Aerobic granulation for methylene blue biodegradation in a sequencing batch reactor Deng-Yue Ma a , Xin-Hua Wang a, ⁎, Chao Song a , Shu-Guang Wang a, ⁎, Mao-Hong Fan b , Xiao-Ming Li a a Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, China b Department of Chemical and Petroleum Engineering, 1000 E. University Ave., Laramie, WY 82071, USA abstract article info Article history: Received 1 December 2010 Received in revised form 24 February 2011 Accepted 18 March 2011 Available online 8 April 2011 Keywords: Aerobic granulation Methylene blue (MB) Biodegradation Sequencing batch reactor (SBR) Haldane model Aerobic granules to treat wastewater containing methylene blue (MB) were successfully developed in a sequencing batch reactor (SBR) using activated sludge as inoculum. After cultivation for 87 days, stable aerobic granules were obtained with a clearly defined shape and a diameters ranging from 2 to 4 mm. After granulation, the removal efficiencies of MB and chemical oxygen demand (COD) reached 56% and 93%, respectively. Specific MB biodegradation rates followed the Haldane model and the associated kinetic parameters were as follows: V max = 184.15 mg L -1 h -1 , K s = 209.96 mg L -1 , and K i = 21.23 mg L -1 . The aerobic granules proved to be a feasible and effective way to degrade MB-containing wastewater. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved. 1. Introduction Methylene blue (MB), a basic and cationic dye, has been widely used as a colorant, an indicator, and an antiseptic agent in clinical therapy [1,2]. However, disposal of MB-containing waters can cause severe damage to the environment. They not only do serious harm to aquatic species by affecting photosynthetic activity, but also cause cancer and mutation in humans [3–5]. Many human diseases have been reported to be closely related to MB, such as hemolytic anemia, hyperbilirubinemia, and acute renal failure [6]. It has been reported that even micromolar levels of MB can induce cytotoxicity in SK-N-MC human neuroblastoma and U-373 MG human astrocytoma cells [7]. Hence, the removal of MB is a very important task in the protection of our environment and health. To date, the most widely used methods for the removal of MB from dye-rich wastewater are physicochemical ones, such as photocatalytic degradation [8,9], sonochemical degradation [10], ultrafiltration [11] and physical adsorption on activated carbon [12,13] or pyrolyzed petrified sediment [14]. These methods are attractive for their high efficiency, but are complicated and expensive [15]. Biochemical methods including biosorption with algae [16], plant powders [17,18] and baker's yeast [19] are alternative ways to treat MB-containing wastewater. But, like the physicochemical methods, the aforementioned biological methods leave a large quantity of waste biosorbents that need to be treated after sorption. Traditional wastewater treatment technologies have proven to be rather ineffective in handling waste- water containing synthetic textile dyes due to the chemical stability of such contaminants [20]. Aerobic (anaerobic) granulation technology is an alternative method [21,22]. Anaerobic granules are well known for their ability to remove MB when a suitable amount of sucrose and peptone is added [23]. But little is known about the effect of aerobic granulation technology for MB biodegradation. Aerobic granules have many advantages over conventional activated sludge, such as strong structure, excellent settling ability, high biomass retention, and resistance to inhibitory and toxic compounds [24–28]. Furthermore, aerobic granules can be cultivated in sequencing batch reactors (SBRs) and simply developed without any extra carrier material. Therefore, the aim of this study was to explore the feasibility of cultivating aerobic granules for MB biodegradation, and the degradation kinetics and the effects of anaerobic phase and biosorption were also investigated. 2. Materials and methods 2.1. Methylene blue The tested chemical MB, a synthetic thiazine (Tianjin Kermel Chemical Reagent Co., Ltd), was of analytical grade. The absorbance was measured with a UV–vis spectrophotometer (model UV754GD, Shanghai) at its maximum absorption wavelength of 665 nm. The chemical formula of methylene blue is shown in Fig. 1 [29]. 2.2. Reactor operation The 4-L column-type sequencing batch reactor (SBR, 100 cm in height and 8 cm in diameter) used in the study was housed in a temperature-controlled room at 25 ± 2 °C and operated sequentially in Desalination 276 (2011) 233–238 ⁎ Corresponding authors. Tel.: + 86 531 88362802; fax: + 86 531 88364513. E-mail addresses: xinhuawang@sdu.edu.cn (X.-H. Wang), wsg@sdu.edu.cn (S.-G. Wang). 0011-9164/$ – see front matter. Crown Copyright © 2011 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.desal.2011.03.055 Contents lists available at ScienceDirect Desalination journal homepage: www.elsevier.com/locate/desal