| Nitrogen is a class of important pollutants,which harm to human health and environment.The presence of nitrogen is mainly organic nitrogen and inorganic nitrogen.However,due to the participation of various denitrification in the various flora of nutrients and dissolved oxygen requirements are different,which produced nitrogen removal process complex.and it largely limits its application in practical engineering.In the previous study,we found that the bio-sponge iron system had better nitrogen removal effect than the ordinary activated sludge system,and found that there were a lot of iron bacteria and aerobic denitrifying bacteria in the bio-sponge iron system.The effect of sponge iron and NO3--N on the treatment efficiency of SBR reactor was investigated in this paper.And its effect on the number of microbes(iron bacteria and aerobic denitrifying bacteria).The aerobic denitrifying bacteria with iron oxidation function in each reactor were separated and screened,and One of the highly efficient denitrification ability of aerobic denitrifying bacteria 2-5 for physiological and biochemical and 16 Sr DNA identification.The effects of carbon source,C / N,sponge iron dosage,initial p H value and temperature on the growth characteristics and denitrification performance of aerobic denitrifying strain 2-5 were investigated.At the end of this paper,we carried out the study of2-5 strain to strengthen ordinary SBR reactorResearch indicates:(1)The effect of adding sponge iron and NO3--N SBR reactor(biological sponge iron system)was better than that of ordinary activated sludge system.The former TN removal rate of 33.54 mg / L is about 2 times the amount of TN removal.The determination of iron bacteria and aerobic denitrifying bacteria in each reactor confirmed that sponge iron and NO3--N could promote the speculation of the growth of iron bacteria and aerobic denitrifying bacteria in the system.It is precisely because of the large presence of such microorganisms that promotes the degradation of TN by SBR reactors.(2)19 aerobic denitrifying bacteria were screened,Through the separation and screening of aerobic denitrifying bacteria in three SBR reactors.The results showed that the strain 2-5had the best effect,The NO3--N decreased from 126.79 mg / L to 37.12 mg / L and the removal rate was 70.72% at 48 h after culture.NH4 +-N remained at a low level during the whole process.The physiological and biochemical experiments and 16 S r DNA analysis of strains 2-5 showed that 2-5 belonged to denitrifying nonferrous bacteria and reached 99%homology.(3)When the carbon source was used to study the growth characteristics and denitrification properties of the strain,it was found that the strain 2-5 had higher growth and growth rate than the other carbon sources when methanol was used as the carbon source.At the same time,the carbon source structure was more simple,the growth rate The faster.At the same time,the degradation rate and removal rate of NO3--N were the highest when methanol was denitrified electron donor,but the removal rate of TN was not the largest,and the removal rate of TN was the highest when potassium tartrate was carbon The This is mainly due to the different denitrification pathways under different carbon sources,resulting in different amounts of nitrite accumulation,resulting in NO3--N removal rate and TN removal rate on the consistency of a certain difference.At the same time,the simpler the structure of the carbon source,the faster the growth rate of the strain.(4)The effects of C / N,sponge iron addition,initial pH value and temperature on the denitrification effect of 2-5 were investigated.The results showed that the optimum C / N was17 and the sponge iron dosage was 1 g / L.The denitrifying effect(denitrification rate 59%-93%)was better for the strains 2-5 under the conditions of neutral and alkali(p H 7-9).The degradation rate of TN was 93% at the initial p H value of 7.When the temperature is 20 ?,the nitrogen removal efficiency of the strain is poor,and there is still a lot of residual.When the temperature is 30 ?-35 ?,the strain 2-5 TN removal rate can reach more than 90%.(5)The aerobic denitrifying strains 2-5 were applied to the intensification experiments of the SBR reactor.Under different NO3--N influent load,the denitrification effect of each reactor changes regularly,and this change can be improved by adjusting the C / N of the reactor.However,compared with the 4 # reactor in the whole process has a good ability to resist high nitrogen load,which may be added to the reactor with sponge iron has a close relationship.The changes of TN and NO3--N in a cycle of 4 # reactor were investigated at the same time.The experimental results show that TN and NO3--N can be degraded to a low level in a short time(240 min)at each stage of the 4 # reactor. |
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