The Use of Oxidation-Reduction Potential as a Means of Controlling Effluent Ammonia Concentration in an Extended Aeration Activated Sludge System

Abstract

This study developed a strategy to control effluent ammonia from an activated sludge system, using oxidation-reduction potential. By controlling effluent ammonia concentrations, disinfection of treated wastewater is more cost effectively achieved by chloramination rather than break-point chlorination. The system under consideration was an extended aeration oxidation ditch. The study takes into account the concepts of nitrification and denitrification, as well as intrinsic characteristics of oxidation-reduction potential, while also keeping ease of operation in mind. Data were gathered by varying the rate of aeration of the basin from two extremes, while collecting samples along the timeline. Oxidation-reduction potential, dissolved oxygen concentration and ammonia concentration data were collected for evaluation. Using these data a preliminary control strategy was developed. The control strategy focused on operating the system in a continuous flow and varying aeration scenario. Two attempts to control the oxidation ditch were made. Using oxidation-reduction potential as an indicator, adjustments were made to the aerator controls in order to accommodate changes in organic loading, and maintain a constant effluent ammonia concentration. The first attempt was met with success and used to fine tune the strategy for the second attempt. The second attempt experienced more success than the first in controlling effluent ammonia concentrations, thus confirming the original hypothesis of the study.

Design, Operation and Optimization of Constructed Wetland for Removal of Pollutant

“…The situations in a reed bed model can be differentiated as per Szogi et al, [ 232 ] with regard to whether it is aerobic or anaerobic by DO and ORP measured data. Along with [ 233 , 234 ] the interaction between do as well as ORP is linear, meaning ORP also enhances as DO enhances. The DO rates vary from 5.8 ± 0.1 to 7.9 ± 0.0 ppm [ 230 ].…”

“…The DO rates vary from 5.8 ± 0.1 to 7.9 ± 0.0 ppm [ 230 ]. As the ORP reached −170 mV, 0 ppm DO densities happened [ 233 ]. The negative ORP indicates the machine is in a reduction condition as per Akkajit and Tongcumpou, [ 235 ].…”

Simultaneous removal of nutrients from milking parlor wastewater using an AO2sequencing batch reactor (SBR) system

“…[31] Heduit and Thevenot [32] stated that the platinum electrode potential at equilibrium (E h ) and the DO concentration would obey a form: E h D a x log [O 2 ] C b, at pH D 7, and the constants, a and b, mainly depended on the sludge loading, the aeration conditions and the sludge concentration. Following this line, in this study the ORP and logarithm of DO values in the two aerobic phases were plotted to verify the linear relationship.…”

Phytotoxicity and Uptake of Arsenic by Ludwigia octovalvis in a Pilot Reed Bed System

“…According to Szogi et al (2004), the conditions in a reed bed system can be distinguished with respect to whether it is aerobic or anaerobic through DO and ORP measurements. According to Myers et al (2006) and Ndegwa et al (2007), the relationship between DO and ORP is linear, that is, when DO increases, ORP also increases. The DO values ranged between 5.8 -0.1 and 7.9 -0.0 mg/L.…”

“…The DO values ranged between 5.8 -0.1 and 7.9 -0.0 mg/L. DO concentrations of 0 mg/L occurred as the ORP reached -170 mV (Myers et al, 2006). According to Akkajit and Tongcumpou (2010), the negative ORP shows the system is in a reducing state.…”