| In this study,Microcystis aeruginosa and eutrophic raw water collected from Xingqing Park?Xi'an city,China?using algicidal strain J25 and R11 and nitrifying strain SYF26 to investigate the characteristics of simultaneous algae-lysing and nitrogen removal as well as the removal of nitrogen source and algae in raw water.This present work was analyzed and summarized,which the following conclusions were obtained:1.Strain J25 and R11 were identified to be species of Acinetobacter.sp and Raoultella.sp,respectively.First,the optimal conditions of algicidal strain J25 and the interaction between the three factors was analyzed by SAS software.The maximum algicidal ratio of 88.06%was predicted by RSM with an temperature of 30.46?,inoculum of 23.75%?v/v?and the Microcystis aeruginosa density of 960000 cell ml-1.Second,in the experiment of optimal denitrification conditions of algicidal bacteria R11,response surface methodology?RSM?analysis demonstrated that the maximum nitrate removal ratio was 96.06%,and optimal conditions occurred were determined to be inoculum of 13.02%?v/v?,initial pH of 6.65,C/N ratio of 7.59 and temperature of27.08?.2.When J25 and R11 were combined with other strains,using ammonia as the sole nitrogensource,fourcombinationsofJ25+SYF26,J25+SYF26+ZK2,J25+SYF26+ZK2+WG9 and R1-1+SYF26+ZK2+WG9 were observed to have a higher ammonia removal ratio.Then,when the mixture of ammonia and nitrate as nitrogen source,the of combination J25+SYF26 had higher ammonia and nitrate removal ratio and highest value were 95.70%and 95.60%,respectively.3.When the initial ammonia and nitrate concentration was 2mg/L,kinetic experiment of simultaneous nitrification and denitrification of strain SYF26 was studied under the condition of pH?5,6,7,8?,C/N ratio?3.0,4.5,6.0,7.5,9.0?and temperature?15,20?,25?,30?,35??.It is concluded that a maximum nitrification and denitrification ratio was occured under the conditions of pH of 7,temperature of 30?and C/N ratio of 7.5.During the experiment of nitrogen removal in raw water,a good removal ratio of ammonia,nitrite,nitrate,total nitrogen and TOC were acquired when the strain SYF26 were added to the raw water.The concentration of ammonia was decreased from 1.92 mg/L to 0.25 mg/L in 0120 h,which removal ratio and removal rate of ammonia were 98.75%and 0.013 mg L-1 h-1,respectively.In addition,in 096 h,total nitrogen decreased from 3.53 mg/L to 0.29 mg/L,which the removal ratio and removal rate were 91.78%and 0.034 mg L-1 h-1,respectively.Meanwhile,the concentation of organic carbon decreased from 28.56 mg/L to 5.03 mg/L,which the removal ratio and removal rate were 82.39%and 0.245 mg L-1 h-1.When 3D fluorescence test showed peak 1(?ex/?em=225/330 nm),peak 2(?ex/?em=280/330 nm)and peak 3(?ex/?em=345/420 nm),which fluorescence intensity weakened was caused by strain SYF26.Therefore,it was further explained that the strain SYF26 could use dissolved organic matters such as UV fulvic-like,protein-like and visible fulvic-like as organic carbon source for heterotrophic nitrification and aerobic denitrification in landscape water.Furthermore,the similar results was also verified according to fourier transform infrared.4.In the experiment of algicidal strain J25 with different dosing method for repair of eutrophic water bodies,direct dosing strain J25 liquid,immobilized strain J25 and immobilized strain J25 added magnetic Fe3O4 had different nitrogen source and algae removal efficiency in water.In the initial 4 d,the nitrate concentration of immobilization J25 and the immobilized J25 added magnetic Fe3O4 in water decreased from 20.60 mg/L to 1.75 mg/L and 20.62 mg/L to 0.21 mg/L,respectively,and then decreased slightly from 4 d to 7 d.The final nitrate removal ratio and removal rate of immobilized J25 and immobilized J25 added magnetic Fe3O4 were 96%and 0.1188mg.L-1h-1,100%and 0.2127 mg.L-1 h-1,respectively.In the experiment of 7 d,chlorophyll-a removal ratio of immobilized J25 and immobilized J25 added magnetic Fe3O4 were 88.56%and 88.97%,respectively.Furthermore,in