Dynamics of microbial community for X-3B wastewater decolorization coping with high-salt and metal ions conditions Liang Tan a , Yuanyuan Qu a , Jiti Zhou a , Fang Ma b, * , Ang Li a a Key Laboratory of Industrial Ecology and Environmental Engineering, MOE, School of Environmental and Biological Science and Technology, Dalian University of Technology, Dalian 116024, PR China b State Key Lab of Urban Water Resource and Environment, School of Municipal and Environmental Engineering, Harbin Institute of Technology, Harbin 150090, PR China article info Article history: Received 19 November 2008 Received in revised form 4 January 2009 Accepted 11 January 2009 Available online 20 February 2009 Keywords: Decolorization Azo dye Salinity Metal ions Microbial community abstract In this study, decolorization of Reactive Brilliant Red X-3B wastewater by the biological process coping with high salinity and metal ions conditions was investigated, and 16S rDNA based fingerprint technique was used to investigate microbial population dynamics. Results of sequencing batch tests showed that the microbial community could keep efficient with high concentration of dye (1100 mg L 1 ), salt (150 g L 1 NaCl) and some metal ions such as Mg 2+ , Ca 2+ (1–10 mmol L 1 ) and Pb 2+ (1 mmol L 1 ). 16S rDNA-based molecular analysis techniques demonstrated that the microbial community shifted during the acclimatization process affected by salt or metal ions. Some stains similar to Bacillus, Sedimentibacter, Pseudomonas, Clostridiales, Streptomyces and some uncultured clones acted for the dynamic succession, supposed as potential decolorization bacteria. This study provided insights on the decolorization capabil- ity and the population dynamic shifts during decolorization process of azo dye wastewater coping with salt and metal ions. Ó 2009 Elsevier Ltd. All rights reserved. 1. Introduction Azo dyes, with one or more ‘‘–N@N–” groups, represent the largest class of dyes applied in textile industry. In textile dye baths, fixation of dyes to fabrics is always incomplete, which causes a great mount of dye containing effluents discharged to environment every year worldwide (O’Neill et al., 1999b). Some azo dyes and their metabolic intermediates (e.g. aromatic amines) are toxic and potentially mutagenic and carcinogenic. However, the removal of these compounds has posed a large challenge by its inherent vir- tues such as high water solubility and low exhaustion (Spadaro et al., 1992). Nowadays, it has been emphasized as an important is- sue on available treatment of azo dye wastewater (Anjali et al., 2007). Wastewater from dyeing and printing industry always contains unused dyes, sizing agents and dyeing aids. Generally, unused dyes are mainly composed of organic component, which require for effi- cient and direct removal from wastewater. In recent years, many physicochemical methods have been adopted to eliminate organic component (namely decolorization) from dyes containing effluents (Aziz et al., 2007; Sessa and Palmquist, 2008). However, biological process, as an economic, efficient and environmental-friendly alternative has been drawing an increasing interest for recent dec- ades. Many microorganisms, including fungi, bacteria, yeast and al- gae have been reported to have the potential to decolorize or mineralize azo dyes (Kolekar et al., 2008; Ambrósio and Campos-Takaki, 2004; Omar, 2008). In the field application, pure cultures cannot adapt the complex conditions and maintain long period operation (Coughlin et al., 1997). Acclimated microbial community is a more appropriate and efficient approach for decolorization of azo dyes. Extensive studies have been carried out on reliable biological community processes in azo dyes decolorization recently. An immobilized microbial consortium was acclimatized for rapidly decolorizing 1000 mg L 1 azo dye Direct Fast Scarlet 4BS completely, and the apparent maximum specific decolorization rate was 81.25 mg L 1 h 1 (He et al., 2004). An acclimatized activated sludge from a textile effluent treatment plant showed 70–90% decolorization efficiency in treating 1000 mg L 1 C. I. Reactive Black 5 solution within 48 h (Dafale et al., 2008). Besides organic pollutants, high concentration of salts (up to 150–200 g L 1 ) was consequence product of batch processes in both the dye manufacturing and consuming industries (EPA, 1997; Manu and Chauhari, 2003). Hyper-salinity wastewater usu- ally caused plasmolysis and/or loss of activity of cells and brought negative impacts to the aerobic or anaerobic biological treatments process (Peyton et al., 2002). Thereafter, the effect of salinity on decolorization process needed to be evaluated. Previously reported studies indicated that some special microorganisms could keep high efficiency even under high-salt conditions since they had a prominent capacity to produce and accumulate some substance 0960-8524/$ - see front matter Ó 2009 Elsevier Ltd. All rights reserved. doi:10.1016/j.biortech.2009.01.010 * Corresponding author. Tel.: +86 451 86282107; fax: +86 411 84706252. E-mail address: hit_dlut@yahoo.cn (F. Ma). Bioresource Technology 100 (2009) 3003–3009 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech