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Morphological and structural characteristics of aerobic granulation
Author(s) -
Li Jiuyi,
Chen Yong,
Li Jin,
Zhang Donghua,
Wang Shuguang,
Wang Lianjun,
Jiang Dong,
Sun Feiyun,
Zhang Qiong
Publication year - 2006
Publication title -
journal of chemical technology and biotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.64
H-Index - 117
eISSN - 1097-4660
pISSN - 0268-2575
DOI - 10.1002/jctb.1491
Subject(s) - granulation , microorganism , settling , extracellular polymeric substance , segmented filamentous bacteria , mycelium , chemical engineering , bioreactor , oxygen , bacteria , chemistry , settling time , materials science , biology , biofilm , composite material , environmental engineering , environmental science , botany , wastewater , organic chemistry , genetics , activated sludge , engineering , control engineering , step response
Abstract The morphological and structural characteristics of aerobic granulation were investigated in a sequencing batch reactor. Small granules consisting mainly of bacterial microcolonies first formed at an organic loading rate of 1.68 kg chemical oxygen demand (COD) m −3 d −1 and a minimal settling velocity of 9.6 m h −1 . Mycelial granules consisting of fungi and filamentous microorganisms formed as the minimal settling velocity increased to 18 m h −1 . Scanning electronic microscopic observations indicated that fungi formed the structural backbone upon which other microorganisms can attach and colonize. The attached organisms began to reproduce themselves and quickly fill up the spatial voids within the granules. When the organic loading rate of the reactor increased to 4.2 kg COD m −3 d −1 , the granules exhibited a denser and more compact structure and bacteria with a variety of morphotypes, embedded in extracellular polymeric substances, dominated. When the aerobic filling time was extended from 5 to 30 min, the thick and compact granules were gradually shifted into a light and loose filamentous granular structure. The extension of the aerobic filling time eventually led to instability and the failure of reactor operation. Copyright © 2006 Society of Chemical Industry