污水氮浓度和NH4^＋/NO3^-比对粉绿狐尾藻去氮能力和植物体氮组分的影响

Effects of Wastewater Nitrogen Concentrations and NH_4^+/NO_3^- on Nitrogen Removal Ability and the Nitrogen Component of Myriophyllum aquaticum(Vell.) Verdc

采用溶液培养法,设置3个氮浓度20、100、200 mg·L-1和3个NH_4^+/NO_3^-比1∶0、0.5∶0.5、0∶1,研究污水氮浓度和NH_4^+/NO_3^-比对粉绿狐尾藻去氮能力和植物体氮组分的影响.结果表明,粉绿狐尾藻的生物量在第1周增长最快,其中氮浓度20 mg·L-1、100 mg·L-1时,生物量以NH_4^+/NO_3^-=1∶0处理最大;氮浓度200 mg·L-1时,以NH_4^+/NO_3^-=0.5∶0.5处理最大.粉绿狐尾藻在第1周对总氮、铵态氮和硝态氮去除速率最高,且随氮浓度升高而增加;氮浓度20 mg·L-1时,铵态氮和硝态氮的去除率无显著差异,氮浓度100 mg·L-1、200 mg·L-1时硝态氮的去除率高于铵态氮.粉绿狐尾藻氮积累量及对水体和底泥氮去除的贡献率均随氮浓度升高而增加,其氮含量和积累量均以第1周增长最快,氮浓度20 mg·L-1时氮积累贡献率以NH_4^+/NO_3^-=0∶1最大,氮浓度100 mg·L-1、200 mg·L-1时以NH_4^+/NO_3^-=0.5∶0.5最大.粉绿狐尾藻体内蛋白质、氨基态氮和硝态氮的含量均随氮浓度的升高而增加,且蛋白质>氨基态氮>硝态氮;NH_4^+/NO_3^-为1∶0和0.5∶0.5时蛋白质含量较高,NH_4^+/NO_3^-=1∶0时氨基态氮含量最高,NH_4^+/NO_3^-=0∶1时硝态氮含量最高.由此说明,在试验范围内,粉绿狐尾藻的去氮能力随污水氮浓度升高而提高,可以用于高氮浓度污水修复;粉绿狐尾藻喜铵态氮,但在100 mg·L-1以上的高氮浓度下以硝铵等比时生长和去除氮能力最强;粉绿狐尾藻体内氮组分受硝铵比调节,蛋白氮比例最高,铵态氮和硝态氮则分别随污水NH+4和NO-3比升高而提高.

Solution culture experiments were conducted to investigate the effect of wastewater nitrogen levels and NH4^＋/NO3^- on nitrogen removal ability and the nitrogen component of Myriophyllum aquaticum. Experiments with three nitrogen levels and NH4^＋/NO3^- were set up as follows： 20,100,and 200 mg·L^-1 and NH4^＋/NO3^-1 ∶ 0,0. 5 ∶ 0. 5,and 0 ∶ 1. The results showed that the biomass of plants increased fastest during the first week. The plants treated with NH4^＋/NO3^-= 1∶ 0 with nitrogen levels of 20 and 100 mg·L^-1 and those treated with NH4^＋/NO3^-= 0. 5∶ 0. 5 with a nitrogen concentration of 200 mg·L^-1 exhibited higher biomass than the others. The removal rates of water total nitrogen,ammonium nitrogen,and nitrate nitrogen during the first week were the maximum for all treatments and increased with water nitrogen levels. There were no significant differences in the removal rate between ammonium nitrogen and nitrate nitrogen with a nitrogen level of 20 mg/L,while with nitrogen levels of 100 and 200 mg·L^-1,the nitrate removal rates were higher than those for ammonium nitrogen. The Myriophyllum aquaticum nitrogen accumulation and its contribution rate to nitrogen removal from water and sediment were all increased with water nitrogen levels and increased fastest during the first week. The contribution rate of nitrogen accumulated by plants with NH4^＋/NO3^-= 0 ∶ 1 was the highest with nitrogen levels of 20 mg·L^-1,while plants with NH4^＋/NO3^-= 0. 5 ∶ 0. 5 were the highest with nitrogen levels of 100 and 200 mg·L^-1. The protein,amino,and nitrate nitrogen contents in Myriophyllum aquaticum plants were all increased by increasing water nitrogen levels with a ranking of protein content amino nitrogen content nitrate nitrogen content. The protein concentrations in plants with NH4^＋/NO3^-= 1∶ 0 and NH4^＋/NO3^-= 0. 5∶ 0. 5 were higher regardless of water nitrogen levels,while the amino nitrogen concentration in plants with NH4^＋/NO3^-= 1∶ 0 and the nitrate nitrogen content in plants with NH4^＋/NO3^-= 0 ∶ 1 were higher than the others. It was concluded that the nitrogen removal ability of Myriophyllum aquaticum was improved by raising water nitrogen levels under the tested condition,which indicates that Myriophyllum aquaticum could purify high nitrogen wastewater. Myriophyllum aquaticum is an ammonium-nitrophile,but had the strongest capacity for growing and removing wastewater nitrogen exhibited with higher than 100 mg·L^-1 nitrogen levels only with equal NH4^＋ to NO3^-. The nitrogen component concentrations of protein,amino,and nitrate in Myriophyllum aquaticum plant were all affected by the ratio of NH4^＋/NO3^-.