Study On Activated Sludge Phosphorus Removal Kinetic

With the development of industry and agriculture, increase of population, water resource is absent severely and also polluted by multi-origins.The pollution of wastewater to water resource has caused extraordinary attention of the people. Activated sludge process was adopted widely in wastewater disposal,which could remove most organic contaminants and could remove partially nutriments as nitrogen and phosphorus. Rudimental nitrogen and phosphorus entered water body along with outflow, bringing harm to environment because forming eutrophication. So that nitrogen and phosphorus removal of wastewater has become prevalence and difficulty.Home and abroad present study situation of nitrogen and phosphorus removal was combined with mechanism of biological phosphorus removal, and the activated sludge of phosphate-accumulating organisms(PAOs) accounting for predominance was domesticated, then activated sludge phosphorus removal was studied in the dissertation. The effects of actiatved sludge phosphorus removal were studied, including BOD5 load,anaerobic time, pH value, anaerobic and aerobic alternate frequency, temperature and so on. Diversified working status data of activated sludge phosphorus removal were processed, Anaerobic phosphorus release models, aerobic phosphorus absorb models, activated sludge population growth model and phosphorus removal kinetic models were achieved. After experimental study, measure of actived sludge high-powered phosphorus removal was analyzed. The results were as follows:(1) Anaerobic and aerobic alternate environment is necessary condition to activated sludge phosphorus removal. PAOs could become preponderant bacterium of activated sludge after 15 days domestication. The phosphorus removal rate could above 95% when influent phosphorus is 8 mg/L and dissolved oxygen being controlled below 0.2 mg/L in the anaerobic phase and about 2.0 mg/L in the aerobic phase.(2) The concentration of easy decomposed organic substances of wastewater could affect phosphorus removal. Generally, the total phosphorus removal rate increases along with BOD5 load, ample decomposed organic substances accelerates to phosphorus release availably of PAOs in the anaerobic phase. If BOD5 load is too high, glycogen-accumulating organisms(GAOs) become preponderant competition, which could reduce phosphorus removal effect. (3) The influent water is in favor of activated sludge phosphorus removal when it is neutral or alkalescent. When influent water pH value is 6, the phosphorus of wasterwater releases largely and rapidly, the cells autolyzes in the condition of acidic water, that could affect phosphorus removal. When influent water pH value is 9, it appears phosphorus absorb then appears phosphorus release, phosphorus release is restrained obviously.(4) If Anaerobic and aerobic alternate frequency is enhanced, PAOs is preponderant growth, which could improve phosphorus removal effect. But if enhance continued aerobic alternate frequency, the phosphorus removal effect changes little.(5) In the definite range, the reactive speed quicken along with temperature, the phosphorus removal rate is also enhanced, but the phosphorus removal rate is not increase always with temperature. 20℃is perfect for activated sludge phosphorus removal.(6) Anaerobic phase phosphorus release models of diversified activated sludge working status were achieved:ΔP = a (1 ? e?kt), a and k were determied, a is the anaerobic phase balance constant of activated sludge phosphorus release, unit is mg/L; k is the anaerobic phase speed constant of activated sludge phosphorus release, unit is h-1.(7) Aerobic phase phosphorus absorb models of diversified activated sludge working status were achieved: P = ae ?kt+ b, a , k and b were determied, a is the aerobic phase saturated constant of activated sludge phosphorus absorb, unit is mg/L; k is the aerobic phase speed constant of activated sludge phosphorus absorb, unit is h-1; b is the aerobic phase balance constant of activated sludge phosphorus absorb, unit is mg/L.(8) The population growth of activated sludge phosphorus removal was studied, live bacterium amount were determined adopting phospholipids means, population growth model of activated sludge was achieved: t 1a rtNK=+ e ?K is the environment acceptance number, unit is one; a is the parameter of population growth, it's value lies on N 0; r is the population growth instantaneous speed constant, unit is d-1. The population growth model parameters as: K is 83.2383×108, a is 6.0808, r is 1.7886d-1.(9) The data of activated sludge phosphorus removal were processed. The phosphorus removal speed and total phosphorus concentration values were obtained. The data were regressive fitted, then the kinetic models of activated sludge phosphorus removal were achieved:k , K and X were determied, k is the speed constant of activated sludge phosphorus removal, unit is d-1; K is the balance constant of activated sludge phosphorus removal, unit is mg/L; X is the live component concentration of activated sludge phosphorus removal, unit is mg/L.(10) The measues of activated sludge high-powered phosphorus removal was analysed from the influencing factors of biological phosphorus removal such as anaerobic status, anaerobic time, regurgitant sludge, sludge resident time, carbon source and wastewater quality et al.There are 56 figures, 79 tables and 136 references.