Abstract

CHEN, Y.; ZHU, Z.; YU, W.  and  ZHANG, C.. Granulation Process and Mechanism of Aerobic Granular Sludge under Salt Stress in a Sequencing Batch Reactor. Tecnol. cienc. agua [online]. 2019, vol.10, n.4, pp.156-181.  Epub Apr 21, 2021. ISSN 2007-2422.  https://doi.org/10.24850/j-tyca-2019-04-08.

The formation and characteristics of aerobic granular sludge (AGS) under different operational conditions in a sequencing batch reactor (SBR), designed to treat Mustard tuber wastewater (MTW, characterized as saline wastewater), had been investigated in this study. Morphology and structure during granulation were determined using a microscope with a digital camera and scanning electron microscope (SEM). Granules formed in the reactors could be classified as zoogloea granules with a clear boundary outline and filamentous granules with mycelia bestrewing boundary. Zoogloea granules, cultivated in reactor R1 and R2, was with higher density than filamentous granules, cultivated in reactor R3, and consequently had a higher settling velocity. Results showed that divalent metal ions such as Ca2+ and Mg2+ with phosphate in inflow could transform into precipitates, serving as crystal nucleus and carriers for granulation. Moreover, appropriate organic loading, hydrodynamic shear and salt-stress selection can induce moderate growth of filamentous bacteria to act as granulation backbone and consequently granulation process under salt stress was a result together with crystal nucleus, filamentous bacteria, and extracellular polymeric substances (EPS), which could be affected by salinity-shifting strategies and dosage of aluminum salt coagulant.

Keywords : aerobic granular sludge (AGS); salt stress; sequencing batch reactor (SBR); filamentous; extracellular polymeric substances (EPS).