Effcet Of Carbon Source On Biological Nutrient Removal In Static/Oxic/Anoxic Sequencing Batch Reactor(SOA-SBR)

The environmental quality has deteriorated rapidly with the economy bloomedrapidly in China,. as with water pollution, the disorderly discharge of wastewaterwith nitrogen, phosphorus caused serious eutrophication. meanwhile people’sexpectations for environmental quality gradually augmented as their livingstandards improved, and they will pay more attention to the water quality which wasclosely related with people’s life. Therefore, the discharge standards of the nutrientspollution, nitrogen and phosphorus, in the sewage become more and more stringent.And a more higher requirement raised on the sewage treatment technology. In theprocess of wastewater treatment we should not only have high-efficiency removal oforganic matter, nitrogen and phosphorus, but also control the disposal cost.Microbial treatment method of domestic wastewater have such advantagesas lowoperating cost, no chemical reagent addition, light degree of the secondary pollution,continuous operation, which made it become the research highlight. This experimentused activated sludge method to treat domestic wastewater as the point of departure,explored the nitrogen and phosphorus removal efficiencies of the static/oxic/anoxicregime with the post-anoxic phase. To have an excellent nitrogen removalefficiencies and taking into account carbon source demand for denitrification, anoxicphase is usually put in front of oxic phase in traditional activated sludge system. Butthis situation will cause the competition of carbon source between the microbialphosphorus removal and nitrogen removal, resulting in an adverse effect on thephosphorus removal. In this system, the anoxic phase was set behind the oxic phasein order to avoid the competition of carbon source. Moreover, the performance of thenitrogen removal efficiencies was also investigated when the system have a excellentcapacity on phosphorus removal.In this experimenta static/aerobic/anoxic sequencing batch reactor (SOA-SBR)system for simultaneous nitrogen and phosphorus removal was set up with syntheticwastewater as the research object and sodium propionate, sodium acetate/propionatesodium (1:2C/C), sodium acetate and glucose as carbon source, by. This paperexplored the efficiencies of nitrogen and phosphorus removal with different carbonsources during the long-term operation respectively, and the influence of differentcarbon sources on the nutrients removal performance of static/aerobic/anoxic system was studied.Moreover, whether the deteriorated system could be restored viathe addition of favourable carbon source was also considered. Finally, cyclicvariations of phosphorus, nitrogen and intracellular energy storage material(glycogen,polyphosphate, and polyhydroxyalkanoates (PHA)) were analyzed to speculate theimpact mechanism of carbon sources on nutrients removal.The experimental results showed that sodium propionate was the best carbonsource for phosphorus removal with96%removal efficiency, and78.3%total nitrogen(TN) removal efficiency could be achieved;92.3%phosphorus removalefficiency and81.6%TN removal efficiency was obtained with sodium propionateand sodium acetate as mixed carbon source; sodium acetate was the best carbonsource for TN removal with93.7%, and92.3%phosphorus removal efficiency couldbe achieved; However, only26%phosphorus removal efficiency and36.7%TNremoval efficiency could be achieved with glucose as the single carbon source.. Withsodium propionate, sodium acetate or sodium propionate/acetate as the carbonsource, the system could achieve a good performance on synchronous denitrificationand dephosphorization. In the stage of sodium acetate as the sole carbon source thesystem yielded the best TN removal ability.By analyzing the changes of the intracellular polymers during the typical cycle,the results indicated that PHA increased and the glycogen decreased in the staticphase. Glycogen decreased by2.09,1.59,2.17,1.48mmol-C/g-VSS respectively withsodium propionate, sodium propionate/acetate, sodium acetate and glucose as carbonsource, and the synthesis of PHA was2.57,2.28,2.74,0.07mmol-C/g-VSSrespectively. PHA was decomposed and glycogen was synthesized in the aerobicphase with the synthesized glycogen contents of1.36,1.94,2.40,1.71mmol-C/g-VSSrespectively, and PHA degradation contents were respective1.42,1.09,0.98,0.06mmol-C/g-VSS.The results indicated that the contents of PHA and glycogen had a direct positivecorrelation with denrification ability and soluble orthophosphate (SOP) removalefficiencies of the system. the maximun accumulation of glycogen content wasdetected with Sodium acetate as sole carbon source in the aerobic phase, resulting inthe best efficiency of nitrogen removal. The capacity of nitrogen and phosphorusremoval efficiency deteriorated sharply when in the stage of glucose as the solecarbon source, may be the glucose more suit fou GAOs to PAOs in the competition.Finally, by adding sodium propionate, the performance of the system has a slowrecovery, although the initial domestication is slow, but eventually restored most of nitrogen and phosphorus removal performance nitrogen and intracellular polymerswere analyzed to explore the impact mechanism of carbon sources.