Nitrogen Removal Response To Different Carbon And Nitrogen Ratio On Tolerant Strains Of High Ammonia Concentration

In order to obtain several strains which are tolerant of high ammonium concentration wastewater and could remove nitrogen efficiently,and study the effection of carbon source,carbon and nitrogen ratio,p H,temperature and rotation speed on nitrogen removal of strains in nitrogen wastewater.Seven strains?Dy,Td,Fu,NBQ,FM,Hf and Hj?,which were isolated from the sediments of the eutrophic pond in Tianjiahu Aquaculture Farm of Huarong County,Hunan Province,were added into 65 mg·L^-1 and 261.7mg·L^-1 and 523.4 mg·L^-1 and 1046.8 mg·L^-1 ammonium wastewater to screen strains which were tolerant in high concentration ammonium wastewater.According to the OD₆₀₀ and the removal percent of ammonium,Dy,Hj,Hf strains which are high ammonia concentration tolerant bacteria were screened from these 7 strains.And then,the 16 S r DNA sequence of Dy,Hf and Hj obtained 1394 bp,1355 bp and 1369 bp DNA fragment by PCR.According to 16 S r DNA sequence analysis,strains Dy,Hf and Hj were identified as Bacillus licheniformisficans,Paracoccus denitrificans and Bacillus amyloliquefaciens.Besides,the effections of carbon source,carbon and nitrogen ratio,p H,temperature and rotation speed onammonium and nitrite and nitrate removal percent in wastewater of Dy,Hf and Hj was analyzed.The effects of different carbon source,carbon and nitrogen ratio,temperature,p H and rotational speed on the nitrogen removal percent of Dy,Hf and Hj were studied.For carbon sources,the results showed that the order of utilization ability of Dy,Hf and Hj were glucose,sucrose,ethanol and sodium bicarbonate in the condition of ammonia or nitrite nitrogen or nitrate wastewater.When the glucose was added in nitrogen wastewater,there were the highest cell growth,the OD₆₀₀ value reached the peak value,and the nitrogen removal percent was 100%.The utilization of ethanol and sucrose was lower than glucose by these three strains.The removal of the sodium bicarbonate group was almost zero.When the carbon and nitrogen ratio is eight,the nitrogen has been 100% removed by Dy and Hj in nitrate wastewater.When the carbon and nitrogen ratio is sixteen,ammonia and nitrate and nitrite nitrogen were completely removed by Dy,Hf and Hj strains,besides that,the OD₆₀₀ value reached the peak.Dy and Hf and Hj were added into 261.7 mg·L^-1 ammonia nitrogen wastewater and 120mg·L^-1 nitrite nitrogen and 120 mg·L^-1 nitrate nitrogen wastewater with sufficient reductive organic carbon source.At 20 r·min^-1,the dissolved oxygen concentration of medium was low,and the three strains had slow metabolism.When the rotate speed was between 20 and 100 r·min^-1,thecell growth and nitrogen degradation rate of Dy,Hf and Hj were increased with the increasing the rotate speed of the shaker.At 100 r·min^-1 of shaking table,the inorganic nitrogen compounds can be completely removed by these three strains,and their OD₆₀₀ reached the peak.However,when the rotate speed was between 100 and 140 r·min^-1,the removal rate of inorganic nitrogen compounds by Dy,Hf and Hj were decreasing gradually with the increasing rotate speed of the shaker.When the temperature was between 15? and 25?,the bacterial growth and nitrogen metabolism of the three strains were gradually increased with the increaseing temperature.At 25?,the ammonia and nitrite and nitrate were removed 100 % by these three strains,and the OD₆₀₀ reached the peak value.When the temperature was between 25? and 35?,the cell growth and ammonia removal rate were increased with the decresing temperature.When p H was between 5and 10,ammonia nitrogen removal of Dy,Hf and Hj was higher than 73%.When p H was 4 or 7,the nitrogen removal percent of strains were significantly decreased,and the OD₆₀₀ values showed the same regularity.When p H was between 6 and 9,Dy and Hj had higher nitrogen removal percent in nitrite and nitrate wastewater,which were higher than 76%.Moreover,when p H was 7,the nitrogen removal percent eached 100% in ammonia,nitrite and nitrate wastewater.Hj strain was added into ammonia nitrogen wastewater in whichcarbon and nitrogen ratios is 4 and 16,respectively.And the difference of genes obtained by sequencing of the transcripts of Hj was confirmed by GOseq analysis.There were 1931 significant differences in gene expression enrichment in 143 GO terms.These significant differences were mainly distributed in three parts: molecular function,Process and cell composition.Such as Biological processes,cellular processes,metabolic processes,biological nitrogen synthesis,cellular components,cell parts,membranes,perinuclear cells,intracellular,extracellular regions,organelles,molecular functions,catalytic activity,binding,hydrolase activity,etc.The Hj gene was enriched into the KEGG database,and 523 differentially distributed genes were distributed in 93 metabolic pathways.Such as metabolic pathways,bicomponent systems,ABC transporters,carbon metabolism,pentose phosphate pathway,oxidative phosphorylation,and so on.The results showed that,for high ammonia concentration tolerant strains growth and metabolic,25?is great temperature,7 is optimum p H.Appropriate addition carbon source can improve the activity of these strains to degrade the inorganic nitrogen compound.When the carbon nitrogen is balance,these three strains had the maximum nitrogen removal percent.