Rapid Analysis Of Nitrogen Conversion In Polluted River By Near Infrared Spectroscopy And Functional Gene Changes

As the main pollution way of rivers,nitrogen pollution will not only lead to eutrophication of water bodies,but also lead to hidden dangers of drinking water.The nitrogen pollution of rivers in China is still serious,and the removal of nitrogen from polluted rivers is still the focus of the study.The traditional method of denitrification can not effectively remove the nitrogen in the river,and there are problems such as large consumption of human and financial resources,large energy consumption,and secondary pollution.The artificial aeration process has the advantages of less energy consumption,simple operation and easy operation Management,energy efficient,does not cause secondary pollution and other advantages,which are more and more used in nitrogen removal in the polluted river.In this study,the continuous aeration-stop aeration reactor was used to control the nitrogen removal process,and the sediment and overlying water samples was collected from actual polluted river.The reactor simulates the actual river conditions,The ratio of sediment to water is 1: 3,the bottom is made of light avoidance,in the continuous aeration cycle,overlying water dissolved oxygen control in 5.5 mg/L,the aeration is stopped when the nitrite nitrogen accumulation to the highest,and operates at room temperature(about 25?).During the whole operation,both the short-range nitrification and denitrification reaction occurred in the reactor,and the whole nitrification and denitrification reaction occurred.The total nitrogen in water samples collected from the river were 31.92mg/L,ammonia nitrogen was 29.00 mg/L,nitrate nitrogen was 0.49 mg/L,and nitrite nitrogen was 0.02 mg/L.The reactor was operated for 125 days.Finally,the total nitrogen was 0.88 mg/L,the removal rate was 98.90%,the ammonia nitrogen was 0.61 mg/L,the removal rate was 99.23%,and the effluent water quality was up to the third class water quality standard of surface water.The nitrogen removal of overlying water of polluted river has been realized better.The wavelet transform method is used as the preprocessing method of raw water near infrared spectrum,then combined with partial least squares method,interval partial least square method and the combination of interval partial least squares method were established for quantitative total nitrogen,ammonia nitrogen,nitrate nitrogen,nitrite nitrogen and based on the correlation coefficient r and the root mean square error RMSECV,the effect of the model was compared and evaluated.The results of near infrared spectrum pretreatment show that the interference information in the original spectrum is removed effectively.The results show that the optimal model of quantitative analysis of four indexes for the combination of interval partial least squares quantitative model,the correlation coefficient of calibration of total nitrogen was 0.9873,the root mean square error of calibration was 3.1586,correlation coefficient of prediction is 0.9458 and the root mean square prediction error was 5.2623.The correction correlation coefficient of ammonia nitrogen is 0.9828,the corrected root mean square error is 3.9188,the prediction correlation coefficient is 0.9633,and the prediction root mean square error is 4.5406.The correction correlation coefficient of nitrate nitrogen was 0.9828,the corrected root mean square error was 2.9206,the prediction correlation coefficient was 0.9363,and the root mean square error was 3.7404.The corrected correlation coefficient of nitrite nitrogen was 0.9475,the corrected root mean square error was 1.7867,and the predictive correlation coefficient was 0.9036.The root mean square error was 0.5818.The model can predict the total nitrogen,ammonia nitrogen,nitrate nitrogen and nitrite nitrogen in the overlying water of the river quickly and accurately.Microorganisms play an important role in the process of water restoration and nitrogen cycling.While denitrification is the main way to remove inorganic nitrogen in the river,so explore the repair changes of total bacteria and denitrifying bacteria in the polluted river treatment process for river water to provide a strong basis for the biology.The abundance of total bacteria and denitrifying genes nir K,nir S and nar G in the sediment during the operation of the reactor was detected by fluorescence quantitative PCR.The results showed that their abundance ranges were 1.89×109~1.22×1012 copies/ng,6.54×105~4.80×107 copies/ng,2.19×106~8.77×107 copies/ng,2.79×107~2.84×108 copies/ng.In the process of changing from anaerobic state to aerobic state in the reactor,the total number of bacteria and denitrifying genes appeared slightly reduced.This is because the lower the original dominant denitrifying bacteria and nitrifying bacteria activity,not yet grown in large numbers,and the total number of bacteria increased gradually and tends to be stable,while the number of denitrification functional bacteria decreased and tended to be stable.During the transition from aerobic state to anaerobic state,the total bacterial count decreased slightly,while denitrifying bacteria gradually increased and tended to be stable.The end of the reaction,the total number of bacteria and denitrifying genes and raw sludge in sediment samples compared appeared to reduce,this may be because after the reaction period,to eliminate a part of bacterial adaptation ability.The results showed that denitrifying bacteria existed in both aerobic and anaerobic conditions,and of the three denitrifying genes studied,the nar G gene accounts for the highest proportion,thus suggesting that the denitrifying bacteria represented by the nar G gene may be the major functional bacteria in the denitrification process.The method of rapid determination of nitrogen in artificial aeration process is studied.It provides an accurate and fast technical scheme for rapid determination of nitrogen in rivers,and has some practical significance.In addition,the changes of total bacteria and denitrifying genes in the process of artificial aeration were studied,which provided a biological basis for the process of artificial aeration treatment in polluted river.