title: Characterization of aerobic granules by microbial density at different COD loading rates.
abstract: Aerobic granules were cultivated under temporal alternating aerobic and anoxic conditions without the presence of a carrier material in a sequencing batch reactor (SBR) with a high column height/column diameter ratio. The reactor was operated for 6h per cycle (aerobic: 4.75 h, anoxic: 1.25 h). To determine a new parameter for the definition of aerobic granules, a protocol of 4,6-diamidino-2-phenylindole hydrochloride staining and fluorescence image processing was developed. The d(tm) analysis showed that the increase in the chemical oxygen demand (COD) loading rate promoted no more growth of the aerobic granules. It was inconsistent with the results of the analysis of the sludge volume index (SVI) value but matched well with the results of the COD and nitrogen removal of the SBR and the particle size distribution by LS-PSA. The optimum COD loading rate for aerobic granulation in the SBR was 2.52 kg/m(3)d. When d(tm) was correlated with the biomass concentration and the SVI value during the period of granule formation, d(tm) could be used as a more sensitive and accurate parameter for classifying aerobic granules and optimizing the operational conditions for aerobic granulation processes.
authors.affiliation: Department of Environmental Science and Engineering, Gwangju Institute of Science and Technology (GIST), 1 Oryong-dong, Buk-gu, Gwangju, Republic of Korea. iskim@gist.ac.kr
authors.forename: In S
authors.initials: IS
authors.lastname: Kim
authors.forename: Sung-Min
authors.initials: SM
authors.lastname: Kim
authors.forename: Am
authors.initials: A
authors.lastname: Jang
mesh_terms: D000641:Ammonia / Q000302:isolation & purification; D001420:Bacteria, Aerobic / Q000737:chemistry / Q000378:metabolism*; D018533:Biomass; D019149:Bioreactors; D005456:Fluorescent Dyes; D000860:Hypoxia / Q000378:metabolism; D007211:Indoles; D018613:Microscopy, Confocal; D009584:Nitrogen / Q000302:isolation & purification; D010100:Oxygen / Q000378:metabolism*; D010316:Particle Size; D012722:Sewage / Q000382:microbiology; D013997:Time Factors
chemical_list: D005456:Fluorescent Dyes; D007211:Indoles; D012722:Sewage; C007293:DAPI; D000641:Ammonia; D009584:Nitrogen; D010100:Oxygen