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A novel gravity selector was firstly introduced between the aerobic zone and clarifier in an anaerobic/anoxic/oxic (A(2)/O) reactor to reduce severe filamentous sludge bulking to limited filamentous bulking (LFB). By regulating the aeration periods of operation cycles of the selector and other parameters, lighter filamentous bulking sludge was gradually washed out, reducing the sludge volume index (SVI) from 418 to 210 mL/g. A stable LFB state was achieved in 80 d with pollutant removal efficiencies of 90.1%, 93.7%, 87.9% and 88.5% for COD, NH4+-N, TP and TN, respectively. Thiothrix and Beggiatoa, with extended filaments, dominated the filamentous bacterial population of the first phase, whereas Haliscomenobacter hydrossis, with ingrown, thin, and short filaments, dominated the LFB state. Therefore, the bulking control of the gravity selector relied on the different settling velocities of bacteria with different filament morphologies during sedimentation periods in the gravity field. The bacteria with long, outstretched filaments settled slowly and were preferentially washed out via the upper outlet. The LFB state was realised at low DO contents of 0.5 similar to 1.0 mg/L and a long sludge retention time (SRT) of 28 d with considerable denitrifying dephosphatation, indicating that the gravity selector can improve pollutant removal and energy utilisation.
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DESALINATION AND WATER TREATMENT
ISSN: 1944-3994
Year: 2018
Volume: 135
Page: 177-187
1 . 1 0 0
JCR@2022
ESI Discipline: ENGINEERING;
ESI HC Threshold:156
JCR Journal Grade:3
Cited Count:
WoS CC Cited Count: 5
SCOPUS Cited Count: 5
ESI Highly Cited Papers on the List: 0 Unfold All
WanFang Cited Count:
Chinese Cited Count:
30 Days PV: 2