Study On The Solid-phase Denitrification Effect And Mechanism Of PBS

Utilize Biodegradable polymers (BDPs) to removal nitrate of water is a new technical, they can serve both as adhereing carrier and carbon source for denitrfying microbe,meanwhile,they can avoid of scendary pulltion which caused by liquid source and other types of solid carbon source, so they have great potential of development and research. Poly(butylene succinate) , PBS, is one kind of BDPs. To understand the effects and mechanism of PBS used in recirculating aquaculture water denitrification, This experiment studies the following aspects:Study on the Effect and Mechanism of freshwater denitrification using PBS. Using conical flask as the reaction, PCR-DGGE (Polymerase chain reaction-denaturing gradient gel electrophoresis) was also used to investigate the microbial community dynamic change of the biofilm over PBS during different operating period (5th day, 10th day, 15th day, 20th day). The results show that the NO₃^--N concentration Significantly lower after 4 days, meanwhile, the NO₂^--N concentration increased. After that the NO₃^--N concentration going down during fluctuation, meanwhile, the NO₂^--N concentration Increased and then decreased (4th day～20th day). After 20 days, the NO₃^--Nconcentration decreased below 2 mg/L and maintain stability, meanwhile, the NO₂^--N concentration decreased below the examination area. Statistical analysis of DGGE profiles showed that, with the reaction, bacterial species richness gradually increased, and the similarity of the two adjacent period increases. Coordinated with denitrification effect, the community structure of microorganism transformed in different periods and got stability in the end.β-Proteobacteria (56.25%) andγ-Proteobacteria (31.25%) were the main dominant species.Study on the Effect and Mechanism of salt water denitrification using PBS. Using conical flask as the reaction, PCR-DGGE (Polymerase chain reaction-denaturing gradient gel electrophoresis) was also used to investigate the microbial community dynamic change of the biofilm over PBS during different operating period (11th day, 21th day, 31th day). The results show that the NO₃^--N concentration Significantly lower after 7 days, meanwhile, the NO₂^--N concentration increased. After that the NO₃^--N concentration going down steady, meanwhile, the NO₂^--N concentration Increased and then decreased (7th day～20th day). After 21 days, the NO₃^--Nconcentration decreased below 0.1 mg/L and maintain stability, meanwhile, the NO₂^--N concentration decreased below the examination area. Statistical analysis of DGGE profiles showed that, with the reaction, bacterial species richness gradually increased (0.476→0.571→0.667), and the similarity of the two adjacent period increases (33.3→54.5→61.5). Coordinated with denitrification effect, the community structure of microorganism transformed in different periods and got stability in the end.γ-Proteobacteria (66.67%) andα-Proteobacteria (16.67%) were the main dominant species.Study about continuous denitrification reactor build with PBS. A continuous denitrification reactor was build to study the denitrification effect, different heights changes in microbial community of space. The results showed that when HRT control at 8 hours, the reactor water run for 2 days after the NO₃^--N concentrations began to decrease, and within 10 days from the stable at 98%, during the first 16 days only in the water NO₃^--N removal rate of doubling the concentration to make the day slightly lower (96.03%). Best nitrate removal reactor reached 99.7% (19, 24 day). At the same time, the reactor started a short time NO₂^--N concentrations increased rapidly, and the accumulation of a period of time (1 to 8 days). 9 days starting from the effluent NO₂^--N concentrations of detection range down below, and remained stable. And nitrate nitrogen is similar to the first 16 days only a temporary rise. Reactor running for 30 days, at the bottom of the reactor to reduce the quality of most PBS, 23.4%; followed by the middle of 3.7%; reduce the quality of the upper part of the smallest, only 0.2%. Stable operation of the reactor after the separation of different height of the DGGE profiles showed that the reactor there is room for differences in microbial community structure, for the loss of different positions between the quality of PBS to provide proof of the microbial level. After stable operation of the reactor, the filler particle surface SEM photos show, PBS outer surface of the bacteria in the degradation of the enzyme degradation in vivo, the formation of a multi-level pore-like structure and a large hole.