海水人工湿地脱氮效果与系统内基质酶、微生物分析

Substrate Enzyme, Microbe Distribution and Denitrification Effects of the Constructed Sea Water Wetland

利用人工湿地系统探讨了海水养殖外排水中不同形态氮的去除效果,分析了系统内部微生物空间分布、基质酶活性对氮去除效率的影响,深入研究了系统内部各微生物间相互作用、基质酶活性与微生物空间分布关系。选择互花米草为人工湿地植物,种植密度为64株/m2;基质填料选择细纱、高炉矿渣和珊瑚石。在3种不同工况条件下,研究人工湿地系统中氮的去除效果、微生物数量和基质酶活性。结果显示,系统对TN、NH4-N平均去除率分别为(25.02±12.69)%、(82.91±17.51)%;系统中不同基质层次的微生物数量和脲酶、脱氢酶活性不同,基质中、上层好氧微生物数量和脲酶、脱氢酶活性显著大于下层,系统下行池中、上层硝化细菌、亚硝化细菌显著高于下层,中、上层反硝化细菌数量明显低于下层;细菌总数与TN(R2=0.50)和NH4-N(R2=0.61)去除率存在一定正相关性,基质脲酶与TN去除率存在显著正相关性(R2=0.86)。研究结果将有助于理解海水人工湿地处理系统中氮的迁移转化机制。

The substrate enzyme activity and the spatial distribution of microorganisms are important factors affecting the degradation of pollutants in water treatment system of the constructed wetland. The present study using a laboratory scale constructed wetland system in three different conditions to measure the removal effects of nitrogen, the relationship between the removal efficiency and the spatial distributions of microorganisms and the substrate enzyme activity. Spartina alterniflora was selected as the plant of the constructed wetland, and the density of reed was 64 per square meter. The substrates were filled with fine sand, coral rock and blast furnace slag. In three different conditions, the removal rate of different forms of nitrogen, the quantity and activity of microorganisms, the substrate activity were investigated. The results showed that the average removal rate of TN and NH4-N were （25.02±12.69）%and （82.91±17.51）% in the constructed wetland system during two-month stable operation, respectively. The quantities of microorganisms in different depths were obviously different, and the activities of substrate urease and dehydrogenase were different with depths. The quantities of aerobic microorganisms, the activities of urease and dehydrogenase in the upper and middle layer were significantly higher than those in the lower layer of the system. In the down flow tank of the system, the quantities of nitrifying and nitrite bacteria in the upper and middle layer were higher than those in the lower layer; however, the distribution of denitrifying bacteria was opposite. There were positive correlations between the removal rate of nitrogen and the quantity of bacteria and the enzyme activity （R2=0.50 and 0.61, respectively）. There was a significant positive correlation between the total nitrogen removal rate and the activity of urease （R2=0.86）. The results contribute to the migration mechanism of nitrogen in the constructed wetland system of treating marine aquaculture waste waters.