Research On Methods Of Biofilm Nitrosation And Denitrification Phosphorus Removal

Compared with the other biological phosphorus removal processes, denitrification and phosphorus removal process that used nitrite as electron acceptor not only has advantages of common denitrifying phosphorus removal processe such as sludge settling properties, good phosphorus removal, sludge fertilizer high, easy to dehydration and low energy consumption but also has other advantages such as low energy consumption, carbon consumption, less sludge production and so on.In this study,to begin with, dealing the ideal raw water of non-organic carbon source and using sequencing batch biofilm reactor (SBBR) achieved domestication of nitrous acid bacteria within a month 98% ammonia nitrogen removal rate and 95.29% nitrite nitrogen accumulation rate.At the same time using simulated sewage as dealing object,in the first place,the system running under the anaerobic / aerobic alternating condition completed training PAOs in SBR.Then, in the other conditions remain unchanged , by changing the operating mode for the anaerobic / anoxic completed denitrifying phosphorus bacteria domesticated,the system, the removal efficiency of phosphate was 83.33% after denitrifying phosphorus bacteria domesticated.Upon completion of the cultivation of two types of bacteria, some properties on the two bacteria are also studied in this experiment.It turns out that temperature is not a particularly sensitive factor to realize the autotrophic short-cut nitrification. When the temperature is controlled at the range of 20 to 35℃,the system can all realize short-cut nitrification but it is the best at 30℃.DO is a critical factor in achieving short-cut nitrification; when temperature and PH are respectively the controlled is 30℃and 7.8, DO concentration at 1.5mg/L is the best to realize short-cut nitrification ammonia nitrogen removal rate and nitrite accumulation rate were separately 95.90% and 95.38%. The autotrophic short-cut system has a certain ability to withstand the organic load.When the COD added in influent is no more than 75mg/L,it does not affect the autotrophic short-cut nitrification nitrification system and the COD removal rate is 50%. PAOs belong to mesophilic bacteria the temperature is too high or too low will affect the activity of PAOs .Experimental results show that when the temperature controlled at 20℃, PAOs has the highest activity;changing the concentration ratio of NO₃^-/NO₂^- found that when the electron acceptor is all the NO₃,the phosphate removal reach up a maximum 92.95%,NO₃^-/NO₂^- within a certain range can't inhibie microorganisms,on the contray ,it can achieve considerable removal effect. However, if it beyond the capacity of micro-organisms will lead to system collapse.considering the two parameters of phosphate removal and phosphorus uptake rate find that NO₃^-/NO₂^- =3/2 is the best concentration ratio to realize denitrifying phosphorus removal. In this condition phosphate removal efficiency reaches up to 90.12%, the maximum and the average uptake rate of phosphorus are respective 16.23 mg/(L·h) and 10.01 mg/(L·h);When NO₃^- and NO₂^- are coexistence in the system,DPB gives first prioty to using NO₃^- as electron acceptor. When the concentration of nitrite in the system does not exceed 40mg/L,the higher concentration of NO₃^- and NO₂^- ,the greater denitrification rate of NO₃^- and NO₂^-. When the system used NO_x as electron acceptor and the dominant electron acceptor was nitrate,phosphate removal and NO_x consumption of average ratio in the system is 1:1.38.Finally,completed starting of continuous flow of the biofilm denitrifying phosphorus removal process, using simulation sewage was treated by a two-month commissioning, system for COD, TN and TP removal rates were 87.53%, 73.84% and 70%. the test did exploratory research for C/N impact on system, The results show that the system is running the best C / N was between 4 and 5, too high or too low C / N is not conducive to the operation of the system and affects the water quality of the treatment effect.When the NO_x in the anaerobic zone is less than 6mg/L,the removal efficiency of TP in the two-sludge system will not be affected.The impact of different concentration of ratio oxidation nitrogeon eletronic acceptors in the continuous flow on DPB depends on the proportion of NO-₂—DPB and NO-₃—DPB in the system.COD concentration in anoxic tank determined the effect of TP removal efficiency of the system,when the COD concentration is no more than 30mg/L,the system obtained the best efficiency of TP removal.