A Study On The Effect Of Operating Parameters Changes On Denitrifying Phosphorus Removal In The SBR System

Denitrifying dephosphatation process utilizes a special kind of bacteria named Denitrifying Phosphate Accumulating Organisms(DPAO)which have the characteristics of utilizing nitrate as electron acceptor to realize simultaneous nitrogen and phosphorus removal in anoxic condition.In this way,the competition between PAO and denitrifying heterotrophs organisms is avoided. Besides,the amount of energy consuming,surplus sludge and exhaust of CO₂ can be under control and it can prevent transformation from water pollution to air pollution.In this dissertation,the author studies the effects of environmental change on denitrifying phosphorus removal by using SBR process.The conclusions are as follows:(1)The system runs stably with high efficiency of phosphorus removal in DNPA process.Experimental results shows that there exits a certain amount of DPAO in denitrifying activated sludge,which could become dominant populations by providing optimum cultivating conditions,especially of A/A/O alternative environment and proper concentration of COD,NO₃^--N,PO₄^3--P. (2)In this system,the best HRT is 60min for anaerobic,150min for anoxic and 30min for anoxic.Both in anaerobic/anoxic/aerobic(A/A/O)processes and in anaerobic/ aerobic / anoxic(A/O/A)processes,induced DNPA does not disappear.(3)A lower COD concentration in the anoxic stage is profitable.In the initial anoxic stage,when the COD concentrations are 0mg/L,20mg/L,40mg/L and 60mg/L respectively,the PO₄^3--P concentration in the outflow are 0.36mg/L, 1.03mg/L,4.11mg/L,6.62mg/L。(4)Generally,a lower NO₃^--N concentration in the anaerobic stage is profitable.In anaerobic/anoxic/aerobic(A/A/O)processes,when the NO₃^--N concentrations in anaerobic initial stages are 1.41mg/L,2.62 mg/L,15.27 mg/L and 23.43mg/L,respectively,the PO₄^3--P concentrations in the outflow are 0.22 mg/L,2.86 mg/L,11.50mg/L and 9.83mg/L。The results of two-sludge SBR process used in treating domestic waste water showed that:(5)After acclimation,the two-sludge SBR system which is cultivated in laboratory can be used in domestic waste water treatment.(6)Because domestic sewage contains a lot of organic compound with high concentration and indissoluble colloid,When the anaerobic HRT of the two sludge process is 120min,the system still runs in a good situation.When the anaerobic HRT is cut to 60min,it still have a good result of phosphorus release, However,because of some COD remains in anoxic process,the effect of phosphorus removal become weaker than before.