Effect Of Carbon Source Concentration On Denitrifying Dephosphatation In A～2/O SBR

It is not doubt that we must remove nutrient of wastewater for avoiding the eutrophication problem. In biological nutrient removal(BNR) processes, both denitrification and dephosphatation require carbon source, so, the competition for COD between denitrifiers and phosphate-accumulating organisms is occurred in BNR processess. This problem associated with COD limitation can be solved by introducing denitrifying phosphate-accumulating organisms responsible for anoxic phosphorus uptake into BNR processes.Sequencing batch reactor (SBR) has the following advantages: simple process, ideal plug flow (PF) reactor, adaptic operation, great efficiency of dephosphatation and denitrification and great sludge settling character.In this study, SBR experiments were carried out with anaerobic-anoxic-aerobic processess under variety of carbon source concentration condition. The conclusions are following:(1) In anaerobic-anoxic-aerobic processess, under the condition of C/P>23, C/N>7 and 1.5h anoxic phase, SBR has more than 90% removal efficiency of phosphorus, nitrogen and carbon. And the range of simultaneous denitrifying dephosphatation is more than 60%~70%(2) In anaerobic-anoxic-aerobic processess, under the condition of C/P>23, C/N>7 and 1.5h anoxic phase, the rate of phosphorus release and uptake have no significant charge responsible for variety of carbon source concentration, but rate of denitrifition has significant charge about it.(3) In anaerobic-anoxic-aerobic processess, for the ideal denitrifying dephosphatation, carbon source and oxygen source should not be present simultaneously.(4) In EBPR processess, Batch experimental tests under three different electron acceptors conditions, i.e. oxygen, nitrate and mixtures of nitrate and oxygen, were carried out using activated sludge cultivated in a SBR.(5) Stoichiometric calculations show that, in the A2/O SBR die required COD can be up to 30%less than for conventional aerobic phosphorous and nitrogen removal systems. And with the aerate phase becoming short, the volume of the reactor is also decreased.