| As an important nutrient element of organisms to grow, nitrogen is one of the cause of eutrophication of water bodies.The removal of nitrogen in the sewage water treatment theory and technology is the hot spot in the research.Traditional biological nitrogen removal methods in the removal of ammonia nitrogen at the same time will waste a lot of energy,it cannot be efficient to removal of ammonia nitrogen, and shortcut nitrification and denitrification process has the advantages of energy-saving, environmental protection,high efficiency, low carbon, carbon sources and oxygen consumption can be reduced to achieve efficient denitrification. But as a result of dissolved oxygen, p H, temperature and so on various aspects factors, stability of shortcut nitrification and denitrification process is more difficult.In order to achieve the stability of shortcut nitrification and denitrification, this experiment adopts SBR reactor, using artificial simulated domestic sewage as the reactor inlet, using aerobic/anoxic operation mode, by controlling the inlet concentration of ammonia nitrogen and oxygen,with real time control of the DO concentration and timely stop aeration way, shortcut nitrification and denitrification is implemented.Test are at room temperature, that is, 25 ~ 30 ℃, retrieved from sewage plant sludge domesticated first, make it restore activity and gradually enriched nitrobacteria,test water quality of COD is 220 mg/L, ammonia nitrogen is 30 mg/L, orthophosphate is 5 mg/L, using the mode of into the water- aeration and stirring-precipitation- drainage, after 30 days of sludge domestication, reactor effluent COD concentration to 20.0 mg/L, ammonia nitrogen fell to 0.6 mg/L, nitrate nitrogen accumulation to 21.5 mg/L. Test into the startup phase, control water p H at 8.0 ~ 8.5,with the mode of into the water- aeration and stirring(real-time control)- stirring-precipitation- drainage. Startup phase of the accumulation of nitrite nitrogen was divided into four phases: the first phase control DO in 2 ~ 3 mg/L, ammonia nitrogen of 30 mg/L, the second phase control DO in 2 ~ 3 mg/L, ammonia nitrogen of 50 mg/L, the third phase control DO below 1 mg/L, ammonia nitrogen of 50 mg/L, the last phase control DO below 1 mg/L, ammonia nitrogen is 70 mg/L, after four stages of selection and cultivation, eventually the reactor effluent ammonia nitrogen concentration was only 2.0 mg/L, the removal rate of 95 % above, aerobic period of nitrite nitrogen accumulation to the end of 22.3 mg/L, accumulation rate was 91.7 %, and the nitrate nitrogen was only 2.0 mg/L, almost suppressed. at this point, shortcut nitrification and denitrification is implemented, so to speak.Experiment discussed the shortcut nitrification and denitrification process stable cycle transformation regularity of inorganic nitrogen and the change of DO,p H on shortcut nitrification denitrification stable cycle were studied, the study found that at the end of the nitrification process, there is always an obvious phenomenon of sudden change of p H value and the DO, so through the change of p H and DO curve, the nitration reaction control at the end of the nitrosation stage in time, to avoid further oxidation of nitrite, can reasonable control air at the same time, more cost savings in the practical engineering application.For fast real-time monitoring of shortcut nitrification and denitrification in the process of the change of the inorganic nitrogen, the test also studied a fast measurement, it can effectively solve the problems of traditional chemical method such as need a lot of chemical reagents, easy to produce secondary pollution, tedious operation,long testing time and reaction, it is the near infrared spectral analysis technology combined with chemometrics to implement of ammonia nitrogen, nitrite nitrogen concentration of quantitative monitoring.Test of near infrared spectral preprocessing methods on the basis of the comparison, the first derivative and second derivative, standard normal transformation, multiple scattering correction, wavelet denoising method of spectrum pretreatment, i PLS method to establish quantitative analysis model respectively, based on the investigation to the model of decision coefficient and the root mean square error can be concluded that wavelet denoising method for ammonia nitrogen, nitrite nitrogen quantitative model is the optimal spectral preprocessing methods. For the optimal quantitative analytical model of ammonia nitrogen and nitrite nitrogen, the experiment using three different combinations of modeling method, the principal component analysis combined with PLS method, wavelet denoising combining i PLS method, genetic algorithm combined with BP neural network, to establish the shortcut nitrification and denitrification process of ammonia nitrogen, nitrite nitrogen, the model of quantitative analysis of the test results show that the use of genetic algorithm combined with BP neural network model have the optimal effect, calibration of ammonia nitrogen determination coefficient of 0.9459, the root mean square error correction(RMSECV) is 0.0174, predict determination coefficient is 0.9542, predict root mean square error(RMSEP) of 0.0442; Nitrite nitrogen calibration determination coefficient of 0.9562, the RMSECV of 0.0155, predict determine coefficient is 0.9336, RMSEP is 0.0511, the model have very good prediction in the process of shortcut nitrification and denitrification of ammonia nitrogen and nitrite concentrations.Test of shortcut nitrification and denitrification in the process of rapid determination method of inorganic nitrogen research provides a theoretical basis for real-time monitoring,provides a feasible analysis technology for the rapid determination of inorganic nitrogen, is of great significance to practical application for sewage plant. |
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