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Chen, Y., Zhu, J. Y., Qin, Y., Zhang, Z. M., & Yuan, S. C. (March-April, 2017). Reactivation of hypersaline aerobic granular sludge after low-temperature storage. Water Technology and Sciences (in Spanish), 8 (2), 61-70. Reactivation of hypersaline aerobic granular sludge after low-temperature storage was studied by slowly increasing the organic loading. Results indicated that the basic external features of thawed hypersaline aerobic granules were still largely intact after a six-week low temperature storage, but the colors and internal structure changed greatly. Aerobic granules experienced a process of particle disintegration, fragmentary particles, filamentous bacteria-like particles, and dense granules during the recovery process. After more than one-month re-cultivation, the settling property, dehydrogenase activity, and nitrification properties of hypersaline aerobic granules returned to normal. During the re-cultivated process, the decentralized growth pattern of particles can be effectively controlled, and granules can grow compactly by controlling water alkalinity, aeration rate and reactor settling time.

Qin, Y., Guo, J., & Fang, F. (March-April, 2017). Comparison on nitrosation and anaerobic ammonium oxidation between activated sludge and biofilm from an autotrophic nitrogen removal SBBR. Water Technology and Sciences (in Spanish), 8(2), 141-149. Activated sludge and biofilm from a Sequencing Biofilm Batch Reactor (SBBR) were studied to analyze their different roles in autotrophic nitrogen removal process. Results showed that under aerobic conditions, the ammonia oxidation rate of activated sludge was 100% and the maximum rate was 0.23 mgN mgVSS−1 d−1 during a 48 h test cycle. Under the same conditions, the ammonia oxidation rate of the biofilm was 72% and the maximum rate was 0.08 mgN mgVSS−1 d−1. The population of AOB (ammonium oxidizing bacteria) in activated sludge was 1.88×1011 cells/g, 10 times that in biofilm. The TN (total nitrogen) removal rate of activated sludge and biofilm under anaerobic conditions were 37% and 83%, respectively. The rate of anaerobic ammonium oxidation by activated sludge was 0.09 mgN mgVSS−1 d−1 and that of biofilm was 0.22 mgN mgVSS−1 d−1. ANAMMOX (anaerobic ammonium oxidizing bacteria) were the dominant bacteria in terms of cell number in this system, with 2.66×1012 cells/g in biofilm—2.6 times more than in activated sludge. TN was removed mainly by anaerobic ammonium oxidation.