The Research On Effect Of Applying Nitrifying Biofloc To Culture Litopenaeus Vannamei

Bio-floc technology can be used to promote the sustainable development of aquaculture.The key of bio-floc technology is creating a stable microbial ecosystem to convert TAN and NO2--N efficiently.Traditionally,BFT which is through the addition of carbon sources for heterotrophic bacteria that convert TAN into bacterial protein.keeping the water quality stable and promoting the growth of aquaculture annimals.If according the C/N from 15 to 20.The addition of carbohydrate in heterotrophic biofloc systems is higher.During the whole culture period,carbohydrate which more than 40% of feed were added in system.It should be noted that without adding carbohydrate,ammonia-oxidizing bacteria(AOB)and nitrite-oxidizing bacteria(NOB)can control the concentration of TAN and NO2--N lower in nitrifying biofloc system.Therefore,The study which applied in production of Litopenaeus vannamei is important.The study on practical application of nitrifying biofloc to culture Litopeaus vannamei.The main results are as follows:1.we use nitrifying bioflocs to culture Litopenaeus vannamei in ultra high stocking density(1667 ind/m3 and 2821 ind/m3),investigating the effect of nitrifying bioflocs in the change of water quality and the growth performance of Litopenaeus vannamei,and the change of bacterial community structure and abundance.The culture period is 109 d.The results show that the dominant bacteria in nitrifing biofloc are Actinomycetes and Proteobacteria in the level of phyhum.Rich nitrify bioflocs can be maintained the concentration of total ammonia nitrogen and nitrite nitrogen are less than 1 mg/L.The concentration of Nitrate nitrogen and total suspengded solids in treatment group which stocking density is 2821 ind/m3 are more higher.The production of shrimp has nosignificant difference between treatment groups(P > 0.05)The stock denisty of 1667shrimp/m3 is very best for the growth performance of Litopenaeus vannamei.2.Rich-nitrifying biolfloc aquiculture Water(14m3)which the proportion of raceway volume is 46.7% was inoculated in new system.The initial TSS concentration of aquiculture systems was adjusted to 532 mg/L(15~22 mL/L floc volume),and stocking density of Litopenaeus vannamei is 897 ind/m3.The change of water quality and the growth performance of Litopenaeus vannamei,and the change of bacterial community structure and abundance are observated.The culture period in this study is 82 d.The results show that high concentration of bioflocs can control the concentration of ammonia nitrogen and nitrite nitrogen in lower level.The highest concentration of total ammonia nitrogen and nitrite nitrogen are not more than 0.62 mg/L and 0.5 mg/L,respectively.The abundance of nitrifying bacteria in biofloc is increasing,The maximum abundanc of nitrite-oxidizing bacteria is(3.26±1.64)%.The Survival,production,final weight of Litopenaeus vannamei are(53.04±4.57)%,(4.85±0.50)kg/m3 and(10.17±0.19)g/shrimp,respectively.Litopenaeus vannamei which was cultured in nitrify biofloc systems can get better growth performance.Nitrify biofloc can keep aquaculture water environent safety.3.The study was designed to explore the effect of different addition of carbon sources(0 g/m3/d,167.78 g/m3/d,335.56 g/m3/d)on the high nitrate water in the denitrification process.Results show that when carbon source adding,denitrification can be promoted.Adding carbon source in denitrification process shows that the change of pH is firstly descend and then ascend.Accumulation of ammonia nitrogen and nitrite nitrogen were found.Both the group of 167.78g/m3/d and 335.56g/m3/d show that nitrate nitrogen removal rate and total nitrogen removal rate is not significantly different at the end of the experiment(P>0.05).Nitrate nitrogen and total nitrogen removal rate can reach more than99.7% and 75%,respectively.But the addition of C6H12O6 is 167.78 g/m3/d which can more faster to removed nitrate nitrogen.167.78 g/m3/d or 335.56 g/m3/d as the addition of C6H12O6· H2 O can remove 151 mg/L nitrate nitrogen efficiently.High concentration of nitrate in biofloc aquaculture water can be removed through C6H12O6/initial NO3--N=1 to determine the daily addition of carbon source,which is the most economic.