low temperature and stability are the main problems. The paper use the aboriginal plants in the northeast and match them, analyze the effect of technology on the function of constructed wetland and its root microbial communities; according to the different inflow concentration levels, study the ecological stability in order to offer theoretical basis for realizing the large scale use and technological innovation in the north towns.In the normal temperature, in the continuous flow constructed wetland, stability of COD removal decline in the mix way, stability of NH4+-N removal is better in the mix way, but its removal rate is highest in the Calamussingle(69.44%), highest removal rate of NO3--N, TN and TP appear in the I-A, SP3 and T-I. In the intermittent flow, curve of concentration of pollution over time is fitted: COD is four polynomial, NH4+-N、NO3--N、TN、TP are exponential function. Degration of COD wave and will reduce HRT in the mix way, degration rate of NH4+-N is higher in the mix way in the mid and low concentration inflow, there appear NO3--N accumulation in the single way, SP3 and I-A have higher degration rate of TN(9.50mg/d·L, 7.06mg/d·L), I-A has highest degration rate of TP(1.21mg/d·L) in the low concentration inflow.Analyze the Shannon(H)diversity index 、Simpson(D)diversity index、Pielou evenness index(J) in the microorganisms of root, degree of diversity is higher in the single way. Rate of G+/G- is greater than 1 in the mix way, rate of aerobic/anaerobic are 1.53 and 2.22, the resistance of microorganisms of root in the mix way is stronger, ecological environment is better. Result of PCA indicates, Typha angustifolia, calamus single and T-I are similar, Iris minutoaurea single, I-Aand SP3 are similar, fungi, G+ and aerobic bacteria are representative of PC1, anaerobic bacteria is representative of PC2.Light saturated photosynthetic rate of plant in the single way is higher than the mix way in the strong light, but in the low light level, in general photosynthetic rate of plant in the mix way is higher than single way. Plant diversity redu ce water loss because of transpiration, at same time enhance efficiency of water using, improve efficiency of transportion of nutrients, besides, SP3 improve the stomatal conductance. Plant diversity increases the plant’s biomass, get rid of calamus, plant diversity improve the N 、P content, and SP3 improve the N 、P pool obviously. In the mid and low concentration inflow, POD and NR in the plant in the mix way are higher, declare that plant in the mix way in the mid and low concentration inflow have better adaptive capacity.In the low temperature, all groups emerg e the NO3--N accumulation, COD removal in the Iris minutoaurea single is affected weakest(1.85%), get rid of calamus, NH4+-N removal is not affected, TN removal in the I-A is affected weakest(0.46%), TP removal in the SP3 is affected weakest(16.78%); refer to MDA content of plant, Typha angustifolia and calamus in the SP3 reach lowest(18.8、12.4nmol/g), plant has stronger capacity of cold resistance and better ecological stability in the mix way.