Automated ozone dosage is controlled primarily through ORP (Oxidation-Reduction-Potential), which is a measurement of how much oxidant is in solution . Purifico offers the flexibility to program dosage based on schedule and/or ORP to suit various systems and irrigation strategies.
There are many ways to measure ozone depending on the application, precision needed, budget and practical considerations. For in-line measurement of ozone in water treatment systems, ORP (oxidation reduction potential) probes are typically used. Sensors that provide direct measurement of ozone concentrations in ppm are available, however they are costly and inaccurate in impure water, making them unsuitable for most applications outside the laboratory. Dissolved ozone concentrations can also be measured through methods such as titration or colorimetric assays, however these measurements need to be performed manually and so cannot be integrated into automated processes. The indigo colorimetric method is useful for the occasional manual monitoring residual ozone levels. Samples can be taken from various points in your irrigation system, to monitor and assess system functionality. These tests are inexpensive, easy to perform and informative. Purifico can supply these tests and provide instructions.
ORP provides an indirect measurement of ozone levels in your water, since it measures the overall tendency for oxidative (loss of electron) or reductive (gain of electron) reactions to occur in solution. This means that any oxidizing or reducing agent will affect ORP values. If ozone is the only oxidant added to solution, then it is safe to assume that any changes to ORP are resulting from ozone. ORP is typically measured in millivolts (mV), where positive values corresponding to oxidative conditions. Automatic dosage of ozone to maintain ORP within a specific range is used to ensure that disinfection is effective at all times. The probes used to measure ORP are the most cost-effective and durable option to monitor and control ozone dosage in automated systems.
Ozone and oxygen are both oxidants, and so ORP levels increase when they are injected into water. Low-quality water is typically anaerobic and has ORP levels <200mV. For agricultural water, effective disinfection usually occurs around 600mV and sterilization at around 800mV. When ozone is first injected into water, there is a delay before ORP starts rising. This is because ORP measures the overall oxidative state of the water, and initially the ozone is consumed at a high rate while it reacts with contaminants. As contaminants are removed and water purity increases, more ozone is able to accumulate in solution and ORP will increase. At high ORP levels, even the most hardy microbes are destroyed. Since ozone is a short-lived compound, these elevated ORP levels will quickly diminish after ozone injection is ceased. Our high-output ozone systems are able to treat water in-line, in tanks, and in large reservoirs such as dugouts or small lakes.
