Hindawi Publishing Corporation BioMed Research International Volume 2013, Article ID 396487, 9 pages http://dx.doi.org/10.1155/2013/396487 Research Article Start-Up Characteristics of a Granule-Based Anammox UASB Reactor Seeded with Anaerobic Granular Sludge Lei Xiong, 1,2 Yun-Yan Wang, 1,2 Chong-Jian Tang, 1,2 Li-Yuan Chai, 1,2 Kang-Que Xu, 1,2 Yu-Xia Song, 1,2 Mohammad Ali, 1,2 and Ping Zheng 3 1 School of Metallurgy and Environment, Central South University, Changsha 410083, China 2 National Engineering Research Center for Control and Treatment of Heavy Metal Pollution, Changsha 410083, China 3 Department of Environmental Engineering, Zhejiang University, Zijingang Campus, Hangzhou 310058, China Correspondence should be addressed to Chong-Jian Tang; chjtang@csu.edu.cn Received 20 September 2013; Accepted 22 November 2013 Academic Editor: Qaisar Mahmood Copyright © 2013 Lei Xiong et al. his is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. he granulation of anammox sludge plays an important role in the high nitrogen removal performance of the anammox reactor. In this study, anaerobic granular sludge was selected as the seeding sludge to start up anammox reactor in order to directly obtain anammox granules. Results showed that the anammox UASB reactor was successfully started up by inoculating anaerobic granular sludge, with substrate capacity of 4435.2 mg/(L⋅d) and average ammonium and nitrite removal eiciency of 90.36% and 93.29%, respectively. During the start-up course, the granular sludge initially disintegrated and then reaggregated and turned red, suggesting the high anammox performance. Zn-Fe precipitation was observed on the surface of granules during the operation by SEM-EDS, which would impose inhibition to the anammox activity of the granules. Accordingly, it is suggested to relatively reduce the trace metals concentrations, of Fe and Zn in the conventional medium. he indings of this study are expected to be used for a shorter start-up and more stable operation of anammox system. 1. Introduction Anaerobic ammonia oxidation (anammox) is one of the latest additions to the biogeochemical nitrogen cycle initially dis- covered in the 1990s [1]. It involves the autotrophic oxidation of ammonium to dinitrogen gas using nitrite as electron acceptor under anaerobic conditions (1)[1, 2]. he process is performed by microorganisms belonging to the order Brocadiales and ailiated to the Planctomycetes: NH 4 + + 1.32NO 2 − + 0.066HCO 3 − + 0.13H + → 1.0N 2 + 0.26NO 3 − + 0.066CH 2 O 0.5 N 0.15 + 2.03H 2 O (1) In contrast to conventional biological nitrogen removal processes, anammox presents advantages in less operational costs and higher nitrogen removal eiciency due to its low dependency of oxygen, none organic carbon consumption, and less sludge production [2, 3]. hus, anammox has at- tracted much attention in the ields of environmental science and engineering. Several full-scale anammox plants have been employed for nitrogen removal from ammonium-rich wastewaters with maximum nitrogen removal rate (NRR) up to 9500 mg/(L ⋅ d) [3, 4]. However, the anammox microbes are characterized by a very slow growth rate with their doubling time best estimated at 7–11 d [5]. he enrichment of anammox bacteria from a mixed inoculum requires the optimization of conditions favorable for the anammox bacteria and generally takes 200– 300 days [3, 6, 7]. he long start-up has been becoming one choke point on the application of the anammox process. Study of anammox start-up has been focused on factors that have been found to have an impact on cultivation of anammox bacteria including hydraulic retention time (HRT), dissolved oxygen (DO), inoculum, temperature, wastewater composition, nitrogen compound concentration, and reactor