Screening Plant For Constructed Wetland And Study On Nitrogen And Phosphorus Removal Ability In Winter And Pilot Scale Research

The Constructed wetland (C W) is a newly developed ecological technology used for wastewater treatment。As the characteristics of CW resembles neither to those of natural wetlands, nor to those of general terraneous environments, enhancement of the species diversity in CW has become an important topic in recentyears.Introduction of different hydrophyte species into CW system used for municipal sewage treatment can obtain high treatment efficiency for removal of CODCr,N, P at lower cost and less energy comsumption。Adsorbent fillers microorganisms and plants are the essential components in the CW system。Studies on selection of proper wetland plants and their adaptation to waterlogged conditions become thus one of key research issues。At present the plant type of CW is quite unitary especially plant stops growing or dying in winter。Due to low bio-activity at low temperature, the treatment efficiency of CW is low in the winter season, selection and application of winter plant species in CW system are therefore of high values for improvement of its treatment efficiency and sustainability。This research take the common plants of the subtropics area as experi-ments the material and carries on the experiment in the Central South University of Forestry and Technology Zhuzhou school district artificial wetland sewage treatment system。Divides into the non-winter plant and the winter plant two major parts according to the plant seasonal variation。The results obtained from present study are summarized as follows:1,This study taking 17 kind of non-winter wetland plants as a material, In synthesis application original each kind of wetland plant screening and in evaluating indicator's foundation, increases the plant adverse circumstance enzyme and the matrix enzyme, Then, cluster analysis was carried by all indicators。The result indicated:17 kind of plant's root system quantities, length, vigor, leaf blade peroxide enzyme activity, biomass, nitrogen phosphorus average density, nitrogen phosphorus accumulation ability, nearby root systems matrix Urease activeness and the Phosphoric acid enzyme activity existence certain difference。17 kind of wetland plants was clustering 3 broad headings according to purification potential synthetic evaluation system. The 1st broad heading for strong:Canna indica,Phragmites australis, Cyperus alternifolius, Scirpus validus, Thalia dealbata,Lythrum salicaria, Variegated canna.It taking 10 kind of winner plants as a material, increases the plant Peroxidase concen—tration,Root activity as parameter, the result indicated the 1st broad heading for Trifolium repens, Loliuwn perenne, Narcissus tazetta var.chinensis Roem, Oenanthe javanicaf(Bl.) DC, Brassica campestris.2,the result of examination of removal of nitrogen and phosphorus by winner plant indicated:Optimal resident time of wastewater in constructed wetland system was found to be 5 to 10 days and the highest plant uptake rate was detected in the fist five days.The average remove rate of exam plant to TN,TP,NH4+-N,CODCr respectively is 55.18%,63.40%,58.74%,18.50%.For Oenanthe javanica(Bl.), it gave high removal rate for TN when the N concentration in the sewage was lower than 300 mg/L while at N concentration higher than this level, the normal growth of the plant is affected.In general the ability of the plant species to remove CODCr,P,TN and NH4+-N follows the order:Loliuwn-perenne>Oenanthe javanica(Bl.) DC>Brassica campestris..The average removal rate for these pollutants reached higher than 60%.3,Multiple constructed wetland systemtake the artificial wetland as the main body and auxiliary by biology cell,biochemical cell,free surface-flow wetland and subsurface flow wetland,not only complementary unit treatment effect each other but also enhanced treatment efficiency.The system is a relatively stable system with high treatment efficiency. The Multiple constructed wetland system can reducing energy consum-ption, narrowing wetlant area,achieve the function of synergistic combina-tion.Multiple constructed wetland system average removal rate higher than 60% in the winter. Biological regulating pool play important roles in absorption and transformation of NH4+-N and TP, Aerobic biochemical pool treatment efficiency best of NH4+-N and CODcr, most obvious in subsurface flow wetland to CODcr and Tp and best efficiency in surface flow wetland best to TN.