Assessment of sludge reduction and microbial dynamics in an OSA process with short anaerobic retention time

This study operated for 160 days and evaluated sludge minimization using an oxic-settling-anaerobic (OSA) system fed with real wastewater. At first, a pilot-scale conventional activated sludge (CAS) system was used to perform conventional wastewater treatment over a course of 60 days. Next, the CAS...

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Bibliographic Details
Published in:	Environmental technology & innovation Vol. 19; p. 101025
Main Authors:	Martins, C.L., Velho, V.F., Magnus, B.S., Xavier, J.A., Guimarães, L.B., Leite, W.R., Costa, R.H.R.
Format:	Journal Article
Language:	English
Published:	Elsevier B.V 01-08-2020
Subjects:	Biomass activity Methane potential Microbial community Nitrogen removal Oxic-settling-anaerobic process Sludge minimization Nitrogen removal Biomass activity Sludge minimization Methane potential Oxic-settling-anaerobic process Microbial community
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Summary:	This study operated for 160 days and evaluated sludge minimization using an oxic-settling-anaerobic (OSA) system fed with real wastewater. At first, a pilot-scale conventional activated sludge (CAS) system was used to perform conventional wastewater treatment over a course of 60 days. Next, the CAS system was coupled with a sludge holding tank (SHT) in the sludge recirculation line to employ the OSA system, using a short 12h-hydraulic retention time (HRT) over a course of 100 days. The observed sludge yield (Yobs) dropped from 0.33 (CAS) to 0.19 (OSA) kg TSS kg−1 COD, ensuring a reduction of 43% of sludge in the OSA system. Better wastewater treatment performance was achieved using the OSA system (BOD5: 87%, TKN: 92%, NH4+-N: 94%) when compared with the CAS system (BOD5: 76%, TKN: 74%, NH4+-N: 78%), considering the organic matter and nitrogen removal rates. Moreover, the enrichment of anaerobic and hydrolyzing communities in the SHT (mainly Pedobacter and Acidovorax) enhanced the COD and nitrogen hydrolysis, which therefore improved the autotrophic metabolism in the aeration tank. [Display omitted] •OSA process was used to reduce the sludge production in an activated sludge system.•A short 12h HRT in the sludge holding tank was used to limit microbial growth.•Biomass reduction was 43% without hindering the treated effluent quality.•Pedobacter and Acidovorax supported the sludge reduction in the OSA process.•Anaerobic hydrolysis of COD and N-org improved aerobic autotrophic activity.
ISSN:	2352-1864 2352-1864
DOI:	10.1016/j.eti.2020.101025