The concept of ORP in water treatment

1. Definition

ORP (oxidation reduction potential) is an important indicator of water quality. Although it cannot independently reflect the quality of water, it can integrate other water quality indicators to reflect the ecological environment in the aquarium system.

In water, every substance has its own redox characteristics. In simple terms, we can understand that at the microscopic level, each different substance has a certain oxidation-reduction ability, and these substances with different oxidation-reduction properties can influence each other, and finally constitute a certain macroscopic oxidation-reduction property. The so-called oxidation-reduction potential is used to reflect the macroscopic oxidation-reduction properties of all substances in the aqueous solution. The higher the oxidation-reduction potential, the stronger the oxidation, and the lower the potential, the weaker the oxidation. A positive potential indicates that the solution shows a certain degree of oxidation, and a negative potential indicates that the solution shows reduction.

2. Scope of application

2.1 Industrial wastewater treatment

The redox system used in water treatment is mainly the reduction of chromic acid and the oxidation of cyanide. If sodium disulfide or sulfur dioxide is added to the wastewater, the hexavalent chromium ions can be turned into trivalent chromium. If chlorine or sodium hypochlorite is added, it can be used to oxidize cyanide, followed by hydrolysis of cyanogen chloride to form cyanate. This chemical reaction process is called a redox reaction system. The oxidation-reduction potential is a measurement of electronic activity, which is very similar to the method of measuring hydrogen ion activity.

2.2 Water disinfection application

Redox electrodes can measure the disinfection effect of swimming pool water, mineral water and tap water. Because the bactericidal effect of coliforms in water is affected by the oxidation-reduction potential, the oxidation-reduction potential is a reliable indicator of water quality. If the oxidation-reduction potential value of pool water and mineral water is equal to or higher than 650mv, it means that the bacteria content is acceptable.

2.3 Soil ORP

Observe the dynamic changes of ORP in the soil, etc.

For example, after the paddy soil is irrigated to grow rice, the redox status of the soil has undergone drastic changes. There is a kind of paddy soil, which is generally maintained at 450-650mV before irrigation. The ORP drops rapidly after irrigation, and the ORP drops to minus 200mV to 100mV during the vigorous decomposition period of organic matter, and it can even drop to minus 300mV when a large amount of fresh green manure is applied. It will rise again later, generally maintained at 0-200mV. Before the rice was harvested, the soil fell dry and the ORP rose to more than 450 mV.

3. Understanding of Industrial Wastewater ORP

What is the oxidation-reduction potential? In water, every substance has its own redox characteristics. Simply we can understand it as: at the microscopic level, each different substance has a certain oxidation-reduction ability, and these substances with different oxidation-reduction properties can influence each other, and finally constitute a certain macroscopic oxidation-reduction ability. The so-called oxidation-reduction potential is used to react the macroscopic oxidation-reduction properties of all substances in the aqueous solution. The higher the oxidation-reduction potential, the stronger the oxidation, and the lower the potential, the weaker the oxidation. A positive potential indicates that the solution shows a certain degree of oxidation, and a negative potential indicates that the solution shows reduction.

Our filtration system removes denitrification, and is actually an oxidizing biochemical filtration device. For organic matter, microorganisms break longer carbon chains (or open various carbon rings) through oxidation, and then undergo a complex biochemical process to finally oxidize various forms of organic carbon to carbon dioxide; at the same time, these oxidations also The nitrogen, phosphorus, sulfur and other substances are disconnected from the corresponding carbon bonds to form the corresponding inorganic substances. For inorganic substances, microorganisms oxidize low-valence inorganic substances into high-valence substances through oxidation. This is the essence of oxidative biochemical filtration (here we only care about those substances that are oxidized and decomposed by microorganisms, and not those that are absorbed and assimilated by microorganisms). It can be seen that the substances in the water are continuously oxidized during the biochemical filtration. The process of biochemical oxidation is accompanied by the continuous generation of oxidation products, so from a macro point of view, the oxidation-reduction potential is continuously increased. Therefore, from this perspective, the higher the oxidation-reduction potential, the more thoroughly the pollutants in the water are filtered.