Zero valent iron simultaneously enhances methane production and sulfate reduction in anaerobic granular sludge reactors.

Zero valent iron (ZVI) packed anaerobic granular sludge reactors have been developed for improved anaerobic wastewater treatment. In this work, a mathematical model is developed to describe the enhanced methane production and sulfate reduction in anaerobic granular sludge reactors with the addition of ZVI. The model is successfully calibrated and validated using long-term experimental data sets from two independent ZVI-enhanced anaerobic granular sludge reactors with different operational conditions. The model satisfactorily describes the chemical oxygen demand (COD) removal, sulfate reduction and methane production data from both systems. Results show ZVI directly promotes propionate degradation and methanogenesis to enhance methane production. Simultaneously, ZVI alleviates the inhibition of un-dissociated H2S on acetogens, methanogens and sulfate reducing bacteria (SRB) through buffering pH (Fe(0) + 2H(+) = Fe(2+) + H2) and iron sulfide precipitation, which improve the sulfate reduction capacity, especially under deterioration conditions. In addition, the enhancement of ZVI on methane production and sulfate reduction occurs mainly at relatively low COD/ [Formula: see text] ratio (e.g., 2-4.5) rather than high COD/ [Formula: see text] ratio (e.g., 16.7) compared to the reactor without ZVI addition. The model proposed in this work is expected to provide support for further development of a more efficient ZVI-based anaerobic granular system.

[1]  Thorkild Hvitved-Jacobsen,et al.  Sulfide-iron interactions in domestic wastewater from a gravity sewer. , 2005, Water research.

[2]  Amarjeet Bassi,et al.  Long-term performance of high-rate anaerobic reactors for the treatment of oily wastewater. , 2006, Environmental science & technology.

[3]  Xiao Xiao,et al.  A modeling approach to describe ZVI-based anaerobic system. , 2013, Water research.

[4]  Feng Ying,et al.  Bioaugmented sulfate reduction using enriched anaerobic microflora in the presence of zero valent iron. , 2008, Chemosphere.

[5]  R. Sierra-Alvarez,et al.  Removal of copper in an integrated sulfate reducing bioreactor-crystallization reactor system. , 2007, Environmental science & technology.

[6]  James M. Tiedje,et al.  Competition between sulfate-reducing and methanogenic bacteria for H2 under resting and growing conditions , 2004, Archives of Microbiology.

[7]  C. O'Reilly,et al.  Effect of influent COD/SO4(2-) ratios on mesophilic anaerobic reactor biomass populations: physico-chemical and microbiological properties. , 2006, FEMS microbiology ecology.

[8]  Luming Ma,et al.  Enhanced biological treatment of industrial wastewater with bimetallic zero-valent iron. , 2008, Environmental science & technology.

[9]  Reyes Sierra-Alvarez,et al.  Zero valent iron as an electron-donor for methanogenesis and sulfate reduction in anaerobic sludge. , 2005, Biotechnology and bioengineering.

[10]  Yi Jing Chan,et al.  A review on anaerobic-aerobic treatment of industrial and municipal wastewater. , 2009 .

[11]  Xie Quan,et al.  Steady performance of a zero valent iron packed anaerobic reactor for azo dye wastewater treatment under variable influent quality. , 2012, Journal of environmental sciences.

[12]  Motoyuki Yoda,et al.  Long term competition between sulfate-reducing and methane-producing bacteria for acetate in anaerobic biofilm , 1987 .

[13]  Huimin Zhao,et al.  Effects of an electric field and zero valent iron on anaerobic treatment of azo dye wastewater and microbial community structures. , 2011, Bioresource technology.

[14]  D. Massé,et al.  Comprehensive model of anaerobic digestion of swine manure slurry in a sequencing batch reactor , 2000 .

[15]  Xie Quan,et al.  Adding Fe0 powder to enhance the anaerobic conversion of propionate to acetate , 2013 .

[16]  Hanqing Yu,et al.  Coupling glucose fermentation and homoacetogenesis for elevated acetate production: Experimental and mathematical approaches , 2011, Biotechnology and bioengineering.

[17]  Hanqing Yu,et al.  Modeling a granule‐based anaerobic ammonium oxidizing (ANAMMOX) process , 2009, Biotechnology and bioengineering.

[18]  Shuo Chen,et al.  Optimization of anaerobic acidogenesis by adding Fe0 powder to enhance anaerobic wastewater treatment , 2012 .

