title: Induction of anoxic microenvironment in multi-phase metabolic shift strategy during periodic discontinuous batch mode operation enhances treatment of azo dye wastewater.
abstract: Variation in anoxic microenvironment (multi-phase (MP) metabolic shift strategy) during cycle operation of periodic discontinuous batch/sequencing batch (PDBR/SBR) mode operation showed enhanced degradation of recalcitrant azo dye (C.I. Acid Black 10B) at higher dye load (1250mg/l). The process performance was evaluated by varying anoxic phasing period during cycle operation. Before multiphase (BMP) operation with 2.1% of anoxic period showed color/COD removal efficiency of 41.9%/46.3%. Increment in anoxic period responded favorable in enhancing treatment efficiency [AMPI (16.2%), 49.4%/52.4%; AMPII (26.6%), 54.7%/57.2%; AMPIII (34.9%), 58.4%/61.5%]. Relatively higher bio-electrochemical activity, persistent reductive behavior (redox catalytic currents, 0.26/-0.72μA), prevalence of redox shuttlers (Fe-S proteins, cytochromes, quinones) facilitating enhanced electron transfer by minimization of associated losses and higher enzyme activities were observed with induction of anoxic phase. Anoxic condition shifts system microenvironment between oxidation and reduction assisting reduction of dye to its intermediates followed by their mineralization.
authors.affiliation: Academy of Scientific and Innovative Research (AcSIR), Bioengineering and Environmental Centre (BEEC), CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, India.
authors.forename: C
authors.initials: C
authors.lastname: Nagendranatha Reddy
authors.affiliation: Academy of Scientific and Innovative Research (AcSIR), Bioengineering and Environmental Centre (BEEC), CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, India.
authors.forename: A
authors.initials: A
authors.lastname: Naresh Kumar
authors.affiliation: Academy of Scientific and Innovative Research (AcSIR), Bioengineering and Environmental Centre (BEEC), CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, India.
authors.forename: J
authors.initials: J
authors.lastname: Annie Modestra
authors.affiliation: Academy of Scientific and Innovative Research (AcSIR), Bioengineering and Environmental Centre (BEEC), CSIR-Indian Institute of Chemical Technology (CSIR-IICT), Hyderabad 500007, India. Electronic address: vmohan_s@yahoo.com.
authors.forename: S
authors.initials: S
authors.lastname: Venkata Mohan
mesh_terms: D000693:Anaerobiosis; D001391:Azo Compounds / Q000302:isolation & purification*; D001419:Bacteria / Q000201:enzymology / Q000378:metabolism*; D061249:Batch Cell Culture Techniques / Q000379:methods*; D001673:Biodegradation, Environmental; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology; D004396:Coloring Agents / Q000302:isolation & purification*; D055664:Electrochemical Techniques; D005232:Fatty Acids, Volatile / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D009601:Nitroreductases; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000378:metabolism; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000302:isolation & purification*; D018508:Water Purification / Q000379:methods*
chemical_list: D001391:Azo Compounds; D004396:Coloring Agents; D005232:Fatty Acids, Volatile; D009247:NADH, NADPH Oxidoreductases; D009601:Nitroreductases; D010088:Oxidoreductases; D062065:Wastewater; D014874:Water Pollutants, Chemical; C021106:azoreductase
keywords: Azo reductase; Cyclic voltammetry; Redox mediators; Sequencing Batch Reactor (SBR); Toxicity