Efficacy of anaerobic membrane bioreactor under intermittent liquid circulation and its potential energy saving against a conventional activated sludge for industrial wastewater treatment

초록

Anaerobic membrane bioreactor (AnMBR) was employed as a secondary treatment unit for anaerobically treated wastewater from a full-scale digester of a fish canning factory. A lab-scale hollow fiber membrane AnMBR was operated at various intermittent liquid circulation (ILC) levels using granular activated carbon (GAC) as a moving media within the reactor, at a hydraulic retention time of 8 h. The experiment was aimed to investigate the effect of ILC with ON/OFF time-interval ratios of 15/15, 30/15, 45/15 (minute/minute) versus continuous circulation. Results showed that all reactors achieved chemical oxygen demand (COD) removal above 84% while nitrogen removals of only 31.5e41.5% were attained without biological nitrification/denitrification. The overall membrane fouling rate, a change of trans membrane pressure over time, was effectively controlled in higher ILC conditions, i.e., 21.6, 10.5, 7.2 and 3.6 mbar/day at 15/15, 30/15, 45/15 ILC and continuous liquid circulation, respectively. Analyses of resistance revealed that a larger contribution by cake layer formation was found at higher ILC which was related to its morphology by SEM. Finally, the energy requirement and COD removal efficiency were compared against the activated sludge process currently used at the canning factory. The analysis suggests a sizable energy saving with the anaerobic membrane process.(c) 2021 Elsevier Ltd. All rights reserved.

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