When taking samples, there are several field measurements that are noted; one of them is the Oxidation-Reduction Potential (ORP) of the water. This measures the capacity of the water to release or accept electrons from chemical reactions (Bier, 2009). When the system is accepting electrons it is oxidizing and when it is releasing electrons it is a reducing system (Bier, 2009). Examples of oxidation include rusting metal or a browning apple. The ORP of a system can be affected by numerous factors including the solids, new species, or concentration changes.
ORP is measured in millivolts (mV) using a sensor with two electrodes. The ORP electrode either accepts or donates electrons into the water, depending on the system. The reference electrode has a stable output of electrons as a comparison. The ORP is calculated using these two values. A positive value indicates the presence of oxidizing agents whereas a negative value points to contamination (Lowry & Dickman, 2013).
ORP is measured in millivolts (mV) using a sensor with two electrodes. The ORP electrode either accepts or donates electrons into the water, depending on the system. The reference electrode has a stable output of electrons as a comparison. The ORP is calculated using these two values. A positive value indicates the presence of oxidizing agents whereas a negative value points to contamination (Lowry & Dickman, 2013).
Examples of liquids and their ORP value [Source: https://healthykangenwater.files.wordpress.com/2010/10/orp-blog1.jpg]
The ORP of a washwater system is important as an oxidizing chemical can take electrons from a cell membrane which causes it to become leaky and damages it to the point where the cell dies (Suslow, 2004). Sensors can be deployed along washing systems for automated sensing of ORP and dispensing of oxidizing disinfectants (Suslow, 2004).
ORP is not presently a parameter of interest for discharge water. It plays a role during washing of vegetables as research has shown that the higher the ORP, the lower the survival time of certain decay, spoilage, and pathogenic bacteria (Suslow, 2004).
References
ORP is not presently a parameter of interest for discharge water. It plays a role during washing of vegetables as research has shown that the higher the ORP, the lower the survival time of certain decay, spoilage, and pathogenic bacteria (Suslow, 2004).
References
- Bier, A. W. (2009). Introduction to oxidation reduction potential measurement. In Hach Company. Retrieved March 2, 2015, from www.hach.com/asset-get.download.jsa?id=7639984590
- Lowry, R. W., & Dickman, D. (2013). The ABC's of ORP: Clearing up some of the mystery of oxidation-reduction potential. InService Industry News. Retrieved March 4, 2015, from http://www.rhtubs.com/ORP.htm
- Suslow, T. V. (2004). Oxidation-reduction potential (ORP) for water disinfection monitoring, control, and documentation. InUniversity of California Division of Agriculture and Natural Resources. Retrieved March 2, 2015, from http://anrcatalog.ucdavis.edu/pdf/8149.pdf
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