Oxidation-Reduction Potential (ORP) Regulation as a Way to Optimize Aeration and C, N and P Removal: Experimental Basis and Various Full-Scale Examples

1989 ◽  
Vol 21 (10-11) ◽  
pp. 1209-1223 ◽  
Author(s):  
J. Charpentier ◽  
H. Godart ◽  
G. Martin ◽  
Y. Mogno
Keyword(s):  
Activated Sludge ◽  
Reduction Potential ◽  
Pilot Scale ◽  
Point Of View ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Winter Peak ◽  
Definition Of ◽  
Different Characteristics ◽  
P Removal

The control of aeration by measuring the oxidation reduction potential (ORP) of activated sludge, conducted at the YFFINIAC (West of France) sewage plant in 1983, showed this type of regulation to be attractive in that it can optimize energy costs and perfect the removal of carbonaceous and nitrogenous pollutants (CHARPENTIER et al, 1987). From a practical point of view, this new, inexpensive means of regulation has moreover proved easier to implement than the method based on measuring Dissolved Oxygen (D.O.). Before implementingthis process, we undertoook a pilot study that enabled us to make more accurate the ORP values for activated sludge that must be observed in order to achieve the satisfactory removal of carbonaceous and nitrogen pollutants. Furthermore, the ORP readings revealed points of inflection that can be used for regulation purposes. These have been related to the disappearance either of the ammonia or the nitrates with release of phosphates. The experience gained with 7 ORP regulating systems, most of them in operation now for several years, and installed in works with vastly different characteristics, shows that the range of ORP values used corresponds to the pilot-scale experiments. It also shows the attractive features of the ORP signal, compared with that of D.O., when used for the regulation and interpretation of the phenomena involved in the biological treatment. This type of regulation leads to improvements in the annual electricity balance, expressed in terms of kWh v. kg of treated BOD5, and has proved to be compatible with a programmed shutdown of the aerators during the winter peak hours when the tariff per kWh is particularly expensive. In conclusion, the diversity of experiments on site has largely contributed towards the definition of those practical methods upon which depends the success of the system.

scholarly journals On the mechanism of oxidation-reduction potential

1927 ◽  
Vol 101 (707) ◽  
pp. 57-70 ◽  
Keyword(s):  
Reduction Potential ◽  
Reduction Process ◽  
Point Of View ◽  
Biological Oxidation ◽  
Hydrogen Atoms ◽  
Oxidation Processes ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
The Subject ◽  
Mechanism Of Oxidation

The phenomena of oxidation-reduction potential are becoming increasingly important in the study of biological oxidation processes. Unfortunately, however, the application of the results obtained from studies on potential to such processes has been somewhat hindered by the fact that the study of potential phenomena has up to the present been approached from a point of view which differs considerably from that of the more important theories of the mechanism of biological oxidation processes. The conceptions used in the development of the two subjects have been different, and the close connection between the two sets of phenomena has thereby been obscured. For instance, Wieland’s theory, which has played such an important part in the development of the subject of biological oxidation processes, is founded on the conception of activation and transfer of hydrogen atoms, while Mansfield Clark, in his recent important and valuable studies on reduction-potential, makes use of conceptions such as electron activity, transfer of “ electron pairs,” and so on. This absence of “ linking up ” between the two sides of the subject has, in fact, been brought up as an objection to the Wieland view. For instance, Clark (3, 4) claims that the reduction-potential phenomena prove that the oxidation-reduction process consists essentially in the transfer of an electron pair from reductant to oxidant, and not in the transfer of hydrogen as assumed by Wieland. He regards this as a very serious objection to the Wieland theory, although possibly not sufficient entirely to disprove it. It must be pointed out, however, that the fact that the electron transfer hypothesis leads to correct results is no proof of its truth until the alternative hypotheses have been shown to yield incorrect results. In the present communication it is shown that the Wieland view also leads to correct results ; in fact, it is possible to predict the reduction-potential phenomena from the work of Wieland. This at once disposes of one of the main objections to Wieland’s theory and renders it possible to relate the mechanism of oxidation-reduction potential with that of biological oxidation-reduction processes.

Improving the sensitivity of the activated sludge respiration inhibition test and verifying the results using an oxidation-reduction potential electrode

2016 ◽  
Vol 75 (2) ◽  
pp. 247-254 ◽  
Author(s):  
F. Friedrichs ◽  
K. U. Rudolph ◽  
Bich Hanh Nguyen ◽  
D. Meinardi ◽  
W. Genthe ◽  
...  
Keyword(s):  
Activated Sludge ◽  
Oxygen Sensor ◽  
Reduction Potential ◽  
Treatment Plant ◽  
Inhibition Test ◽  
Synthetic Wastewater ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Potential Electrode ◽  
Nutrient Solutions

The inhibition of activated sludge respiration is one of the most important parameters for monitoring wastewater toxicity. The main objective of this study was to improve respiration inhibition testing in order to protect the biological degradation within the aerobic process in a wastewater treatment plant more efficiently. In order to influence the sensitivity of the testing bacteria, two different nutrient solutions were selected for biological testing, synthetic wastewater according to ISO 8192 and NaAc (sodium acetate). The effects of the nutrient solutions on heavy metal speciation and their respiration inhibition were investigated. The toxicants Zn(II), Cu(II), Cr(VI) and 3,5 DCP (3,5-dichlorophenol) were used as standards to determine toxicities and to study the influence of nutrient solutions. Results have shown that NaAc as a nutrient solution sensitized the respiration inhibition test up to a factor of 7.7. Furthermore, an oxidation reduction potential electrode can be used as an alternative tool to verify the results obtained with an oxygen sensor.

Influence of dissolved oxygen and oxidation–reduction potential on the denitrification rate of activated sludge

1994 ◽  
Vol 30 (6) ◽  
pp. 91-100 ◽  
Author(s):  
Ewa Lie ◽  
Thomas Welander
Keyword(s):  
Dissolved Oxygen ◽  
Activated Sludge ◽  
Reduction Potential ◽  
Inhibitory Effect ◽  
Denitrification Rate ◽  
Oxidation Reduction ◽  
Oxidation Reduction Potential ◽  
Low Concentrations ◽  
Denitrification Activity ◽  
Do Concentration

The influence of low concentrations of dissolved oxygen (DO) and the oxidation-reduction potential (ORP) on the denitrification activity of activated sludge has been studied in batchwise experiments. The ORP was maintained at different levels by automatic titration with air and the denitrification activity was determined by following the disappearance of nitrate. Oxygen was found to have a negative effect on denitrification even at lower concentrations than can be measured with conventional oxygen probes (<0.1 mg/L). The ORP was found to be a useful indicator of the DO concentration at this low level and the denitrification rate was found to decrease linearly with increasing ORP. However, the effect of the ORP on denitrification differed between sludges from different treatment plants. A linear relationship was also found between the ORP and the DO concentration in the region of measurable DO concentrations. Extrapolation of this straight line into the region where DO was under the detection limit indicated that oxygen exerts an inhibitory effect on denitrification at such low concentrations as a few μg/L.

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