Study Of Low C/N Domestic Sewage In Nitrogen Removal Effection By A Sequencing Batch Biofilm Reactor

Nitrogen removal is a hot spot in the wastewater treatment. Deficiency of carbon source for denitrification has been a significant factor limiting biological nitrogen removal in wastewater treatment plant. Low C/N of domestic wastewater treatment using traditional biological nitrogen removal process is difficult to achieve emission standards. Integrated reactor SBBR process solves a lot of decreased activity problems when mixed culture of a variety of microorganism due to the environment, and offers a new way and methods for denitrification technology. This experiment is intended to take advantage of SBBR technology, combined with simultaneous nitrification and denitrification theory to research SBBR system processing low C/ N of domestic wastewater's denitrification performance in order to promote its application in practical engineering.Simulate Low C/N of domestic sewage was uesd as object in this test, with polypropylene fillers as the carriers, in the anaerobic/aerobic (A/O) operation mode, to study the influent ammonia loading,C/N ratio,the dissolved oxygen concentration on the impact of SBBR reactor in order to find the best operating parameters?In the absence of lacking of influented carbon source, Adding external carbon source, for instance, glucose, sodium acetate, corn cobs, etc. Researching the external carbon source's influences of nitrogen removal characteristics of SBBR reactor for treating low C/N of sewage.Nitrifying bacteria in SBBR reactor was successlly cultured by the way of intermittent aeration after 38d. A layer of thick biofilms had grown on the polypropylene fillers.The average removal rate of COD, NH4+-N, TN in the SBBR system had reached 77.03%,92.93%,41.41%. And get the best run cycle of the A/O operation mode:anaerobic stirring (including water time) 90min-aerobic 300min-precipitation 30min-drainage 5min-standby 55min.Through researching the influencing factors of SBBR denitrification systems in the A/O operating modes,we know that, DO at 3.5 mg/L or so, SBBR ran best, and the average removal rates of COD and TN was 95.31% and 83.71%; when the C/N ratio of SBBR system was in the range of 3 to 13, the removal rate of COD, NH4+-N and TN was 92.65%,90.47% and 66.26%, which achieve the first class level A standard of the national emission. However,when the C/N ratio of SBBR system was lower than 2.7, the later reaction came down due to lack of carbon source and then stalled. Running reactor in the optimal conditions that controled influent at pH at around 7, DO at 2?4 mg/L, the temperature of 24 ?, influent C/N ratio between 3 to 7. As a result of that, the average of effluent removal rate of COD, NH4+-N, TN was 94.56%,94.96%, 74.41%, and the effluent still achieve the national emission first class level A standard.Controlling the C/N of the experiment influent less than 2 lead to the shortage of carbon source denitrifying the process can not proceed. Adding glucose, sodium acetate or corn cobs as external carbon source at the end of anaerobic stage and the initial aerobic phase to take the comparative tests. The results of the tests showed that, after added the glucose as external carbon source, the removal rate of COD, NH4+-N and TN can reach to 95.67%,99.00% and 75.32% when the C/N rose to 4.57; after added the sodium acetate as external carbon source, the removal rate of COD, NH4+-N and TN can reach to 94.85%,99.37% and 72.33% when the C/N rose to 3.48; after added the corn cobs as external carbon source, the removal rate of COD, NH4+-N and TN can reach to 91.67%?78.12% and 77.28% when the C/N rapidly rose to 12.38. After 14d domestication of corn cobs, the results showed that the corn cobs carrier not only can precipitate a large number of COD but also appropriated microbial biofilm growth, and the test results also showed that adding 12 polypropylene carriers's simulation SBBR reactor ran the best, the average removal rate of COD and TN was 89.89% and 79.60%. These test results show that as long as a small amount of additional external carbon source, removal nitrogen objectives can be achieved.SBBR system can effectively overcome the shortcomings of traditional removal process and deal with low C/N ratio of urban sewage, a unique three-tier structure of polypropylene play a important and significant role in promoting the growth of different microorganisms, and ite denitrification is ideal. Effluent water quality have reached the the first class level A standard of "urban sewage treatment plant pollutant discharge standards" (GB18918-2002).