| At present, the key of the treatment of nitric wastewater(especial low C/N wastewater) is the lack of silicon source, so the effect of nitrogen removal is not very good. The best advantage of the biological nitrous nitrifying/ Autotrophic denitrifying in this dissertation is that no silicon source is needed in the process of biological nitrogen removal, this can save energy and reactor volume,simplify treatment process,reduce occupied aerea, especially the low C/N wastewater.In this dissertation, the effect of nitrous nitrifying of various low,middle,high concentration nitric wastewater with low C/N, such as C/N is less than 1 to 0.5. After comparison of various process, a optimum process—ANIS process can be drawn; A autotrophic denitrifying process is successfully started up and stable operated; ANIS nitrous nitrifying process and autotrophic denitrifying process are joining-up in series to operate, and sound nitrogen removal effect can be achieved. The activated sludge in nitrous nitrifying process and autotrophic denitrifying process are fully studied, and the characteristics of these processes in stable and acclimation stage have been drawed.Through a number of foregoing research, we can get that: (1)BR activated sludge nitrous nitrification system with low C/N low nitrogen concentration nitric wastewater can realize biological nitrous nitrifying, but it can not be long term stable. The renewal rate of sludge and suitable SRT is the key of stable nitrous nitrifying system. (2)The fundamental reason of nitrite accumulation in low concentration BR activated sludge nitrous nitrification system is that nitrogen oxidation bacteria compete out nitrite oxidation bacteria during the process of adapt to temperature,DO,pH,FA. (3)Nitrobacter can gradually acclimate to nitrous nitrifying conditions and refreshed, so the sludge should acclimation and the nitrite accumulation disappear. The bacillar flocculation is its typical characteristic. (4)High concentration nitric wastewater can realize stable nitrous nitrification by ANIS process(continually influence,intermittently decantation ), the influence and decant volume of the reactor is only half of its volume. The operation conditions is: temperature 28~300C; pH 7.5~8.5; DO 0.7~1.4mg/l; HRT 0.75d; SRT 3d; T 12h; reactor sludge load 0.11~1kgNH4+-N/kgMLSS?d. (5)When the HRT,SRT of ANIS system is 0.75d,3d can realize optimum nitrous nitrifying effect, and the ammonia nitrogen degradation and nitrifying rate is about 60% and 75%, and it can be long term stable, so the control of SRT is key. (6)The characteristics of the stable stage sludge of high concentration nitric wastewater nitrous nitrifying system is bacillar flocculation, long is about 0.25~1.6mm, width is about 0.15mm; When the sludge begin to acclimate to the nitrous nitrifying conditions, bacillar flocculation gradually dwindle and decomposition, still disperse into little flocculation. The typical characteristics of the sludge begin to acclimate is the appearance of a large number of round cores which diameter is 0.01~0.03mm, this can be reckoned as the marking of sludge acclimation. (7)The activated sludge autotrophic denitrifying BR process can realize stable operation after start-up and cultivation (mainly is endogenous denitrifying process) for 114d and the aerobic nitrifying sludge,anaerobic sludge,garden soil transudate as the inoculation sludge. The nitrogen ammonia nitrite and nitrate degradation rate of stable operation autotrophic denitrifying process are about 15～33%,65～90% and 50%. (8)In stable operation autotrophic denitrifying process, the main ratio of ∶∶ is 1∶2.8～3.6∶0.2～1.8. The removal of in the system is less than , it indicates that not only anaerobic ammonium oxidation process, but also other denitrifying process which not need extra silicon source in autotrophic denitrifying process. (9)The sludge of autotrophic denitrifying process is flocculent,dispersal,irregularity-shape, existing a number of sphaerotilus. Through microscope, the sludge exists a larg...
|
PDF Full Text Request