Study On The Effect Of Micro Aeration Compound Wetland Wastewater Treatment

Constructed wethand system is a new type of ecological waste water treatmend technology.It is a peocess with stable efficiency stronger ability for resisting shock load,low investment,convenient management,good landscape ecological effect and so on.It has superior technological performance and broad application prospect.On sewage treatment in small town.But tradionnal constructed wetland relies on plant roOPs to transmit oxygen effect which cause the wetland is serious lack of the ability of provide oxygen.Then those cause the microorganisms are inefficient which make the construceed wetland’s covering area is rather large in the processing of wetland water treatment.After the water in long run will be easy hander,clog and OPher problems.All of those situations produce severe effects on the application in sewage treatment of constructed wetland.Above the exiting defects the traditional constructed wetland,in this paper,the aeration system will be instructed to improve the ability of provide oxygen of wetland in the traditional constructed wetland.And the influencing factors on purification efficiency of aeration intensity,aeration patterns,temperature and reflux ratio was studied in pilOP plant.The opimal operation condition of wetland pilOP system was found by analysis of data,and it is applied in demonstration project.Main condusions can be summarized as follows.（1）The gas-water ratio of 3:1 has the best treatment effect was studied by the effect of different aeration intensity（0.5:1,1:1,2:1,3:1,4:1）on vertical flow constructed wetland treatment efficiency under the HRT 4d and the condition of continuous aeration.Compered it with no aeration,the removal rate of COD_cr,TN,NH₄⁺-N and TP was enhanced 16.27%,25.75%,55.48% and 21.59% in group A（Cyperus alternifolius L.）and 14.68%,17.83%,45.92% and 21.5% in group B（Iris wilsonii C.H.Wrighrt）.In the gas-water ratio of 3:1,the COD_cr and NH₄⁺-N effluent’s concentration achieves（GB18918-2002）level I of A standard,TN effluent’s concentration is level I of B standard and TP can reach（GB18918-2002）level secondary discharged standard,but on no aeration condition,in addition to COD_cr,the remaining water quality indicators can nOP meet the level of B standard.（2）Compared with different aeration patterns（continuous and intermittent）on the treatment efficiency of vertical flow constructed wetland found that continuous aeration has better treatment efficiency of TN and NH₄⁺-N,but no obvious change of COD_cr and TP.The removal rate of TN and NH₄⁺-N increased by 3.0%⁷.9% and 15.7%¹8.8% respectively,compared with the intermittent aeration condition.On the continuous aeration condition,the COD_cr and NH₄⁺-N can achieve（GB18918-2002）level I of A standard,TN concentration is level I of B standard,and TP reaches（GB18918-2002）level secondary discharged standard,but on the intermittent aeration condition,OPher than the remaining water quality indicators,only the COD_cr can achieve（GB18918-2002）level I of B standard.（3）The result showed that the best treatment efficiency was the reflux ratio of 1:1,through research on the wetland on wastewater treatment with different reflux ration（0.5:1,1:1,1.5:1,2:1）.At this condition,the removal rate of COD_cr,TN,NH₄⁺-N and TP respectively increased 4.42%,8.34%,1.55% and 4.41% in group A（Cyperus alternifolius L.）,the removal rate in group B（Iris wilsonii C.H.Wrighrt）enhanced by 4.41%,8.32%,0.94% and 1.4%.And the effluent’s concentration of COD_cr,NH₄⁺-N and TN achieves（GB18918-2002）level I of A standard,TP reaches（GB18918-2002）secondary standard,but with no reflux,COD_cr and NH₄⁺-N can reach level I of A standard,TN is to（GB18918-2002）level I of B standard,and TP is secondary standard.（4）At the reflux ratio of 1:1condition,the wetland of purification effect was effected by temperature.Compare low temperature with high,in group A and group B,the removal rate of COD_crdecreased by 12.18% and 8.48%,the TP reduced by 7.03% and 6.66%,and NH₄⁺-N decreased by 5.77% and 5.76%,respectively.In high temperature,the effluent’s concentration of COD_cr,TN and NH₄⁺-N reach（GB18918-2002）level I of A standard,TP gets level I of B standard,but in low temperature,only the COD_cr and NH₄⁺-N reach level I of A standard,the effluent’s concentration of TN achieves level I of B standard,and TP just reach secondary standard.All of those show that the removal rate of COD_cr,NH₄⁺-N,TN and TP of wetland will decrease with the decrease of temperature.（5）On the aeration condition,exisat the NO₃^-N accumulation phenomena,the removal rate of NO₃^-N will increase with the increase of gas-water.When the ratio of gas-water is 3:1,the effluent’s concentration of NO₃^-N respectively achieve 8.57mg/L and 9.21mg/L in group A（Cyperus alternifolius L.）and group B（Iris wilsonii C.H.Wrighrt）.On the optimal reflux ratio of 1:1condition,the effluent’s concentration of NO₃^-N reduced 3.19mg/L and 3.48mg/L,decreased 37.2% and 37.8%,respectively.to the no reflux.These show that the reflux is important to reduce the effluent’s concentration of NO₃-N.（6）The demonstration project of combined constructed wetland of microaeration was constructed and carry out the operation effect monitoring of one year.Through analyze the monitoring result,the new wastewater treatment process has better purification effect on sewage.It to the removal rate of COD_cr,NH₄⁺-N,TN and TP is 85.4± 9.8%,75.8%± 17.5%,65.3%± 12.6% and 64.8% ± 20.5%,respectively,and the treatment efficiency is obviously better in high temperature than it in low.In high temperature,the COD_cr and TN can reach（GB18918-2002）level I of A standard,NH₄⁺-N and TP can achieve level I of B standard,but only the COD_cr can reach level I of A standard in low temperature,OPhers like NH₄⁺-N and TN achieve（GB18918-2002）level I of B standard,and the TP just reach（GB18918-2002）secondary standard.