Process evaluation of alternating aerobic-anoxic process applied in SBR for nitrogen removal
SBR工艺交替硝化反硝化运行方式的可行性研究

Feasibility of alternating aerobic-anoxic process (AAA process) applied in SBR system for nitrogen removal was investigated. Under the sufficient influent alkalinity, AAA process did not have an advantage over one aerobic-anoxic (OAA) cycle on treatment efficiency because microorganism had an adaptive stage at alternating aerobic-anoxic transition, which would prolong the total cycling time. On the contrary, AAA process made system control more complicated. Under the deficient influent alkalinity, when compared to OAA, AAA process improved treatment efficiency and effluent quality, and NH4+-N in effluent reached the detection limitation. In the nitrification, the average stoichiometry between alkalinity consumption and ammonia oxidation is calculated to be 7.07mg CaCO3/mg NH4+-N. In the denitrification, the average stoichiometry between alkalinity production and NO3--N reduction is about 3.57mg CaCO3/mg NO-N. As a result, half of the alkalinity previously consumed during the aerobic nitrification can be recovered during the subsequent anoxic denitrification period. That was why the higher treatment efficiency in AAA process was obtained without the supplement of bicarbonate alkalinity. If the lack of alkalinity in influent was less than 1/3 of that needed, there is no need for external alkalinity addition and treatment efficiency was same as that under the sufficient influent alkalinity. Even if the lack of alkalinity in influent was more than 1/3 of that needed, AAA process was an optimal strategy because it reduced the external alkalinity addition and saved the operational cost.