The Research On The Treatment Of High Concentration Sewage By Subsurface Flow Constructed Wetland

As a new sewage treatment technology,Constructed Wetland is constructed according to the principle of natural wetland.It takes the advantage of the cooperation among substrate,microorganism and plants to improve the quality of sewage.In this paper,the removal efficiency of organics,TP,TN and NH₄⁺-N in high concentration sewage by subsurface flow constructed wetland and the relations among substrate,microorganism and plants were researched.At first,based on the method of orthogonal test,four kinds of different experimemal devices were constructed which componented by different matrix(pumice and ceramsite),different plants(reed and iris)and different micro-organisms(NO.1 and NO.2).This experiment was taken in winter in north(the average temperature is 9.56℃),The results are as follows:(1) For the removal of organics,TN and NH₄⁺-N,the best efficiency appears in the NO.4 experimental system(ceramsite+reed+NO.1) with the condition of 6d HRT.In this condition,the highest influent concentration of organics,TN and NH₄⁺-N are 731.25mg/L,113.31mg/L and 96.36mg/L,and the highest effluent concentration of organics,TN and NH₄⁺-N are 183.22mg/L,54.21mg/L and 51.18mg/L,respectively. The highest removal rate of organics,TN and NH₄⁺-N can reach to 82.93%,55.95%and 52.21%,respectively.But for the removal of TP,the best efficiency appears in the NO.2 experimental system(ceramsite+iris+NO.2) with the condition of 6d HRT,the highest influent concentration and effluent concentration are 15.07 mg/L and 4.49mg/L,respectively, and the highest removal rate is 72.61%.(2) In winter,the pollutants removal by matrix is the most significant,microbes is the second,and the final is plant.(3) When comparing the pollutants removal rate,the two levels of matrix,pumice is better than ceramsite,but there are little difference between the two levels of plant(reed and camalus) and the two levels of micro-organisms(NO.1 and NO.2).(4) The removal rate of organics,TN,NH₄⁺-N and TP can rise 14.83%,12.27%,16.07%and 5.74%,respectively,when the microbial agents were added in the experimental system.(5) First-order kinetic model can be used to explain the removal disciplinarian of pollutions in constructed wetland.As a low-cost,highly efficient sewage treatment technology,constructed wetland has effective removal rate for organics TP,TN,and NH₄⁺-N when treating high concentrated sewage.