Study On Treatment Of Effluent In Municipal Secondary Sewage Plant With Constructed Wetland

China's current urban sewage treatment plant effluent quality is still a mostly poor V, the water is still not able to directly reuse, so needs further to purify. Because the traditional sewage reuse technologies are facilities complex, high running costs, for the majority of the sewage treatment plant is unbearable. Constructed wetland technology is a treatment technology, it is a good purifying effect, small investment, low running cost. Therefore this article in view of the sewage plant effluent might the biochemistry low, the water leakage still belong poor V, to carry on wetland purification of sewage water research.This article uses the model experiment method. First establishment constructed wetland model installment in outdoors, structure two stage constructed wetland systems. Next, carries on experiment in the constructed wetland purification sewage plant effluent, study removal effect of pollutants in different seasons, to the constructed wetland unloading phase, seasonal variation, pollutant change, the influence wetland purification effect factor and so on has conducted the monitor analysis research. Finally, according to small test results, the preliminary design suits the sewage treatment plant water leakage constructed wetland processing demonstration project, may take the reference for the experimental research. The results were as follow:(1) In the matrix and micro-organisms working together, constructed wetland system for wastewater NH3-N, TN, TP, the average removal rate is 68.2%,18.8%,29.8%; in most of the pH value is between 6.5 to 7.5, the environment to meet the growth of micro-organisms; dissolved oxygen in the between 0.45 to 3.74mg/L, the higher removal rate of NH3-N, dissolved oxygen in the within 0.45mg/L, the TN removal rate of the highest, TP removal efficiency with little change in dissolved oxygen, the removal are at a lower level.(2) In the matrix, micro-organisms and plants working together, Constructed wetland system for sewage BOD5, COD, NH3-N, TN, TP and E. coli, the average removal rate is 100%, 34.8%,59.3%,72.4%,70.8%and 94%; pH value between 6.5 to 8.5, the system has better removal of pollutants to meet the growth of micro-environment; The treatment effect from the vertical stratification of view, ammonia and phosphorus levels tend to result in uniform, there has been no obvious stratification.(3) Waste water Treatment Plant effluent due to lack of carbon source influence the effect of nitrogen removal efficiency, therefore add a carbon source can improve the nitrogen removal efficiency in winter. In the hydraulic loading is 0.43m/d, C/N= 10, TN removal rate reached 57%, and then add the carbon source while the removal rate stabilized. Under the conditions of abundant carbon (C/N> 10), hydraulic loading on nitrogen removal efficiency have a greater impact, hydraulic loading is about 0.43m/d is more suitable.(4) Aerobic and anaerobic conditions in bio-pond to be influential to the TN elimination rate. When the constructed wetlands on the TN removal rate are low in the autumn and winter, the average removal rate of about 25%, when changed to anaerobic pond, TN removal efficiency can reach 45%, increased by 20 percentage points. However, TP removal efficiency is no significant change.(5) Combination of two constructed wetlands have better purification effect of pollutants, after two-level treatment, can improve the removal rate of 20%-30%.