Study On Optimizing High Efficient And Functional Strains And Constructing Complex Heterotrophic Nitrification-aerobic Denitrification Strain Floras

Today, heterotrophic nitrification-aerobic denitrification as one of the new biological nitrogen theory has become the focus research gradually, but the studies of gas product N₂O have been reported rarely, the studies of constructed complex heterotrophic nitrification-aerobic denitrification Strain floras have been also reported rarely. This paper selected heterotrophic nitrification-aerobic denitrification strains from the activated sludge systems of the laboratory reactor and Henan Lianhua Monosodium Glutamate Factory. To choose the incubate condition, strains were used to conduct orthogonal test in flask, then tracked determination N₂O gas product with the GC-ECD method in 2.5L fermentation pot, screened out the special features strains of N₂O control; This study selected the good performance of heterotrophic nitrification-denitrification strains, constructed environment adaptable complex floras in accordance with the growth behavior, nitrification performance of the strain.In this study, 53 bacteria were selected from sludge of A and B reactors of the laboratory as well as Henan Lianhua Monosodium Glutamate Factory, which have 25 aerobic denitrifying bacterias, 8 nitrifying bacterias, 12 nitrite bacterias, 8 biochemical strains. The nitrate removal efficiency and ammonia removal rate of ten bacteria of 25 aerobic denitrifying bacterias were both more than 50%, the ten bacterias were WYLW1-2,WYLW1-3,WYLW1-4,WYLW1-6,WYLW1-9,WYLW1-10,WYLW2-4, LH1-1, LH2-1, LH2-3, identified as heterotrophic nitrification-aerobic denitrification strains.The orthogoal experiment was used to choose an incubate condition of the ten heterotrophic nitrification-aerobic denitrification strains. WYLW1-6 and LH1-1 conducted two orthogonal experiments, in order to narrow the range of experiments, selected more precise culture conditions of strains, the remained eight strains conducted L₄ (2³) orthogonal experiment. The maximum ammonia removal rate and total nitrogen removal rate of the ten heterotrophic nitrification-aerobic denitrification strains except WYLW1-9 were over 90%. It is worth noting, ammonia nitrogen removal rate of LH1-1 was 99.87%.The results showed that the ten heterotrophic nitrification-aerobic denitrification strains can remove NH₄⁺-N,COD,TN simultaneously under the optimal conditions.WYLW1-2 and WYLW1-6 have strong adaptability. It is worth mentioned that WYLW1-2 has been achieved maximum growth at 32h, the maximum ammonia removal efficiency was 97.08%, the maximum ammonia removal rate was3.54mg / L·h, WYLW1-2 was the practical application strain .WYLW2-4 of the ten heterotrophic nitrification-aerobic denitrification strains has the maximum ammonia nitrogen removal rate,the rate was 4.71 mg/L?h and COD removal efficiency of WYLW2-4 was 91.20%. Compared to only nitrifying bacteria Bacillus sp. LY of the literature, 10 strains studied were heterotrophic nitrification- aerobic denitrification strains, 10 strains except WYLW1-9 has environment advantage in the aspect of the ammonia removal efficiency and total nitrogen removal rate and the time required for maximum growth. Compared to the heterotrophic nitrification- aerobic denitrification strain A. faecalis No.4 of the literature, the maximum ammonia removal rate of WYLW2-4 is almost the same with the A. faecalis No.4, but the time required for maximum growth of WYLW2-4 was only 75h, 18h shorter than the A. faecalis No.4, so WYLW2-4 has more environment competitive advantage than the A. faecalis No.4.WYLW1-2 and WYLW1-6 were selected to conduct N2O track test.The results showed that the two strains with N2O control of special features.Under the fermentation pot cultivation, ammonia removal efficiency of WYLW1-2, WYLW1-6 were94.56%, 97.19% respectively,but in flask were 92.40%,95.21% respectively. N2O-N amount accounted for TIN removal amount were only 0.424% and 0.598%.WYLW1-2,6,10,WYLW2-4,LH1-1,LH2-1,LH2-3 were used to build seventeen complex floras .The complex floras 1 (WYLW1-10, WYLW2-4), 4 (WYLW1-10, LH2-3), 6 (WYLW2-4, LH2-1), 11 (WYLW 1-2, WYLW 1-6), 12 ( WYLW 1-2, LH 1-1), 15 (WYLW 1-6, LH 1-1) can maintain the high ammonia and total nitrogen removal rate, were more than 90%. Two strains of Floras were no conflict phenomena between them, they can promote each other,then play the largest group advantages. The start-time of Complex floras was half of single strain.Complex floras 12 starts more quickly than single strain, can tolerate 3.5% salinity.Under the conditions of 80,120,160 mg/L ammonia concentration, Complex floras 12 have over 65% ammonia removal efficiency. The Complex floras 12 can tolerate high salinity, high ammonia concentration, it has the value of the project promotion.