Study On Enhance Wetland By Biofilm Floating Bed To Remove Nitrogen From Industrial Tail Water

Tail water of sewage treatment plant refers to the effluent discharged in accordance with the discharge standard of urban sewage treatment plant after being treated by various processes of sewage treatment plant,but not meeting the requirements of the environmental quality standard of surface water and have certain environmental risks,among which the removal of total nitrogen(TN)is a prominent problem.Ecological floating bed technology has been widely used to strengthen the restoration of lakes,rivers,reservoirs,wetlands and other water bodies due to its advantages such as low occupation,low cost of operation management,good repair effect,friendly ecological environment and so on.The traditional ecological floating bed only uses the phytoremediation technology,and it is difficult for plants to grow when the enhanced wetland is used to treat the tail water of the industrial wastewater treatment plant with high salt content,and the operation effect is poor in winter.The biological contact filler suspended under the floating bed can improve the treatment efficiency of the ecological floating bed,and nitrogen in the water can be effectively removed by means of nitrification and denitrification under the action of microorganisms.Therefore,it is of great significance to study biofilm floating bed about strengthen wetland to deeply removal nitrogen from industrial tail water.In order to optimize the denitrification performance of the industrial tail water in the floating bed reactor with biological membrane,it is necessary to select the biological rope filler,synthetic fiber filler and elastic three-dimensional filler with mature biofilm,and then compare the denitrification effect of the three kinds of filler with the same filling rate and the biological rope with different filling rate on the industrial tail water.The results showed that in the static experiment of straw as carbon source,the biological rope filler with filling rate of2%was better than the biological rope filler and elastic filler with filling rate of 5%,because it is benifit to the mass transfer of nutrients and the structure center is benifit to the growth of anaerobic microorganisms.Due to its unique synthetic fiber layer,good denitrification effect,light weight,high mechanical strength and low cost,the non-porosity synthetic fiber have good engineering prospect than other fillers.By means of stimulated static and dynamic experiment of stabilization basin in tail water wetland,we compared TN removal efficiency of industrial tail water of intensified biofilm floating bed added different amount of rice straw(free additive,0.18g/L,0.54g/L)and study the problem of lose efficacy.Static experiment result shows that as increasing amount of rice straw,TN removal rate are respectivly 18%,40%and 93%.This is mainly cause by carbon source that slowly released by rice straw for supplying heterotrophic microorganism in biofilm with organic matter that can be utilized.Dynamic experiment result shows that,the mean TN removal rate of CK,T1 and T2 are respectively10%,22%and 49%when hydraulic retention time is 4d,and there are no different between infflunt and effluent with chemical oxygen demand concentration.Dissolved oxygen will decrease significantly if adding rice straw in tail water,this main reason is that carbon source released by rice straw is utilized by heterotrophic microorganism and consume DO simultaneously,and it offer an anaerobic environment that is benifit to denitrification process.Moreover,the efficacy lose of straw biofilm floating bed is due to the fact that the easily biodegradable hemicellulose material in straw is continuously degraded by the microorganisms on its surface to form small molecular organic acids such as furic acid and tryptophan for the biofilm on the surface of the filler,until the hemicellulose material is exhausted.In order to explore the effects of aeration and biological filling on the enhanced remediation of ammonia-nitrogen-contaminated tail water,three experimental groups were set up.The aeration volume of two groups were 6 L/min and 3 L/min,respectively.The volume filling rate of biological rope filling was 2%.The other group had no filling and the aeration volume was 3 L/min.Comparing the removal effects of ammonia nitrogen on the three experimental groups,combined with the changes of TN,NO3~--N,COD and DO,the results showed that the addition of biological fillers significantly increased the biomass of the system and enhanced the biological self-purification effect of the tail water,and aeration can significantly improve the utilization efficiency of heterotrophic aerobic microorganisms for difficult to use organic matter.40 strains of aerobic denitrifying bacteria with aerobic denitrifying characteristics,divided into 8 genera and clustered into 11 OTUs,were obtained by screening the culturable aerobic denitrifying bacteria on the biofilm of biological rope filler in the aerated biofilm floating bed system.The community diversity study showed that these strains in the biofilm had aerobic denitrification ability,of which Pseudomonas sp.was the most abundant strain,and Rheinheimera sp.was the second most abundant strain.