title: The effects of aerobic/anoxic period sequence on aerobic granulation and COD/N treatment efficiency.
abstract: The effects of period sequence (anoxic-aerobic and aerobic-anoxic) on aerobic granulation from suspended seed sludge, and COD, N removal efficiencies were investigated in two sequencing batch reactors. More stable granules with greater sizes (1.8-3.5mm) were developed in R1 (anoxic-aerobic sequence). Yet, no significant difference was observed between the reactors in terms of removal efficiencies. Under optimum operational conditions, 92-95% COD, 89-90% TAN and 38-46% total nitrogen removal efficiencies were achieved. The anoxic-aerobic period sequence (R1) resulted in almost complete denitrification during anoxic periods while aerobic-anoxic sequence (R2) led to nitrate accumulation due to limited-carbon source and further granule disintegration. NH3-N concentration of 15-28 mg/L was found to inhibit COD removal up to 30%. This study also revealed the inhibitory sulfide production during anoxic periods. Sulfate concentration of 52.6-70.2mg/L was found to promote sulfate reduction and sulfide generation (0.24-0.62 mg/L) which, together with free-ammonia, inhibited TAN oxidation by 10-50%.
authors.affiliation: Environmental Engineering Department, Middle East Technical University, Ankara, Turkey; Environmental Engineering Department, Abdullah Gul University, Kayseri, Turkey.
authors.forename: Yusuf Çağatay
authors.initials: YÇ
authors.lastname: Erşan
authors.forename: Tuba Hande
authors.initials: TH
authors.lastname: Erguder
mesh_terms: D000332:Aerobiosis; D000641:Ammonia / Q000032:analysis; D000693:Anaerobiosis; D057919:Biological Oxygen Demand Analysis; D019149:Bioreactors / Q000382:microbiology; D058440:Denitrification; D005110:Extracellular Space / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D058465:Nitrification; D009584:Nitrogen / Q000302:isolation & purification*; D010316:Particle Size; D011134:Polysaccharides / Q000737:chemistry; D012722:Sewage / Q000737:chemistry*; D013431:Sulfates / Q000032:analysis; D013440:Sulfides / Q000032:analysis; D018508:Water Purification / Q000379:methods*
chemical_list: D011134:Polysaccharides; D012722:Sewage; D013431:Sulfates; D013440:Sulfides; D000641:Ammonia; D009584:Nitrogen
keywords: Extracellular polymeric substance (EPS); Granule; Inhibition; Simultaneous nitrification–denitrification