Pollutant Removal Performance And Optimization Of The Modularized Constructed Wetland Based On Wave Flow

Setting the guide plate in the constructed wetland system can increase the flow distance of the water flow effectivelly.A new constructed wetland sewage treatment device-modular constructed wetland was proposed,there is no relevant specification reference for the modular constructed wetland guide plates setting at present,this paper systemically evaluate the effects of the setting mode of guide plate on the flow pattern and scrubbing performance of the constructed wetland module by the trecer tests,the numerical simulation combined and laboratory research method.In addition,the physical,chemical,and biological effects of wetland wastewater purification can be affected by changes in flow conditions.Therefore,it is necessary to conduct a more in-depth study on the operating parameters of constructed wetland module system with guide plate（wave-flow modular constructed wetland）.Meanwhile,the contribution of three different wetland plants in the purification process of pollutants in constructed wetland system was explored,and the purification effect and influencing factors（ROL,temperature and p H）of pollutants were analyzed.What was more,its scrubbing performance of the wave-flow modular constructed wetland under long-term operation was systematically evaluated.The main research results were as follows:（1）The hydraulic performance of the constructed wetland module could be improved effectively by setting the guide plate in the system reasonably.the optimum hydraulic performance of the module to be able to reach by setting guide plates（from280 mm and 290 mm dependent on its height）with the lower part of the 1/3 front and the 2/3 upper part of the front of the wetland module,respectively,in the flow direction.（2）The optimized constructed wetland module has certain differences in the removal effect of each pollutant under different HRT.The pollutant purification effect is better with the increase of the HRT when the HRT is during certain range.When the hydraulic retention time continues to increase,the pollutant removal rate decreases.（3）Acorus gramineus Aiton is more conducive to the removal of nitrogen and organic matter than Pistia stratiotes and Eichhornia crassipes.The water-producing plants have strong anti-pollution ability in water,and the developed root system provides habitat for Phosphate accumulating organisms,which has a good absorption effect on phosphorus.p H and temperature and plant root oxygen diffusion capacity are important factors influencing the decontamination performance of wetland plants.What was more,the removal effect of organic matter and nitrogen is better when the p H of the system is 6.5～7.0,and the alkaline environment is favorable for the removal of TP.Compared with the Pistia stratiotes and Eichhornia crassipes,the roots of the Acorus gramineus Aiton are more powerful in ROL.（4）The results indicated that,the amount of HRT of wetland plants is thin,and it is difficult to meet the demand for DO in the process of organic pollutant degradation and ammonia nitrogen nitration.Therefore,that the water flow in the lower part of the module repeatedly enters the upper part of the module with setting mode of guide plate.it is necessary to increase the DO supply in the subsurface wetland.（5）The extension of the HRT within a certain range is conducive to the removal of pollutants.The results showed that the removal rates of COD,NH₃-N,TN and TP from the practical domestic sewage were 83.57%,74.49%,50.03%and 59.69%,respectively,after the stable operation of the wetland system.Which satisfied the first class A Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant（GB 18918-2016）.What was more,the unit wetland module is simple and convenient to install,has a small footprint,low operating cost,and has broad application prospects.