Evaluation of Anaerobic/Anoxic/Oxic (A(2)/O) and Reverse A(2)/O Processes in Biological Nutrient Removal

作者：Xu Shengnan; Bernards Matthew; Hu Zhiqiang^*

来源：Water Environment Research, 2014, 86(11): 2186-2193.

DOI：10.2175/106143014X14062131178394

• biological nutrient removal
• nitrifying bacteria
• phosphate accumulating organisms
• A(2)/O and reverse A(2)/O
• oxidation-reduction potential

A performance comparison between the conventional anaerobic/anoxic/oxic (A(2)/O) process and the anoxic/anaerobic/oxic (reverse A(2)/O) process was conducted in lab-scale at the hydraulic retention time of 0.75 d and solids retention time of 10 d for more than 200 days. Both processes demonstrated excellent removal efficiency for organic matter (> 96%) and total nitrogen (> 85%), with no significant difference in microbial activities, sludge phosphorus (P) content, sludge settling property, and nitrifying community (dominated by Nitrosomonas and Nitrospira). However, there was significant difference in P removal, with the total P removal efficiencies in the reverse A(2)/O and A(2)/O systems of 76 +/- 6% and 70 +/- 6%, respectively. Placing an anoxic stage before the anaerobic stage in the reverse A(2)/O process resulted in a lower oxidation-reduction potential (ORP = 268 +/- 45 mV) of the anaerobic zone, which contributed to higher P uptake by bacteria under subsequent aerobic respiration.

• 出版日期2014-11