Full-scale Study Of A Continuous-flow Intermittent Aeration Anoxic/oxic Bioreactor For Decentralized Wastewater Treatment

Abstract

A full-scale study was carried out with a continuous-flow intermittent aeration anoxic/oxic (A/O) bioreactor for small-flowrate decentralized wastewater treatment. During a nearly one-year operation monitoring and optimization period, different operation parameters including aeration time fraction, mixed liquor recycle ratio and hydraulic retention time (HRT) were examined for the removal efficiencies of chemical oxygen demand (COD), nitrogen and phosphorus. Results indicate that the bioreactor could maintain a high concentration of mixed liquor suspended solids, thus achieving a high COD removal. Nitrogen removal could be enhanced in the following ways: decreasing the aeration time fraction (i.e., increasing the non-aeration time) at a fixed influent flowrate; decreasing the mixed liquor recycle ratio at a fixed aeration intensity; or increasing both the aeration time fraction and cycle time for an increased influent flowrate. When the bioreactor reached steady-state conditions (wastewater temperature 17.4~28.6 ℃, aeration time fraction 0.5, mean DO concentration in the aeration stage about 1.0 mg·L-1, HRT 16.6 h, and mixed liquor recycle ratio 1.5), the removal efficiencies of COD, ammonia-nitrogen (NH4+-N), total nitrogen (TN) and total phosphorus (TP) could reach >90%, >90%, 70%~80% and >80%, respectively. The effluent COD, NH4+-N and TN concentrations could meet Level 1A standard while the effluent TP concentration could meet Level 1B standard, according to the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant (GB18918-2002).

Department(s)

Civil, Architectural and Environmental Engineering

Keywords and Phrases

Anoxic/oxic bioreactor; Decentralized wastewater treatment; Full-scale study; Intermittent aeration

International Standard Serial Number (ISSN)

0253-2468

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2025 Journal of Environmental Science, All rights reserved.

Publication Date

06 May 2018

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