Study On The Treatment Of Aquaculture Wastewater In Constructed Wetlands With Different Combinations Of Myriophyllum Aquaticum And Acorus Calamus L.

Nitrogen pollution in agricultural water bodies is becoming more and more serious,and the treatment of swine wastewater is the top priority of alleviating agricultural non-point source pollution.Constructed wetland is considered to be the main measure to solve agricultural pollution because of its low cost,environmental friendliness,and recyclability.The combination of constructed wetland plants is the main way to optimize nitrogen removal in wetlands.This study is based on the Myriophyllum aquaticum wetland,combined with a common water purification plant-Acorus calamus L.Through the test device to simulate the operation mode of the constructed wetland,four different types of wetland plant combinations-Myriophyllum aquaticum+Myriophyllum aquaticum（MM）,Myriophyllum aquaticum+Acorus calamus L.（MA）,Acorus calamus L.+Acorus calamus L.（AA）,Acorus calamus+Myriophyllum aquaticum（AM）,were exploredthe actual treatment effect of pig-raising wastewater at three different stages（different loads）.The main conclusions are as follows:（1）The four types of simulated constructed wetlands all showed good TN removal effects under different loads,and the average TN removal rates during the entire operation period reached:85.02%（MM）,88.93%（MA）,87.17%（AA）,91.16%（AM）.According to the linear fitting model,the TN load removal rate is significantly related to the influent TN load,and the combined wetland AM has the highest TN removal and TN load removal rate.（2）The four types of simulated constructed wetlands all have NO₃^--N accumulation in different nitrogen loading stages,especially in the first stage of winter operation.（3）Plant harvesting is an important way to remove the TN load of the collocation planting Myriophyllum aquaticum constructed wetland,but it is a secondary way to match the planting Acorus calamus L.constructed wetlands.The single Myriophyllum aquaticum constructed wetland can absorb 41.9%of TN load through plant absorption,while the single calamus constructed wetland is only 4.37%.In addition,different nutrient environments have a greater impact on the nitrogen content in the body of Myriophyllum aquaticum,but less on the Acorus calamus L.（4）Nitrogen mass balance analysis showed that the denitrification method of a single green Myriophyllum aquaticum wetland was mainly plant absorption and microbial denitrification,while a single Acorus calamus L.constructed wetland mainly relied on sediment adsorption and microbial denitrification.Among them,the first-level unit planted Acorus calamus L.and the second-level unit planted Myriophyllum aquaticum had the best denitrification effect,and the TN removal efficiency reach 91.16%.This study provides reference and reference for the optimization of nitrogen removal in the Myriophyllum aquaticum wetland with different wetland plants...