Elsevier

Bioresource Technology

Volume 203, March 2016, Pages 370-373
Bioresource Technology

Short Communication
Effective biodegradation of nitrate, Cr(VI) and p-fluoronitrobenzene by a novel three dimensional bioelectrochemical system

https://doi.org/10.1016/j.biortech.2015.12.059Get rights and content

Highlights

  • The BES showed satisfied single NO3single bondN, Cr(VI), and p-FNB removal abilities.

  • NO3single bondN and Cr(VI) could be reduced by degrading p-FNB.

  • This investigation achieved the aim of using waste to treat waste.

Abstract

p-Fluoronitrobenzene (p-FNB) was degraded in a novel three dimensional bioelectrochemical system (3D BES) and potentially utilized as carbon source for achieving both nitrate (NO3single bondN) and Cr(VI) reduction. For single NO3single bondN and Cr(VI) removal, 200 mg L−1 NO3single bondN and 100 mg L−1 Cr(VI) could be almost completely converted to N2 and Cr(III) at current 50 mA. For single p-FNB degradation, 100 mg L−1 p-FNB was completely degraded at current 50 mA. The critical current for defluorination was 40 mA, and the intermediate product p-fluoroaniline (p-FA) tended to decrease when current was higher than 40 mA. When NO3single bondN, Cr(VI), and p-FNB were both coexisted in this system, the average NO3single bondN, Cr(VI), and p-FNB removal efficiencies slightly decreased with addition of carbon source. Without carbon source, NO3single bondN and Cr(VI) removal rates reached 34.45% and 41.38% with 91.02% p-FNB degradation, proving that NO3single bondN and Cr(VI) could be reduced by degrading p-FNB in the BES.

Introduction

It is urgent to remove nitrate in natural waters because nitrate pollution becomes more and more serious with increasing industrialization, and thus causing deleterious effect on human and environment (Bi et al., 2015, Fowdar et al., 2015, Ghafari et al., 2008). Since many kinds of industrial waters such as pigmenting, textile dyeing, electroplating, agrochemicals, pharmaceuticals, and aerosol propellants (Murphy et al., 2008, Zayed and Terry, 2003) always discharge into natural waters without effective treatment, Cr(VI) and p-fluoronitrobenzene contaminations in natural waters become an imperative problem needing effective and economical approach to renovate. Although there are numerous efficient methods such as reverse osmosis, ion exchange, and aerobic biodegradation for single nitrate, Cr(VI) and p-fluoronitrobenzene removal (Karanasios et al., 2010, Lameiras et al., 2008, Xie et al., 2014), seeking for a better scheme to achieve both nitrate, Cr(VI) and p-fluoronitrobenzene degradation in one system will be a challenging problem.

In recent years, bioelectrochemical method has gained much attention because this technology has the advantages of effective pollutant removal, easy control and operation, and environmental compatibility (Nancharaiah et al., 2015). Some researchers used the bioelectrochemical method for nitrate removal (Xie et al., 2014), heavy metal degradation (Wang and Ren, 2014), organic matter and salt ions removal (Kim and Logan, 2013) and confirmed that bioelectrochemical system had a very good prospect for wastewater remediation.

In this work, a novel 3D bioelectrochemical system was developed to treat NO3single bondN, Cr(VI), and p-FNB coexisting wastewater. This BES overcame the disadvantage of conventional system due to that sulfur autotrophic process always generated H+, which could be used for hydrogen autotrophic phase, leading to balanced pH environment. On the other hand, sulfur part shared the pollutant load, and thus increasing the overall removal rate. An attempt was made to confirm if this system could reduce NO3single bondN and Cr(VI) by degrading p-FNB. The exploration in this work would provide new thoughts for complex industrial wastewater treatment.

Section snippets

Reactor operation

A cylindrical reactor was used in this study (Fig. 1). The valid volume was 3000 mL. A piece of graphite felt was used as cathode and placed closed to the interior wall of the reactor. A carbon rod (diameter 8 mm) was used as anode and placed in the middle of the reactor. The whole reactor was filled with sulfur granules (diameter 5.0–8.0 mm). Cathode and anode were connected to a direct current power source (RPS-3005D, 0–30 V, 0–5 A). Two duplicate reactors were used as controls: a single 3D

NO3single bondN removal

As shown in Fig. 2a, the NO3single bondN, Cr(VI), p-FNB removal rates by ES control and BS control were very low and thus could be neglected. Fig. 2b shows that NO3single bondN removal rate increased from 64.02% to 97.45% with current increased from 10 to 60 mA, due to the reason that higher current accelerated the electron transport in this system. The intermediate product NO2single bondN was slightly accumulated when current varied from 10 to 40 mA. The maximum SO42− concentration was 86.10 mg L−1, which was lower than 250 mg L

Conclusions

The novel BES was proved to perform satisfied degradation abilities of single pollutant NO3single bondN, Cr(VI), and p-FNB. Based on the investigation in the three pollutant coexisting system, it could be concluded that both NO3single bondN and Cr(VI) could be reduced by degrading p-FNB in the BES. This scheme not only decreased the operation cost, but also achieved the aim of using waste to treat waste. Thus, this approach was a promising solution for renovating wastewater containing complex pollutants.

Acknowledgements

This work was financially supported by the National Natural Science Foundation of China (NSFC) (51378400) and the National Science and Technology Pillar Program (2014BAL04B04).

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