the treatment of free J25cells,the nitrate and chlorophyll-a decreased from 20.66 mg/L to 2.98 mg/L and 296.23?g/L to 856.36?g/L,respectively,and final nitrate removal ratio and removal rate were85.80%and 0.1052 mg L-1 h-1,chlorophyll-a removal ratio was 65.41%.At the same time,in the control,the nitrate decreased slightly in the whole experiment process and the concentration of chlorophyll-a increased obviously from 0 to 7d,which probably due to that the nitrate was used for Microcystis aeruginosa self growth.For nitrite removal,the removal ratio and removal rate of free J25 cells,immobilized J25 and immobilized J25 added magnetic Fe3O4 were 96.32%and 0.0037 mg·L-1·h-1,100%and0.0038 mg·L-1·h-1,100%and 0.0065 mg·L-1·h-1,respectively.In the determination of SOD in algal cells,the control group,free J25 cells,immobilized J25 and immobilized J25 added magnetic Fe3O4 initial SOD activity were 5.10 U·mg-1,25.32 U·mg-1,25.03U·mg-1 and 25.55 U·mg-1.After 7 days,the SOD activity of free J25 cells,immobilized J25 and immobilized J25 added magnetic Fe3O4 were 43.80 U·mg-1,49.56 U·mg-1 and54.43 U·mg-1.Meanwhile,the SOD activity in the control group was 28.07 U·mg-1.454high-throughput sequencing analysis of microbial community structure indicated that the Acinetobacter were detected in control group,free J25 cells,immobilized J25 and immobilized J25 added magnetic Fe3O4,and their relative proportion were 1.13%,9.32%,11.56%,27.87%,respectively.In the denitrification experiment using the algae flour as the carbon and nitrogen source,the algicidal strain J25 was inoculated to HM medium containing Microcystis aeruginosa flour as carbon and nitrogen source,the nitrate concentration decreased in the whole denitrification process.In the whole process,nitrate removal ratio and removal rate were 72.36%and 0.0123 mg·L-1·h-1,nitrite concentrations remain constant in the whole process,organic carbon removal ratio was 85.56%,pH increased from 6.66 to 7.22.5.The combination of biological bed and biological membrane technology for repair of landscape water,in 028 d,biological floating bed and biological floating bed combined with biological membrane all had very good removal efficiency on nitrate,and decreased nitrate from initial 1.59 mg/L to 0.58 mg/L and 1.58 mg/L to 0.14 mg/L,respectively.After 28 d,the nitrate of two treatment keep balance,the final nitrate removal ratio of biological floating bed and biological floating bed combined with biological membrane in the whole experiment were 63.52%and 91.14%respectively.The nitrite removal ratio of biological floating bed and biological floating bed combined with biological membrane were 13.75%and 50%respectively,and the control group had a large number of accumulation.Biological floating bed and biological floating bed combined with biological membrane decreased ammonia nitrogen from 1.99 mg/L to1.30 mg/L and 2.06 mg/L to 0.25 mg/L,and the removal ratio of 34.67%and 87.86%,respectively.Total nitrogen and total phosphorus removal ratio of the biological floating bed and biological floating bed combined with biological membrane were 47.50%and88.83%,31.31%and 33.07%,respectively.The algae cells of control group and biological floating bed combined with biological membrane increased from 2012 cell mL-1 to 2832 cell mL-1 and from 2025 cell m L-1 to 943 cell mL-1.Meanwhile,in the biological floating bed,the algae cells matain unchanged.Finally,TOC of the water,first,the TOC of biological floating bed and control group increased,second,the TOC of biological floating bed and biological floating bed combined with biological membrane had a significant decrease and it decreased from 15.7 mg/L to 7.23 mg/L,the removal ratio of 53.95%.454 high-throughput sequencing analysis of microbial community structure indicated that the Acinetobacter were detected in control group,biological floating bed and biological floating bed combined biological membrane,and their relative proportion were 0.01%?2.22%?6.25%. |
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