PRODUCTS > Ozone and Ultra Violet

Ozone Sanitizing – How It Works
The clean fresh smell evident after a lightning storm is ozone. Ozone is a very strong disinfectant and oxidizer. Any pathogen or contaminant that can be disinfected, altered or removed via an oxidation process will be affected by ozone. It is the strongest of all molecules available for disinfection in water treatment, and is second only to elemental fluorine in oxidizing power. Compared to chlorine, the most common water disinfection chemical, ozone is more than 50% stronger and acts over 3,000 times faster. Both chlorine and fluorine are highly toxic chemicals. Ozone is of particular value in water treatment systems because of its ability to disinfect without adding other chemicals which may later need to be removed. However, as with other treatment methods, the oxidized by-products of Ozonation will need to be removed by filtration or settling to provide acceptably clean clear water.

The Ozonation Process
The formation of oxygen into ozone occurs with the use of energy. This process is carried out by an electric discharge field as in the CD-type ozone generators (corona discharge simulation of lightning), or by ultraviolet radiation as in UV-type ozone generators (simulation of the ultraviolet rays from the sun). In addition to these commercial methods, ozone may also be made through electrolytic and chemical reactions. In general, an ozonation system includes passing dry, clean air through a high voltage electric discharge, i.e., corona discharge, which creates an ozone concentration of approximately 1% or 10,000 mg/L. In treating very small quantities, the UV ozonators are the most common, while large-scale systems use either corona discharge or other bulk ozone-producing methods.

Basic Water Sanitizing System
Ozone is produced on site using an ozone generator, and is injected into the water via aspiration (turbines or high speed agitators), eduction (venturi), or pumping (diffusers or fine air stones). It effectively treats the following contaminants: bacteria, viruses, inorganic minerals and dyes, iron, manganese and other metals, plankton, algae and other organics, toxins, and protozoa such as Cryptosporidium and Giardia. By comparison, at normal dosages, UV does not effectively disinfect these latter organisms since they require a higher dose. Ozone is also useful in removing colour and odour in water, and reducing turbidity. It reduces BOD and COD, and can prolong filter media life.

Ultra Violet Sanitizing – How It Works
UV sanitizing units are used in many water purification systems to control bacteria and viruses. They can be very effective water treatment tools if used correctly - although UV as a disinfecting tool has limitations, these can be minimised through correct installation and scheduled maintenance. UV energy can best be described as invisible radiation. UV energy penetrates the outer cell membrane of a micro organism in water, passes through the cell body, and disrupts its DNA, thereby preventing reproduction. Although 100% destruction of micro organisms cannot be guaranteed, it is possible to achieve a 99.9% reduction in certain applications with proper maintenance. In order for a UV unit to successfully disinfect water, it is important to have adequate water quality, a sufficient flow rate, and correct dosage. The dosage, a product of UV light intensity and exposure time, is measured in microwatt second per square centimetre (μws/cm²).

Most UV units are designed to provide a dosage greater than 30 000 μws/cm² after one year of continuous operation. Special low-pressure mercury vapour lamps produce ultraviolet radiation at 254 nm, the optimal wavelength for disinfection. The UV lamp never contacts the water. The lamp is either housed in a quartz glass sleeve inside the water chamber or it is mounted out of the water, and the water is forced through UV-transparent Teflon tubes. UV has some limitations: Certain contaminants in water can reduce the transmission or dosage of UV light through the water, which reduces the UV dose that reaches the bacteria. These UV-absorbing contaminants include turbidity, iron, and humic and fulvic acid (which are common to surface water supplies). Suspended particles are a problem because micro organisms buried within these particles are shielded from the UV light and pass through the unit unaffected.

All UV units have a maximum flow rate capacity and some have a minimum flow rate as well. If the flow is too high, water will pass through without enough UV exposure. If the flow is too low, heat may build up, causing damage to the UV lamp. UV units only “kill” bacteria at one point in a water system and do not “kill” bacteria further down the line. If just one bacterium passes through unharmed (100% destruction of bacteria cannot be guaranteed), there is nothing to prevent it from attaching to downstream piping surfaces and multiplying. In addition, the “dead” micro organisms and any other contaminants in the water are a food source for any bacteria that do survive downstream of the UV unit. For these reasons, it is imperative to perform regular maintenance on your water system. You should periodically sanitize the piping and storage tanks in a water system with a chemical disinfectant.

UV lamps do not burn out as normal florescent lamps do, but their intensity reduces over time. When lamps are new, they will generate a dosage level near 60 000 μws/ cm². When the dosage level drops to 30 000 μws/cm² (the minimum dosage needed to effectively kill bacteria) lamps should be replaced (approx 8000hrs). Water should be sampled and tested for bacteria counts regularly. Sample before and after the UV unit to test its performance. As water passes through the UV unit, minerals, debris, and other material in the water will leave deposits on the quartz sleeve or Teflon tube. This will limit the penetration of the UV rays. To maintain high clarity, the glass around the lamp must be cleaned regularly. Cleaning frequency depends on the water quality and will be less with reverse osmosis, distilled, or de-ionized water.

There are many sizes and models of both UV and Ozone systems available. Please contact us with your specific requirements.