Optimization Control Strategies For The High Efficiency Approaches Of Biological Nitrogen Removal In Sequencing Batch Biofilm Reactor

The present-day wastewater treatment practices can be significantly improvedthrough the introduction of new microbial treatment technologies. Recently, severalnew processes for nitrogen removal have been developed. These new nitrogenremoval technologies provide practicable options for treating nitrogen-ladenwastewaters. The new processes are based on partial nitrification of ammonium tonitrite combined with anaerobic ammonium oxidation. These processes include thesingle reactor system for high ammonia removal over nitrite (SHARON) process,which involves part conversion of ammonium to nitrite; the anaerobic ammoniumoxidation (ANAMMOX) process, which involves anaerobic ammonium oxidation;and the completely autographic nitrogen removal over nitrite (CANON) process,which involves nitrogen removal within one reactor under oxygenlimited conditions.These new processes target the removal of nitrogen from wastewaters containingsignificant quantities of ammonium.In this paper, the research findings and up-to-date research progress in here andabroad were introduced. It pointed out the importance of developing biologicalnitrogen removal in our country, and summarized the problems in the recent research.Furthermore, the developing trends of the technology were discussed in the end.First, it was studied and analysed on the mechanism on the nitrogen removalwhen treating the leachate with highly concentrated ammonia and nitrogen bysequencing batch biofilm reactor(SBBR) designed by ourselves. Under the ambienttemperature of (32±0.4)℃, and after a 58-day-long period of domestication and a33-day-long period of stability, the ammonia nitrogen removal efficiency reached95% in the SBBR reactor. The way of high frequency micro aeration suppresses theactivity of nitrobacteria, and also eliminates the influence of nitrous acid and pHundulation to the activity of anaerobic ammonia oxidation bacteria and nitrous acidbacteria. In the period of aeration, the dissolve oxygen concentration was controlled at1.2~1.4 mg.L-1; the nitrous acid bacteria became the majority , and nitriteaccumulated. In the period of hypoxia, along with the debasement of the dissolveoxygen concentration, anaerobic ammonia oxidation bacteria became the majority, nitrite and ammonia nitrogen accumulated in the period of aeration was removed atthe same time.Second, the conventional microorganism techniques and the molecule biologicaltechniques such as PCR and DGGE were utilized to study the approaches ofbiological nitrogen removal in a single sequencing batch biofilm reactor (SBBR). Inthis study, the main approach of biological nitrogen removal, no less than 65% of thetotal NH4+-N was removed in this approach, was composed of partial nitrification,anaerobic ammonium oxidation and denitrification, the second approach includedtwain processes such as partial nitrification and denitrification, and the third one wasconventional nitrogen removal process (nitrification and denitrification). Allapproaches accomplished by the way which the processes carried on simultaneous orasynchronous. When the approach occurred in the simultaneous way, it performed asnitrogen-loss. The accomplisher of asynchronous way depended on the microbe'sdifferent activity between aerated phase and anaerobic phase. First, ammonia wasconverted to nitrite in the aerated phase when the nitrite bacteria performed highlyactivity, and then anaerobic phase was operated in turn when the denitrifying bacteriaand the anammox bacteria eliminated the nitrogen form gases.In addition, in view of economization of the running cost, under three differentkinds of low temperature domestication strategy, three sets of the anaerobic sequencebiofilm reactors (ASBBR) with the same specification were applied. The traditionalanalytical method was used to analyse the nitrogen change in the process of operation,simultaneously techniques of denaturing gradient gel electrophoresis (DGGE) wasalso used to analyse the species group structure on the biofilm, and the activity ofanaerobic ammonia oxidation under different low temperature domestication strategywas preliminary investigated. The result showed that corresponding to the threedifferent kinds of low temperature domestication strategy: al, a2 and a3, A1, A2 andA3 showed different anaerobic ammonia oxidation activity after domestication in 62d,56b, and 70d respectively. Taking the nitrogen transformation efficiency as ameasurement criteria, its activities from high to low in turn are: A3﹥A1﹥A2. TheDGGE analysis further explained that under different domestication strategies thereactors would display different specie-diversities, but the population structuremaintained almost the same. And in the strategy with the same inoculums, it had the uniformly influence to the population diversity and the anaerobic ammonia oxidationactivity produced by the temperature decreasing range.