[19]  Sergey Kalyuzhnyi,et al.  Extension of Enaerobic Digestion Model No. 1 with processes of sulfate reduction , 2003, Applied biochemistry and biotechnology.

[20]  E Morgenroth,et al.  Syntrophic acetate oxidation in two-phase (acid-methane) anaerobic digesters. , 2011, Water science and technology : a journal of the International Association on Water Pollution Research.

[21]  M. Alves,et al.  Modelling inhibitory effects of long chain fatty acids in the anaerobic digestion process. , 2013, Water research.

[22]  P. Lens,et al.  Anaerobic sludge granulation. , 2004, Water research.

[23]  J Keller,et al.  The influence of substrate kinetics on the microbial community structure in granular anaerobic biomass. , 2004, Water research.

[24]  S. Bhattacharya,et al.  Effects of Chlorophenols and Nitrophenols on the Kinetics of Propionate Degradation in Sulfate-Reducing Anaerobic Systems , 1997 .

[25]  H. Siegrist,et al.  The IWA Anaerobic Digestion Model No 1 (ADM1). , 2002, Water science and technology : a journal of the International Association on Water Pollution Research.

[26]  Mauro Majone,et al.  Magnetite particles triggering a faster and more robust syntrophic pathway of methanogenic propionate degradation. , 2014, Environmental science & technology.

[27]  R. Speece.  A survey of municipal anaerobic sludge digesters and diagnostic activity assays , 1988 .

[28]  Xie Quan,et al.  Enhanced anaerobic digestion of waste activated sludge digestion by the addition of zero valent iron. , 2014, Water research.

[29]  Joo-Hwa Tay,et al.  Mechanisms and models for anaerobic granulation in upflow anaerobic sludge blanket reactor. , 2003, Water research.

[30]  Shuo Chen,et al.  Enhanced azo dye wastewater treatment in a two-stage anaerobic system with Fe0 dosing. , 2012, Bioresource technology.

[31]  Xie Quan,et al.  A built-in zero valent iron anaerobic reactor to enhance treatment of azo dye wastewater. , 2011, Water science and technology : a journal of the International Association on Water Pollution Research.

[32]  W. Choi,et al.  Anaerobic treatment of palm oil mill effluent using combined high-rate anaerobic reactors. , 2013, Bioresource technology.

[33]  Huimin Zhao,et al.  Applying an electric field in a built-in zero valent iron--anaerobic reactor for enhancement of sludge granulation. , 2011, Water research.

[34]  Huimin Zhao,et al.  Bioaugmentation and functional partitioning in a zero valent iron-anaerobic reactor for sulfate-containing wastewater treatment , 2011 .

[35]  K. Hanaki,et al.  Protection of methanogenic bacteria from low pH and toxic materials by immobilization using polyvinyl alcohol , 1994 .

[36]  H. Chou,et al.  Competitive reaction kinetics of sulfate-reducing bacteria and methanogenic bacteria in anaerobic filters. , 2008, Bioresource technology.

[37]  V. O’Flaherty,et al.  Effect of sulphate addition on volatile fatty acid and ethanol degradation in an anaerobic hybrid reactor. II: microbial interactions and toxic effects , 1999 .

[38]  Han-Qing Yu,et al.  Hydrodynamics of upflow anaerobic sludge blanket reactors , 2009 .

[39]  L. T. Angenent,et al.  Characterization of microbial trophic structures of two anaerobic bioreactors processing sulfate-rich waste streams. , 2009, Water research.

[40]  A. Stams,et al.  Anaerobic transformation of beta-hexachlorocyclohexane by methanogenic granular sludge and soil microflora. , 1998 .

[41]  G Lettinga,et al.  Kinetics and mass-transfer phenomena in anaerobic granular sludge. , 2001, Biotechnology and bioengineering.

[42]  K. Hanaki,et al.  Selective use of microorganisms in anaerobic treatment processes by application of immobilization , 1994 .

[43]  R. Thauer,et al.  Kinetic mechanism for the ability of sulfate reducers to out-compete methanogens for acetate , 1982, Archives of Microbiology.

[44]  L. Bastiaens,et al.  Ten year performance evaluation of a field-scale zero-valent iron permeable reactive barrier installed to remediate trichloroethene contaminated groundwater. , 2010, Environmental science & technology.