Biological removal of phenol from saline wastewater using a moving bed biofilm reactor containing acclimated mixed consortia.

Seyyed Ali Akbar Nakhli,Mohammad Hossein Rostami,Kimia Ahmadizadeh,Mahmood Fereshtehnejad,Seyyed Mehdi Borghei,Mojtaba Safari

doi:10.1186/2193-1801-3-112

Abstract

In this study, the performance of an aerobic moving bed biofilm reactor (MBBR) was assessed for the removal of phenol as the sole substrate from saline wastewater. The effect of several parameters namely inlet phenol concentration (200–1200 mg/L), hydraulic retention time (8–24 h), inlet salt content (10–70 g/L), phenol shock loading, hydraulic shock loading and salt shock loading on the performance of the 10 L MBBR inoculated with a mixed culture of active biomass gradually acclimated to phenol and salt were evaluated in terms of phenol and chemical oxygen demand (COD) removal efficiencies. The results indicated that phenol and COD removal efficiencies are affected by HRT, phenol and salt concentration in the bioreactor saline feed. The MBBR could remove up to 99% of phenol and COD from the feed saline wastewater at inlet phenol concentrations up to 800 mg/L, HRT of 18 h and inlet salt contents up to 40 g/L. The reactor could also resist strong shock loads. Furthermore, measuring biological quantitative parameters indicated that the biofilm plays a main role in phenol removal. Overall, the results of this investigation revealed that the developed MBBR system with high concentration of the active mixed biomass can play a prominent role in order to treat saline wastewaters containing phenol in industrial applications as a very efficient and flexible technology.

Highlights

Several industries including olive oil mills, pickled vegetables, fish processing, meat canning, dairy products, tanning process and oil refining process generate wastewaters containing high salt content and high organic concentration (Lefebvre and Moletta 2006)
This denotes that the part of phenol metabolized as a carbon and energy source has been completely biodegraded, further increasing inlet concentration showed an adverse effect on the removal efficiency
It can be concluded from above that an optimum hydraulic retention time (HRT) for the moving bed biofilm reactor (MBBR) under the selected operational conditions was 18 h, at which phenol and chemical oxygen demand (COD) removal efficiencies were above 99% and no metabolites were detected

Summary

Introduction

Several industries including olive oil mills, pickled vegetables, fish processing, meat canning, dairy products, tanning process and oil refining process generate wastewaters containing high salt content and high organic concentration (Lefebvre and Moletta 2006). Moving bed biofilm reactor (MBBR) is a highly effective biological treatment process that was introduced about 30 years ago and it is used in largescale all over the world (Rusten et al 2006). MBBR is a completely mixed and continuously operated biofilm reactor that is designed to offer the positive aspects of biofilm process including a stable removal efficiency of toxic pollutants, compact and simplicity of operation; without its drawbacks including high head loss, medium channeling and clogging (Chen et al 2008; Delnavaz et al 2010). As a consequence of such advantages MBBR process has been recently used for the removal of many toxic wastewaters including landfill leachate (Chen et al.2008), aniline (Delnavaz et al 2010), ammonium from saline wastewater (Bassin et al 2011), coal gasification wastewater (Li et al 2011), thiocyanate (Jeong and Chung 2006) and antibiotic fermentation-based pharmaceutical wastewater (Xing et al 2013)

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Conclusion