| With the rapid development of industrialization and economy,the natural environment of our country is accelerated and destroyed.The eutrophication of lakes is worsening.The frequency of cyanobacteria eutrophication triggered by lake eutrophication is also accelerating.The outbreak of algal bloom is a specific manifestation of eutrophication in water body,the fundamental reason is that the content of nitrogen and phosphorus in the water body is too much.At present,artificial salvage is the most effective treatment method of cyanobacteria bloom,but the salvage process consumed a lot of manpower and resources.Therefore,in this study,through the determination of nitrification and denitrification potential of algae bacteria and the determination of dissolved organic carbon in algae,the influencing factors in the process of denitrification were explored,and the feasibility of using salvaged cyanobacteria to treat high nitrogen wastewater was investigated.The experimental results are as follows:1.The effect of cyanobacteria concentration and ammonia nitrogen content on nitrification potential of the alga system showed that the higher the concentration of cyanobacteria,the faster the nitrification rate.In addition,the nitrification rate and nitrification activity of the treatment group with high ammonia concentration were significantly higher than those of the low ammonia concentration treatment group(P<0.01),indicating that the algal bacteria system can indeed carry out nitrification and denitrification reaction,and it can be applied to the treatment of high ammonia nitrogen wastewater.2.The effect of cyanobacteria concentration and nitrate nitrogen content on denitrification potential of algal bacteria system showed that the higher denitrification rate of cyanobacteria and nitrate nitrogen was,the higher nitrate nitrogen concentration would inhibit denitrification to a certain extent.The results of quantitative PCR showed that nirS and nirK genes existed in the total DNA from the cyanobacterial aggregates,indicating that there were lots of denitrifying bacteria in the cyanobacteria epiphyte.According to the rate of denitrification in this study,cyanobacteria and its epiphyte can remove 518.8 tons of nitrogen in Taihu by denitrification.3.The changes of dissolved organic carbon during the process of nitrification and denitrification of algae bacteria indicated that algal blooms could produce dissolved organic matter such as tyrosine,tryptophan and humic acid in the process of outbreak and decay The three fluorescence components were significantly correlated(P<0.01),indicating that these soluble organic matter may be derived in whole or in part from cyanobacteria,indicating that a large amount of organic carbon can be produced during the outbreak or decline of algal blooms.The results of physicochemical properties and spectroscopy showed that these dissolved organic carbons could be utilized by denitrifying bacteria in the algal bacterial system.Thermodynamic calculations show that the organic carbon provided by cyanobacteria at 1.5 ?g L-1 can be completely denitrified by 1 mg L-1 nitrate nitrogen,so there is no need to add carbon source in practical treatment.4.System of algae and bacteria with high nitrate wastewater field experiment showed that the photosynthesis and respiration system of algae and bacteria that nitrification and denitrification occur alternately,the night system of algae and bacteria for nitrate removal through denitrification,heterogeneous reduction of nitrate to ammonium and anaerobic ammonia oxidation contribution is not obvious.The concentration of nitrate nitrogen treatment group in this study is reduced from 8.55 mg L-1 to 0.96 mg L-1,and the total nitrogen concentration decreased by 8.3 mg L-1,showed that large amounts of nitrogen within the system is removed,the denitrification rate is far higher than the rate of denitrification in the literature sediments,the system of algae and bacteria have certain advantages in nitrogen removal hand. |
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