Fabrication of novel oxygen-releasing alginate beads as an efficient oxygen carrier for the enhancement of aerobic bioremediation of 1,4-dioxane contaminated groundwater Chung-Seop Lee a , Thao Le Thanh a , Eun-Ju Kim a , Jianyu Gong a , Yoon-Young Chang b , Yoon-Seok Chang a,⇑ a School of Environmental Science and Engineering, Pohang University of Science and Technology (POSTECH), Pohang 790-784, Republic of Korea b Department of Environmental Engineering, Kwangwoon University, Seoul 139-701, Republic of Korea highlights  Novel oxygen-releasing alginate beads (ORABs) were newly fabricated.  The oxygen-releasing properties of ORABs were tested in real groundwater conditions.  The size and valence of cross-linking ions greatly affected the properties of ORABs.  A synergistic effect on 1,4-dioxane biodegradation was observed only with ORABs. graphical abstract article info Article history: Received 17 June 2014 Received in revised form 6 August 2014 Accepted 7 August 2014 Available online 15 August 2014 Keywords: Alginate bead Oxygen release Bioremediation 1,4-Dioxane Mycobacterium sp. PH-06 abstract Oxygen-releasing alginate beads (ORABs), a new concept of oxygen-releasing compounds (ORCs) designed to overcome some limitations regarding the fast oxygen release rate and the high pH equilib- rium of ORCs, were fabricated to promote the stimulation of aerobic biodegradation in anaerobic ground- water. Slow oxygen-releasing rate and maintenance of constant pH were achieved by changing the parameters (ionic radius and valence) related to the cross-linking ions composing ORABs, and the best results were obtained for ORABs cross-linked with Al (Al-ORABs). Furthermore, the mechanism of the improved aerobic biodegradation using Al-ORABs under oxygen-limiting groundwater conditions was elucidated in batch and column studies with 1,4-dioxane and Mycrobacterium sp. PH-06 as a model con- taminant and aerobic microbes, respectively. Maximum 1,4-dioxane degradations of 99% and 68.1% were achieved when Al-ORABs were applied in batch and column conditions, respectively, whereas 34.3% and 18% of 1,4-dioxane were degraded without Al-ORABs in batch and column conditions, respectively. Ó 2014 Elsevier Ltd. All rights reserved. 1. Introduction Contamination of groundwater due to hazardous and toxic pol- lutants is one of the major problems throughout the industrialized world today. Various conventional remediation technologies (e.g., pump and treat, air sparging, bioremediation, chemical oxidation and phytoremediation) have been used to remediate contaminated groundwater (Mackay and Cherry, 1989; Brunsting and McBean, 2014; Li et al., 2010; Liang et al., 2011; Vangronsveld et al., 2009). Among these technologies, bioremediation has emerged as an inexpensive and environmentally friendly remediation strategy (Li et al., 2010). However, the low concentration of dissolved oxy- gen (DO) in groundwater (below 3 mg/L) could significantly reduce the efficiency of intrinsic bioremediation. Moreover, the negative impacts of severe DO deficiency that frequently arise from http://dx.doi.org/10.1016/j.biortech.2014.08.039 0960-8524/Ó 2014 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. Tel.: +82 54 279 2281; fax: +82 54 279 8299. E-mail address: yschang@postech.ac.kr (Y.-S. Chang). Bioresource Technology 171 (2014) 59–65 Contents lists available at ScienceDirect Bioresource Technology journal homepage: www.elsevier.com/locate/biortech