Study On Removal Of Nitrogen From Low Carbon Municipal Wastewater By Solid Carbon Source Biofilm SND

At present,the form of water pollution in China is still grim,and the excess of nitrogen content is one of the main causes of water pollution.With the development of social urbanization,urban sewage presents a trend of low carbonization,resulting in the difficulty of nitrogen removal in sewage treatment plant and the difficulty of improving nitrogen removal rate.The national demand for the"emission reduction"of the urban sewage plant is increasing,so it is the main problem that the removal of nitrogen from the low carbon sewage is the face of the renovation of the sewage plant.At present,the solution to the shortage of carbon source in most urban sewage plants is to add liquid carbon source,but in the long run,the shortcomings of the liquid carbon source have been found.For example,adding quantity is not easy to control,has certain toxicity,high cost and so on,so it is urgent to seek a suitable carbon source to solve this problem.Solid carbon source has the advantage?no poison and low price?that liquid carbon source is incomparable.Therefore,solid carbon source is attracting more and more attention.At china and abroad,the technology and theory of solid carbon source nitrogen removal are also actively studied.The research is to use the silk Luffa Sponge collaterals as the biofilm carrier and solid carbon source of SBBR,and the application of synchronous nitrification and denitrification?SND?technology in the treatment of low carbon sewage in southern cities.Under the condition of normal temperature experimental study on starting characteristics of Luffa Sponge solid carbon source reactor;filling ratio,DO,water pH value,C/N value and aeration time of five factors on the effect of nitrogen removal;establish the statistical model of nitrogen removal efficiency were optimized by RSM method;finally the solid carbon source for biological membrane nitrogen removal mechanism was discussed.The results show that the Luffa Sponge static carbon emission reached the maximum at41h,carbon release process accords with the two level dynamics;Luffa Sponge extract concentration of heavy metal ions in accordance with the relevant state standards;the reactor at the start of the twenty-first period,COD_Cr,NH4⁺-N,TN removal rate was above 70%,the solid carbon source for biological the membrane of simultaneous nitrification and denitrification?SND?system started successfully;SOUR,SNR and SNUR can reach0.92mg·?L·min?^-1,8.52mg·?L·h?^-1and 5.66mg·?L·h?^-1 respectively,indicating that the bioreactor can be started quickly and the activity of the biofilm is high.Therefore,the silk Luffa Sponge collaterals are suitable as solid carbon source and biofilm fillers.In factor test,it was found that nitrogen removal efficiency can meet the first level A standard of effluent quality of sewage treatment plant when filling rate is about 40%,DO is 4±0.2mg/L,influent pH value is 7.5±0.2 and reaction time is 9h.RSM model optimization results show that DO is 4.09mg/L,influent pH is 7.58,and aeration time is 10.48h,the maximum value of theoretical TN can be reached to 86.27%.The results show that the difference between the actual removal rate of TN and the theoretical removal rate of the model is only 0.58%under the optimized condition.Electron microscope observation showed that the surface of Luffa Sponge can be attached to biofilm with a certain thickness.The attached microorganisms can get carbon source by decomposing Luffa Sponge network.In the process of denitrification,Luffa Sponge can continuously provide carbon source and improve nitrogen removal efficiency.Through the above test results,it is proved that Luffa Sponge tree is an excellent solid carbon source and biofilm carrier,which can achieve SND process well,which is suitable for low carbon urban sewage treatment.At the same time,it also provides a new solution for the treatment of low carbon municipal sewage by solid carbon source.