title: Start-up of sequencing batch reactor with Thiosphaera pantotropha for treatment of high-strength nitrogenous wastewater and sludge characterization.
abstract: Biological treatment of high-strength nitrogenous wastewater is challenging due to low growth rate of autotrophic nitrifiers. This study reports bioaugmentation of Thiosphaera pantotropha capable of simultaneously performing heterotrophic nitrification and aerobic denitrification (SND) in sequencing batch reactors (SBRs). SBRs fed with 1:1 organic-nitrogen (N) and NH4+-N were started up with activated sludge and T. pantotropha by gradual increase in N concentration. Sludge bulking problems initially observed could be overcome through improved aeration and mixing and change in carbon source. N removal decreased with increase in initial nitrogen concentration, and only 50-60 % removal could be achieved at the highest N concentration of 1000 mg L-1at 12-h cycle time. SND accounted for 28 % nitrogen loss. Reducing the settling time to 5-10 min and addition of divalent metal ions gradually improved the settling characteristics of sludge. Sludge aggregates of 0.05-0.2 mm diameter, much smaller than typical aerobic granules, were formed and progressive increase in settling velocity, specific gravity, Ca2+, Mg2+, protein, and polysaccharides was observed over time. Granulation facilitated total nitrogen (TN) removal at a constant rate over the entire 12-h cycle and thus increased TN removal up to 70 %. Concentrations of NO2--N and NO3--N were consistently low indicating effective denitrification. Nitrogen removal was possibly limited by urea hydrolysis/nitrification. Presence of T. pantotropha in the SBRs was confirmed through biochemical tests and 16S rDNA analysis.
authors.affiliation: Centre for Environmental Science and Engineering (CESE), Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
authors.forename: Pranita S
authors.initials: PS
authors.lastname: Phatak
authors.affiliation: Centre for Environmental Science and Engineering (CESE), Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
authors.forename: Saurabh
authors.initials: S
authors.lastname: Trivedi
authors.affiliation: Centre for Environmental Science and Engineering (CESE), Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
authors.forename: Anurag
authors.initials: A
authors.lastname: Garg
authors.affiliation: Centre for Environmental Science and Engineering (CESE), Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India.
authors.forename: Sudhir K
authors.initials: SK
authors.lastname: Gupta
authors.affiliation: Centre for Environmental Science and Engineering (CESE), Indian Institute of Technology Bombay, Powai, Mumbai, 400076, India. mitras@iitb.ac.in.
authors.forename: Suparna
authors.identifier: http://orcid.org/0000-0001-5722-3369
authors.initials: S
authors.lastname: Mukherji
mesh_terms: D019149:Bioreactors; D002244:Carbon / Q000378:metabolism; D058440:Denitrification; D052836:Heterotrophic Processes; D058465:Nitrification; D009584:Nitrogen / Q000032:analysis*; D042084:Paracoccus pantotrophus / Q000254:growth & development* / Q000378:metabolism; D012722:Sewage / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis*; D018508:Water Purification / Q000379:methods*
chemical_list: D002244:Carbon; D009584:Nitrogen; D012722:Sewage; D062065:Wastewater; D014874:Water Pollutants, Chemical
keywords: Acclimatization; Granulation; Sequencing batch reactor; Settling velocity; Simultaneous nitrification denitrification; Sludge volume index; Thiosphaera pantotropha