Study On The Effect And Regulation Of Extracellular Polymers Of Cyanobacteria On Coagulation Process

The AOB half-velocity constant for dissolved oxygen is much lower than the NOB half-velocity constant for dissolved oxygen,and recent reports have found conflicting values as well as large material diffusion resistance inside nitrifying granular sludge and its kinetic parameters and flocculated sludge-based measurements.There are large differences in parameter values and cannot be directly applied to mathematical simulations.This experiment focused on short-cut nitrification granular sludge CSTR reactors.In the continuous flow reactor,short-cut nitrification granular sludge was cultivated.In operation,the influent ammonia nitrogen was changed,and the ammonia concentration in different mixed liquids was studied for short-cut nitrification granules.Effect of sludge denitrification.At the same time,the influence of particle size distribution on partial nitrification kinetic parameters in short-range particle reactors was explored.Both experimental and mathematical simulations have verified the effect of particle size distribution on partial nitrification kinetics in short-range particle reactors,providing theoretical guidance for better interpreting and optimizing the nitrification process ofwastewater.The main conclusions are as follows:(1)Denitrification and nitrification were very obvious on the 1st to 15th days,and nitrogen removal reached 100%.The effluent NH4+-N has reached 0,and the short-range rate is about 73%from the first 15th to the 60th day.The effluent ammonia nitrogen,nitrite nitrogen,and nitrate nitrogen in the 60th to 300th day have not changed much,and the nitrification granular sludge has been denitrified.The effect has not changed much.It is impossible to achieve the effect of short-cut nitrification and denitrification by adjusting HRT alone.Comprehensively adjusting the short-cut nitrification rate can significantly increase the denitrification effect by more than 90%in a short term.After 3 days of maintenance,the short-run nitrification rate is maintained at 80.%about.(2)In spite of the high concentration of ammonia nitrogen used in this experiment,the measured N03-concentration was also high(above 6.5 mgN/L),the particle size was 0.5 mm,and the average partial nitrification percentage range was about 70.-80%.The probable cause of low median particle size sludge diameter results in lower nitrification.(3)In nitrifying granular sludge reactors,short-cut nitrification is also achieved by high dissolved oxygen,and partial nitrification is achieved due to the internal transport of oxygen to the internal transport of the particles.(4)The nitrite accumulation in the large-sized particles(without small particles)was higher.It can be used to improve partial nitrification in nitrification particle reactors and to increase nitrite accumulation by removing NOB selectively by removing small particles.(5)The DO half-rate constants of the measured NOB and AOB were(0.22±0.02)and(0.98±0.04)mg/L,respectively.The nitrite nitrogen half rate constant and the ammonia nitrogen half rate constant were(1.50±0.02)and(3.30±0.01)mg/L,respectively.The maximum specific growth rates of AOB and NOB were(0.51 ±0.05)and(0.43 ±0.02)d-1,respectively.(6)When the AOB accounts for more than NOB in the activated sludge,the KO and AOB values gradually increase with KO and NOB as the particle size increases.The results of other studies were consistent when the activated sludge particle size was greater than 100 ?m,which explains the high dissolved oxygen half-saturation constant reported by NOB in some literature.(7)After the active granular sludge sample was broken with ultrasonic waves,the median particle size was reduced from 420um to 50um.It is obvious that the values of KO and NOB were stable at 0.2mg 02L-1.In contrast,apparently KO,AOB The value quickly decreased from 1.5 to 0.24 mg O2 L-1.The KO,AOB,and KO were measured by linear interpolation.The relative values of the NOB estimate were 0.041 and 0.19 mg O2 L-1,respectively.The results of the simulation and the results of the experiment Consistent with the model,it can be demonstrated that the large particle size and NOB ratio in the model can be used to prove the reason that the measured correlation values of KO,AOB and KO,and NOB are reversed.This experiment explained and reported the conflict between measured KO,AOB and KO,NOB related values.Mathematical simulations were performed using a biofilm model to verify the feasibility of this model for nitrification particle reactors.