Process evaluation of an alternating aerobic-anoxic process applied in a sequencing batch reactor for nitrogen removal |
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Authors: | Zeng Wei Peng Yongzhen and Wang Shuying |
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Institution: | (1) Department of Environmental Engineering, Beijing University of Technology, Beijing, 100022, China |
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Abstract: | In order to improve the nitrogen removal efficiency and save operational cost, the feasibility of the alternating aerobic-anoxic
process (AAA process) applied in a sequencing batch reactor (SBR) system for nitrogen removal was investigated. Under sufficient
influent alkalinity, the AAA process did not have an advantage over one aerobicanoxic (OAA) cycle on treatment efficiency
because microorganisms had an adaptive stage at the alternating aerobic-anoxic transition, which would prolong the total cycling
time. On the contrary, the AAA process made the system control more complicated. Under deficient influent alkalinity, when
compared to OAA, the AAA process improved treatment efficiency and effluent quality with NH4
+-N in the effluent below the detection limit. In the nitrification, the average stoichiometric ratio between alkalinity consumption
and ammonia oxidation is calculated to be 7.07 mg CaCO3/mg NH4
+-N. In the denitrification, the average stoichiometric ratio between alkalinity production and NO3
−-N reduction is about 3.57 mg CaCO3/mg NO3
−-N. As a result, half of the alkalinity previously consumed during the aerobic nitrification was recovered during the subsequent
anoxic denitrification period. That was why the higher treatment efficiency in the AAA process was achieved without the supplement
of bicarbonate alkalinity. If the lack of alkalinity in the influent was less than 1/3 of that needed, there is no need for
external alkalinity addition and treatment efficiency was the same as that under sufficient influent alkalinity. Even if the
lack of alkalinity in the influent was more than 1/3 of that needed, the AAA process was an optimal strategy because it reduced
the external alkalinity addition and saved on operational cost.
Translated from Acta Scientiae Circumstantiae, 2004, 24(4): 576–580 译自: 环境科学学报] |
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Keywords: | alternating aerobic-anoxic process (AAA process) one aerobic-anoxic process (OAA process) sequencing batch reactor (SBR) alkalinity |
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