不同类型生态浮床对富营养河水脱氮效果及微生物菌群的影响

摘要

通过设施大棚内容积为1.5 m3的人工模拟池试验,研究了框式与传统旱伞草浮床对富营养河水氮素转化及微生物菌群的影响.传统浮床是以聚乙烯泡沫板为载体,栽植陆生植物来削减水体氮磷和有机物质等,从而达到净化水质的效果.框式浮床是以塑料镂空支架为载体,除种植陆生植物外还添加填料等组件的新型浮床.结果表明:①2种浮床对水体中TN,NH4+-N和NO3 -N均有显著的去除效果,其中框式浮床和传统浮床的NH4+ -N去除率分别高达91％和86％,TN去除率也分别达到74％和64％,NO3-N去除率分别为49％和31％.②2种浮床系统有效地提高了水体中微生物和氮循环细菌总数和种群数量,尤其是框式浮床不同时期均比空白对照高出2～3个数量级.③氮循环细菌的数量跟水体氮素去除有显著相关性.其中水体ρ( NH4+ -N)和氨化菌数量呈显著正相关,ρ(NH4+ -N)和硝化菌数量呈极显著负相关,ρ(NO3-N),ρ(TN)和反硝化菌数量之间呈极显著负相关.④框式浮床的独特结构使之比传统浮床的去氮能力更强.其中,填料系统吸附贡献率为8％,植物吸收的去氮贡献为16.5％,微生物系统脱氮则为75.5％；而传统浮床植物系统吸收贡献率为31.8％,微生物系统脱氮贡献率为68.2％.说明浮床系统中植物吸收只是系统去氮的一种途径,微生物脱氮在2种浮床脱氮途径中占主导作用.%The effects of two types of Cyperus alternifolius floating-beds - frame-bent compound ecological floating-bed ( FCEFB) and traditional floating-bed ( TFB)- on the removal of nitrogen and the community of nitrogen cycling-related bacteria in a eutrophic river were investigated in a greenhouse in an artificial pond with a volume of 1. 5 m3. TFB is a traditional technology which uses a polyethylene foam board as a seedling bed to carry terraneous plants to reduce nitrogen, phosphorous and organic matter in contaminated water so as to purify water quality. FCEFB is a newly-developed floating-bed which uses a plastic hollow frame as a seedling bed, on which filters can be added in addition to planting terraneous plants. The results showed that; first, the removal efficiency of the FCEFB and TFB were significant in NH4 + -N by 91% and 86% , TN by 74% and 64% and NO3- -N by 49% and 31% , respectively. Second, the two floating-bed systems effectively increased the microorganisms, in terms of both total numberand population quantity of the nitrogen cycling-related bacteria in the water. The nitrogen cycling-related bacteria in the FCEFB were hundreds to thousands of times higher than those in the control at different sampling periods. Third, the number of nitrogen cycling-related bacteria had significant, linear correlation to the nitrogen removal from the polluted water. Relative coefficients of p(NH4+-N) showed extreme, significant, positive correlation with the number of ammonifiers, and extreme, significant, negative correlation with the number of nitrobacteria. On the other hand, p( NO3--N) and ρ(TN) showed extreme, significant, negative correlation with the number of denitrifying bacteria. Fourth, the FCEFB was more efficient at nitrogen removal than the TFB due to its special structure. The contribution rate of nitrogen removal in the FCEFB was 18% by filter system absorption, 16. 5% by plant uptake and 75. 5% by the microbial system. In the TFB, the contribution rate of nitrogen removal was only 31. 8% by plant uptake and 68. 2% by the microbial system. It was concluded that plant uptake is only one method of nitrogen removal in floating-bed systems, and that biodenitrification via the microbial community may play a dominant role in the remediation of contaminated water in the two floating-bed systems.