Characters And Reduction Effect Of Nitrogen And Phosphorus Salt For Biofilm Formed On Different Bio-carrier

For the sake of revealing the biological membrane characteristics formed by different carriers as well as the removal effect of which on the nitrogen and phosphorus in water bodies, in this paper, the membrane maturation processes of the biological membranes, which are shaped by corallite, respiratory ring and biochemical cotton carriers cultured in simulated sewage made with natural seawater, are analyzed. The species and concentration of nitrogen and phosphorus are investigated during the course, and the structural characteristics of mature biofilm are further analyzed with the help of scanning electron microscope, as well as both of the effects of different types and concentrations of nitrogen and phosphorus on the organic carbon source and non-organic carbon source are compared in simulated sewage, and the bacterial community structure of the mature biofilm is analyzed by using Illumina MiSeq sequencing technology. The main results are as follows:1. During the mature period of the biofilm, both of the attachment effect and the removal efficiency of nitrogen and phosphorus are superior to those of biochemical cotton, in addition, the chlorophyll-a and extracellular polysaccharide of the corallite biological membrane are highly significant negatively correlated with the concentration of PO43--P, and the chlorophyll-a and extracellular polysaccharide in the respiratory ring are highly significant negatively correlated with the concentration of PCO43-P and NH4+-N as well.2. While treating the simulated aquaculture sewage withOTU the addition of organic carbon source by using mature biofilm, it can be seen that the NC2--N accumulation is eliminated by either the biological membrane of the corallite or the respiratory ring on the 11th day, whose removal rates of NH4+-N on the 4th day and the 5th day reach 99.05% and 99.60%, respectively, and the removal rates of PCO43-P on the 12th day reach 81.12% and 76.36%, respectively. The final concentrations of NO3--N are 3.734mg/L and 3.333mg/L after being treated by the biological membranes of the corallite or the respiratory ring, respectively; and the removal efficiencies of these two biological membranes on nitrogen and phosphorus are of no significant difference (P> 0.05). With the help of scanning electron microscope, it can be found that there exists translucent extracellular polymeric substances(EPS) and abundant algae on the surface of the corallite biological membrane, and the algae mostly belongs to diatom such as Navicula, Achnanthes, Amphora, Mastogloia, Nitzschia algae species, etc.; whereas the EPS of the surface of the respiratory ring biological membrane are fewer than that of the corallite biological membrane, and there exists a large number of diatoms but fewer species, which mainly belong to Fragilaria, Thalassiosira, Nitzschia species, etc..While treating the simulated aquaculture sewage with the addition of organic carbon source by using mature biofilm, it can be seen that the NO2--N accumulation is eliminated by either the biological membrane of the corallite or the respiratory ring on the 4th day, whose removal rates of NH4+-N on the 3th day both reached 99.05%, and the removal rates of PO43--P on the 12th day reach 73.26% and 34.95%, respectively. The final concentrations of NO3--N are 1.808mg/L and 3.457mg/L after being treated by the biological membranes of the corallite or the respiratory ring, respectively. Both of the two mature biofilms can still remove NH4+-N and reduce the content of PO43--P in the simulated aquaculture sewage effectively, which significantly improves the removal rate of the sewage compared with that of the non-added organic carbon source simulated aquaculture waste water, and the treatment effect of corallite membrane is better than that of the respiratory ring membrane. With the help of scanning electron microscope, it can be found that the surface of the corallite forms a dense biofilm, whose surface has a large number of cluster structures and some interior deepened pore structure, whereas the biofilm on the surface of the respiratory ring appears to be cracked or even fell off.3.With the sequencing completion of these two kinds of proposed simulated aquaculture sewages which has addition or non-addition of organic carbon source by using MiSeq Illumina sequencing technique, the results of rRNA 16S gene analysis show that a total of 1660 OTUs are generated, and more than 60% of which are commonly owned by the two carrier biofilms. There are altogether 28 identified bacterial phyla, including Cyanobacteria, Proteobacteria, Bacteroidetes, Planctomycetes, Acidobacteria, Verrucomicrobia and Chloroflexi, among which the Cyanobacteria is the dominant physiological flora as well as the Proteobacteria is second largest bacterial phyla only next to Cyanobacteria. The Alpha and Beta diversity analysis shows that the microbial community structure of the mature biofilm on corallite and respiratory ring can be changed as the organic carbon source is added into the cultivated water body, and whether the carbon source is added, the richness and diversity of microbial communities on the biofilm of corallite is always higher than that of the respiratory ring.