Development and Implementation of a Real-Time Control System for Nitrogen Removal Using OUR and ORP as End Points

Abstract

This paper presents the development and implementation of a real-time control strategy based on end-point detection of biological reactions responsible for carbon and nitrogen removal in order to optimize the sequencing batch reactor (SBR) process. The control system is an algorithm that automatically adjusts the cycle length to the influent wastewater characteristics according to the end points. The algorithm acts in the reaction phases of the SBR cycle using the oxygen uptake rate (OUR) and oxidation−reduction potential (ORP) values as the aerobic and anoxic phase end points, respectively. Real-time control was employed in the 1-m3 pilot-plant SBR treating urban wastewater with some industrial components. Despite the influent variability, the effluent levels, 57 mg of COD·L-1 and 4.7 mg of N·L-1, were lower than those of the European Directive 91/217/CEE. These results demonstrate that the real-time control, using a conventional online ORP probe and the respirometer measurement, OUR, can be applied in the SBR to wastewater treatment.

Operational strategy for a partial nitritation–sequencing batch reactor treating urban landfill leachate to achieve a stable influent for an anammox reactor

“…Total nitrogen was calculated as the sum of N-TKN, nitrite and nitrate concentrations, as mg N-TN L −1 ). The calculation of the offline oxygen uptake rate (OUR, mg O 2 L −1 h −1 ) was based on the oxygen mass balance in a well-mixed region of the PN-SBR, in accordance with Puig et al 20 As long as the oxygen concentration in the reactor was controlled by an ON/OFF control, OUR was calculated when no aeration was conducted from the decrease in DO as a function of time. For this specific case, it was assumed that the dissolved oxygen contribution of the inflow was negligible.…”

Progress in the Development of Control Strategies for the SBR Process

“…Control strategies based on two indirect parameters: control strategies based on two indirect parameters are generally based on DO, pH, ORP, and OUR. There are 16 such strategies in theory, but most studies conducted to date have focused on either ORP and pH type strategies [62][63][64][65][66][67][68][69][70][71][72], ORP and OUR type strategies [73,74], ORP and DO type strategies [75], and pH and DO type strategies [76,77]. Of these, ORP and pH type strategies are the most commonly applied, while the others are relatively rare.…”

Modified calibration protocol evaluated in a model-based testing of SBR flexibility

“…A reference scenario (fixed cycle configuration and fixed DO set point) was compared with two RTCS that use the OUR (oxygen uptake rate) as a key variable to control the process [21][22][23]. simple architecture of one input and one output.…”