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Conflict of Interest: In relation to this article, we declare that there is no conflict of interest.

Publication history: Received October 23, 2012
Accepted May 14, 2013

This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/bync/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Application of real-time feedback control strategies based on effluent NH4-N and NOX-N concentrations in an A2/O process

Hyosoo Kim Yejin Kim Trung Quang Hoang Gyeongdong Baek¹ Sungshin Kim² Changwon Kim^†

Department of Civil and Environmental Eng., Pusan National University, Busan 609-735, Korea ¹Daewoo Shipbuilding & Marine Engineering, Co., Ltd., Gyeonsangnam-do 656-714, Korea ²Department of Electrical Engineering, Pusan National University, Busan 609-735, Korea

cwkim@pusan.ac.kr

Korean Journal of Chemical Engineering, August 2013, 30(8), 1578-1587(10), 10.1007/s11814-013-0084-x

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Abstract

This paper proposes two real-time feedback control strategies based on hourly measurements of effluent NH4-N and NOX-N concentrations. Using modified sigmoid functions to decide the DO setpoint, a control structure similar to the cascade-type control loop was selected as the real-time feedback NH4-N control strategy. For the realtime feedback NOX-N control strategy, a proper external carbon dose flow rate could be calculated based on the estimated NOX-N concentration in anoxic reactor by using the empirical equation. A control system, which included two proposed control strategies, was developed and applied in the pilot-scale A2/O process. As a result, the effluent NH4-N and NOX-N concentrations were maintained stably lower than the target values of 3 and 5 mg/L, respectively. Moreover, because the manipulated variables for removing the NH4-N and NOX-N concentrations were divided in the control strategies, the two different control strategies could be successfully applied together in the A2/O process.

Keywords

Real-time Feedback NH4-N Control Strategy Real-time Feedback NOX-N Control Strategy Modified Sigmoid Function Empirical Equation A2/O Process

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