| Ammonia nitrogen is one of the main pollutants of surface water and groundwater,through nitration can form to nitrite and nitrate.The transformation of ammonia nitrogen into nitrate nitrogen can promote the absorption and assimilation of nitrogen by organisms,play a key role in promoting the transformation of nitrogen form and nitrogen cycle,and is of great significance to the ecological environment.In this paper,we mainly establish an ecosystem through the simulation of ficus-nitrifying bacteria and zebrafish,which reveals the effects of single factors such as anubias,exogenous nitrobacteria,external carbon source and temperature,composite factors such as anubias-exogenous nitrobacteria,anubias-zebrafish and anubias-exogenous nitrobacteria-zebrafish on nitrogen form transformation in water with three different initial concentrations of ammonia nitrogen.In addition,under the conditions that the water temperature is 20 oC and the plant planting density is 2.5g·L-1,the effect of the introduction of anubias and nitrobacteria on the transformation of ammonia nitrogen form in urban river sewage（actual water body）was investigated.In the study of the influence of a single factor,the planting density of 2.5 g·L-1was determined as the amount of plants used in the subsequent experiment.Anubias can effectively reduce the concentration of ammonia nitrogen in water and promote the conversion of ammonia nitrogen from nitrite nitrogen to nitrate nitrogen.The ammonia nitrogen in the water body with the initial ammonia nitrogen concentration of 4mg·L-1 was completely removed on the day 12,the water body with the initial ammonia nitrogen concentration of 8mg·L-1 was completely removed on the day 16,and the water body with the initial ammonia nitrogen concentration of 15mg·L-1 was completely removed on the day 20.The removal rate of ammonia nitrogen was accelerated with the increase of time.The total dissolved inorganic nitrogen of water also decreased under the action of anubias.Temperature also had a certain effect on nitrogen transformation in water.The ammonia removal and nitrogen transformation rates of water under 20 oC were significantly faster than those under 16 oC.Exogenous nitrobacteria can help remove ammonia nitrogen from water to some extent,but due to the lack of stable carbon source,the ammonia nitrogen removal ability of water has been at a low level,which is only slightly improved compared with the control group without exogenous nitrobacteria.Under the condition of additional carbon source,the ammonia nitrogen removal ability of water increased with the increase of C/N.Compared with the control treatment and nitrifying bacteria treatment without adding carbon source,the decrease of ammonia nitrogen and the rate of nitrogen transformation were significantly increased after adding carbon source.For many factors influence the transformation of nitrogen forms,the addition of exogenous nitrobacteria would have an impact on the original microbial system of roots.Anubias-exogenous nitrobacteria will lower nitrogen conversion rate in the ecological system,which is negatively related to the initial concentration of ammonia nitrogen in water and weakens over time.The addition of zebrafish will add new carbon and nitrogen sources to the water body,so as to improve the removal rate of ammonia nitrogen by anubias,but it will increase the total dissolved inorganic nitrogen in the water body.Exogenous nitrobacteria and zebrafish will interact with each other.The combined addition of exogenous nitrobacteria and zebrafish can improve the removal ability of ammonia nitrogen by anubias and alleviate the accumulation of nitrite nitrogen in water,but it will increase the nitrogen load of water,and the improvement of the removal ability of ammonia nitrogen of the system is not as good as adding zebrafish alone.The synergism of anubias-nitrobacteria was applied to the treatment of urban river sewage,and it was obvious that anubias and anubias-nitrobacteria also promoted the removal of ammonia nitrogen and the transformation of nitrogen. |
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