Search

BACKGROUND Traditional aerobic autotrophic nitrification and anoxic heterotrophic denitrification have many limitations. Recently, the simultaneous heterotrophic nitrification-aerobic denitrification (HN-AD) process has received increasing attention. Thus, the possibility of the simultaneous removal of bisphenols and NH4+-N via HN-AD was investigated. RESULTS A bisphenols-degrading bacterial consortium was enriched and capable of degrading 50 mg L−1 bisphenol A, 300 mg L−1 4,4-dihydroxybenzophenone, 375 mg L−1 bisphenol F (BPF) and 10 mg L−1 bis(4-hydroxyphenyl)sulfide under aerobic conditions. Further studies showed that the bacterial consortium could completely degrade 300 mg L−1 BPF and remove NH4+-N at 35 °C with 150 rpm at the C/N ratio of over 10. Moreover, BPF mineralization and NH4+-N reduction to N2 were observed. Clone library analysis indicated that Salmonella enterica, Enterobacter, Citrobacter and Pseudomonas could cooperate to degrade BPF and reduce NH4+-N to N2. Among these species, the isolated Pseudomonas sp. HS-2 was capable of simultaneous BPF degradation and NH4+-N removal via HN-AD. CONCLUSION The experimental results demonstrated that the enriched bacterial consortium and the isolated strain HS-2 could simultaneously remove BPF and NH4+-N via HN-AD, indicating that this is a potential way for the treatment of wastewaters containing these compounds. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND The co-existence of NH3-N and Cr(VI) in natural water is a common and growing problem. The electron competition ability of Cr(VI) with NO3-N/NO2-N enabled the reduction of Cr(VI) complex during the process of simultaneous nitrification/denitrification (SND). The current study focused on exploring the interaction between Cr(VI) reduction and SND by Acinetobacter sp. WB-1. RESULTS Different Cr(VI) concentrations had no effect on NH3-N removal, while increased Cr(VI) concentration (1-30 mg L−1) could affect the rates of reduction of NO3-N/NO2-N. However, NH3-N at concentrations ranging from 100 to 400 mg L−1 had no influence on Cr(VI) reduction. The location/contribution of cellular components demonstrated cytoplasm and filtered spent medium had the ability to reduce Cr(VI) to Cr(III). Cell debris could not reduce Cr(VI) but could accumulate Cr(III). CONCLUSION The denitrification process was more sensitive to the presence of Cr(VI) than the nitrification process. The inhibition of NO3-N reduction was due to the toxicity and electron competition ability of Cr(VI). The inhibitory effect on NO2-N reduction was mainly dependent on the toxicity of Cr(VI) to NO2-N reductase. Cr(VI) removal by strain WB-1 was suggested to be realized through surface immobilization along with intracellular and extracellular reduction. © 2016 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND Traditional anaerobic bioprocesses have failed to achieve the efficient biotransformation of nitrobenzene. Thus, graphene-anaerobic sludge composite as a novel biocatalyst was proposed for the enhancement of nitrobenzene biotransformation. RESULTS Reduced graphene oxide/anaerobic sludge ( RGO/ AS) composite presented good settling performance when graphene oxide ( GO) was added into an AS system for 24 h cultivation. The presence of RGO resulted in enhanced nitrobenzene biotransformation by AS, and the highest removal efficiency of nitrobenzene was observed with initial GO (3-5 µm) vs sludge ratio of 0.075 (w/w). Dehydrogenase activity in the RGO/ AS system increased approximately 2-fold over that in the AS system and redox active species appeared in supernatant from the RGO/ AS system. The ratio of acetate to propionate increased in the RGO/ AS system during glucose fermentation, and nitrobenzene biotransformation by both AS and RGO/ AS systems was independent of methanogenesis, but dependent on acetogenesis. Moreover, bound and free extracellular polymeric substances ( EPS) from RGO/ AS composite were involved in direct biotransformation of nitrobenzene, and bound EPS might interact with secreted redox active species to accelerate nitrobenzene biotransformation by extracellular electron transfer. CONCLUSION RGO/ AS composite was efficient for the treatment of nitrobenzene wastewater. © 2013 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

BACKGROUND: Traditional treatment systems failed to achieve efficient degradation of anthraquinone dye intermediates at high loading. Thus, an airlift internal loop reactor ( AILR) in combination with the TiO2-photocatalytic ozonation ( TiO2/ UV/ O3) process was investigated for the degradaton of 1-amino- 4-bromoanthraquinone-2- sulfonic acid ( ABAS). RESULTS: The AILR using Sphingomonas xenophaga as inoculum and granular activated carbon ( GAC) as biocarrier, could run steadily for 4 months at 1000 mg L−1 of the influent ABAS. The efficiencies of ABAS decolorization and chemical oxygen demand ( COD) removal in AILR reached about 90% and 50% in 12 h, respectively. However, when the influent ABAS concentration was further increased, a yellow intermediate with maximum absorbance at 447 nm appeared in AILR, resulting in the decrease of the decolorization and COD removal efficiencies. Advanced treatment of AILR effluent indicated that TiO2/ UV/ O3 process more significantly improved the mineralization rate of ABAS bio-decolorization products with over 90% TOC removal efficiency, compared with O3, TiO2/ UV and UV/ O3 processes. Furthermore, the release efficiencies of Br− and SO42− could reach 84.5% and 80.2% during TiO2/ UV/ O3 treatment, respectively, when 91.5% TOC removal was achieved in 2 h. CONCLUSION: The combination of AILR and TiO2/ UV/ O3 was an economic and efficient system for the treatment of ABAS wastewater. © 2012 Society of Chemical Industry [ABSTRACT FROM AUTHOR]