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Electroflotation clarifier to enhance nitrogen removal in a two-stage alternating aeration bioreactor

Cho, Kangwoo and Chung, Chong Min and Kim, Yun Jung and Hoffmann, Michael R. and Chung, Tai Hak (2013) Electroflotation clarifier to enhance nitrogen removal in a two-stage alternating aeration bioreactor. Environmental Technology, 34 (19). pp. 2765-2772. ISSN 0959-3330. https://resolver.caltech.edu/CaltechAUTHORS:20131204-133521300

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Abstract

Stringent water treatment criteria and rapidly growing pollutant loads provoke the demand for retrofitting wastewater treatment plants towards a higher capacity. In this study, we assess a two stage alternating aeration (AA) bioreactor equipped with electroflotation (EF) clarifier, for nitrogen removal within a short hydraulic reTENTion time (HRT). The EF under steady solids loading required a minimum unit height and gas:solids ratio of 0.006 for efficient clarification. The separated sludge blanket was further thickened with retaining stability when the cyclic solids loading was smaller than 1.0 kg m^(−2). In the continuous operation of the bioreactor, the returned activated sludge concentration increased to more than 18,000 mg L^(−1), while the effluent suspended solids concentration was lowered below 5 mg L^(−1). Under influent chemical oxygen demand (COD)/total inorganic nitrogen (TIN) concentration of 300/30 mg L^(−1), the TIN removal efficiency was near 70% with cycle time ratios of 0.17 and 0.27. Under higher influent COD concentration of 500 mg L^(−1), TIN removal efficiency was found to be 73.4% at a carbon:nitrogen (C:N) ratio of 10 and even higher (80.4%) at a C:N ratio of 16.6. The increased mixed liquor suspended solids concentrations (>6000 mg L^(−1)) under the high COD loading were efficiently maintained by using the EF clarifier. The results of this study demonstrate that an EF clarifier with a HRT of less than 1 h can support reliable nitrogen removal in the AA process that has a HRT of 6 h, even under increasing influent loadings.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1080/09593330.2013.788072 DOIArticle
http://www.tandfonline.com/doi/abs/10.1080/09593330.2013.788072#PublisherArticle
ORCID:
AuthorORCID
Hoffmann, Michael R.0000-0001-6495-1946
Additional Information:© 2013 Taylor & Francis. Received 18 September 20 12; final version received 13 March 2013. Accepted author version posted online: 20 May 2013. Published online: 24 May 2013. The authors would like to acknowledge the financial supports by the Korea Institute of Science and Technology (KIST), Bill and Melinda Gates Foundation (Reinvent the Toilet Challenge Grant OPP I 03 7491) and SNU SIR Group of the BK21 research programme funded by Ministry of Education and Human Resources Development.
Funders:
Funding AgencyGrant Number
Korea Institute of Science and Technology (KIST)UNSPECIFIED
Bill and Melinda Gates FoundationOPP1037491
Ministry of Education and Human Resources DevelopmentUNSPECIFIED
SNU SIR Group of the BK21 Research ProgrammeUNSPECIFIED
Subject Keywords:wastewater treatment; alternating aeration bioreactor; electroflotation; activated sludge; nitrogen removal
Issue or Number:19
Record Number:CaltechAUTHORS:20131204-133521300
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20131204-133521300
Official Citation:Electroflotation clarifier to enhance nitrogen removal in a two-stage alternating aeration bioreactor Kangwoo Cho, Chong Min Chung, Yun Jung Kim, Michael R. Hoffmann & Tai Hak Chung pages 2765-2772
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:42832
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:04 Dec 2013 21:56
Last Modified:03 Mar 2020 13:01

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