The Experimental Investigation On The Treatment Of Nitrogen And Phosphorus Of Domestic Sewage By Integrated Vertical-Flow Constructed Wetland

In this paper the principles of removal from wastewater in constructed wetlands, the major dynamical model, design method were discussed, and problems existed with constructed wetlands were also described. Base on the areal variation, we researched the benefit and discipline of nitrogen and phosphorous removal. First of all, through tests to determine integrated vertical-flow constructed wetland in the best operating conditions, and then orthogonal analysis was used on the integrated vertical-flow constructed wetland to find out nitrogen, phosphorus effect of the main factors. To carry out the major factors that affect the multi-level pilot study of N, P and purifying effect of the law. And the establishment of the nitrogen and phosphorus pollutants was maded, such as the first-order kinetics equation between HRT and N and P contamination .Analyses of the conclusions of the study were as follows:(1)The operation of integrated vertical-flow constructed wetland had a great effect on the sewage purification. Canna and cyperus integrated vertical-flow constructed wetland system, the hydraulic loading for 181.25mm/d of the five studies under the condition of purifying effect. The results showed that the cycle to run for 6 hours, shut-down 3 hours water , and water inflow 3 hours were the best purifying condition, wetlands beds CODcr, NH₃-N, TN, TP of the water quality reached the Grade A standards of "Urban Sewage Treatment Plant Emission Standards (GB 18918-2002) "; The removal rate of CODcr, NH₃-N, TN, TP were 93.2%, 73.5%, 70.54%, 92.5% by canna wetlands bed, and the removal rate of CODcr, NH₃-N, TN, TP were 88.6%, 58.1%, 65.84%, 91.6% by cyperus wetlands bed.(2) Orthogonal test results showed that: four factors that affect the role of ammonia nitrogen and total phosphorus were listed: process> hydraulic loading> pH value> CODcr, and the role on TN were listed: flow> hydraulic loading> CODcr> pH value.(3) The effects of integrated vertical-flow constructed wetland purification system had a close relationship with hydraulic loading, and the purifying effects of two sets of wetland bed were decreased with the increasing of hydraulic loading.When the hydraulic loading was at 241.5mm/d, two wetland bed of the water pollution indicators were lower than the Grade A standards of "urban sewage treatment plant emission standards (GB 18918-2002)"; The removal rate of canna wetlands bed on CODcr , NH₃-N, TN, TP were 90.0%, 69.6%, 61.67%, 90.9%, and the removal rate of cyperus wetlands bed under this conditions of the hydraulic loading CODcr, NH₃-N, TN, TP were 85.3%, 54.8% , 55.92%, 87.78%. Conclusions of the analysis of the test showed that the use of integrated vertical-flow constructed wetland on sewage processing can be achieved good results at JiangXi.(4) Pollution load test studies had shown that pollution load have a significantly effect on the integrated vertical-flow constructed wetland. The removal load of CODcr, NH₃-N, TN, TP of was increased with increasing the pollution load, and both show a certain degree of linear relationship. And this showed that the integrated vertical-flow constructed wetlands were still some potential to enhance the wetland system of four or more pollutants within the scope of the trial, and there could be used to deal with a higher concentration of sewage.(5)The process in the sewage system had an important effect on purification of the wetlands. The removal rate of CODcr,NH₃-N,TN,TP were increased with the increasing of process, but the relationship has a different case. CODcr removal show good linear relationship with process in the whole. And NH₃-N, TN, TP removal show good linear relationship with a high degree of changes in the wetlands in the first half of the, but in the process turning point appeared to 850mm. At 1100mm, two wetland bed of the water pollution index reached the Grade A standards of "Urban Sewage Treatment Plant Emission Standards (GB 18918-2002)".(6) Integrated vertical-flow constructed wetlands in line with the law of the dynamics of a relationship for sewage nitrogen and phosphorus removal, the dynamic model of Canna wetlands bed of CODcr, NH₃-N, TN, TP were ln(Ce/C0)= -0.0561t-1.0579,ln(Ce/C0) = -0.0415t-0.1785,ln(Ce/C0)=-0.0214t-0.5403,ln (Ce/C0) = -0.0423t-1.2517; the dynamic model of cyperus wetland grass beds for CODcr, NH₃-N, TN, TP were ln(Ce/C0)=-0.0424t-1.0724,ln(Ce/C0)=-0.0273t-0.1589,ln(Ce/C0)=-0.0212t-0.4422,ln(Ce/C0)=-0.0295t-1.1265, correlation coefficient R2 were higher than 0.9.