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Mechanism of efficient nutrient removal and microbial analysis of a combined anaerobic baffled reactor–membrane bioreactor process
Wu, P.; Ji, X.; Song, X. & Shen, Y,
Abstract
A combined ABR–MBR process consisting of
an anaerobic baffled reactor (ABR) combined with an
aerobic membrane bioreactor (MBR) treating municipal
wastewater was investigated at controlled pH range 6.5–8.5
and at constant temperature 25 ± 1 °C. Total nitrogen
(TN), ammonia (NH4
?–N), total phosphorus (TP), and
chemical oxygen demand (COD) removal performances
were evaluated by analyzing the mechanism for efficient
nutrient removal. The results showed that the average
removal rates of COD, NH4
+–N, TN, and TP reached 93,
99, 79, and 92 %, respectively, corresponding with the
COD, NH4
+–N, TN, and TP effluent of 24 (18–31), 0.4
(0–0.8), 10.6 (8.8–12.9), and 0.31 (0.1–0.5) mg/L under the
operational condition of hydraulic retention time (HRT)
7.5 h, recycle ratio 200 %, and dissolved oxygen 3 mg/L.
The MBR enhanced NH4
+–N, TN, and TP removal rates of
13, 10, and 18 %, respectively, and the membrane retention
reduced TP 0.17 mg/L. The process was able to maintain a
stable performance with high-quality effluent. Analysis of
the results by fluorescence in situ hybridization showed
that the abundance of ammonia-oxidizing bacteria, nitriteoxidizing
bacteria, and phosphorus accumulating organisms
as percentages of all bacteria in each compartment
was stable. The enriched microorganisms in the system
appear to be the main drivers of the process efficient for
nutrient removal.
Keywords
Anaerobic processes; Aerobic processes; Membrane bioreactors; Optimization; Municipal wastewater; Nutrient removal
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