Tristar Water Solutions

Tristar Water Solutions is able to offer a range of water sterilisation systems for potable and industrial water uses.

Depending on your desired outcome, water quality and purpose, Tristar can assist in helping identify the best form of sterilisation for your project or plant.

Why disinfect drinking water?

Disinfection kills or inactivates disease-causing organisms in a water supply and must provide a 99.9 percent inactivation of Giardia lamblia cysts and enteric viruses to protect health and to comply with the regulations. There are two kinds of disinfection: primary disinfection achieve the desired level of microorganism kill or inactivation, while secondary disinfection maintains disinfectant residual in the finished water that prevents the regrowth of microorganisms.

Some systems use a combination of disinfectants. For example, a system using UV for initial treatment may use chlorine for subsequent treatment to maintain disinfection "residual" in the water distribution system.

The following are the most commonly used sterilisation systems in the water and wastewater industry:

UV - Ultraviolet

Ultraviolet disinfection is a means of killing or rendering harmless microorganisms in a dedicated environment. These microorganisms can range from bacteria and viruses to algae and protozoa. UV disinfection is used in air and water purification, sewage treatment, protection of food and beverages, and many other disinfection and sterilization applications. This is accomplished through the conversion of electrical energy in a low pressure mercury vapor "hard glass" quartz lamp. Electrons flow through the ionized mercury vapor between the electrodes of the lamp, which then creates UV light. As UV light penetrates through the cell wall and cytoplasmic membrane, it causes a molecular rearrangement of the microorganism's DNA, which prevents it from reproducing. If the cell cannot reproduce, it is considered dead.

A major advantage of UV treatment is that it is capable of disinfecting water faster than chlorine without tanks and harmful chemicals. UV treatment systems can be extremely cost efficient.

Sodium Hypochlorite

Sodium Hypochlorite ( liquid chlorine )is one of the most commonly used and reliable sources of disinfection in package plants being used today. Sodium Hypochlorite is supplied in a liquid form in a 12.5% solution. The disinfection process starts with the ability to dose the sodium hypochlorite into the water .A relatively simple process starts with a storage tank where the water will recirculate mixing the sodium hypochlorite solution throughout the contents of the tank. An in line chlorine analyser or monitor will then be used to measure that the correct amount of sodium hypochlorite has then been contacted with the water.

The measuring of the amount of sodium hypochlorite in the water content allows it to ensure that it has received the right amount of sodium hypochlorite to effectively sterilise the contents of the tank. This is measured in form of ppm (parts per million).

Tristar can effectively supply complete packaged units with minimal operator involvement.

Ozone

Ozone is generated by dry air or oxygen being passed between two high-voltage electrodes. Ozone can also be generated photo chemically by ultraviolet light.

Some small systems utilize Ozone- generating U-V lamps. Larger systems usually utilize Corona Discharge technology. The ozone is highly effective in destroying pathogens, and when its work is completed, breaks down into oxygen (O2). This form of oxygen does not adversely affect the taste of the water. On the contrary, the added dissolved oxygen enhances the water's taste. Advantages include highly effective sterilisation, no unpleasant tastes or odours, and a significant residual effect. This makes ozone practical for almost any application, where price is not the key issue.

Ozone systems cost more than comparably sized U-V systems, but have several important advantages. The residual effect also makes ozone practical for applications where the treated water will be piped for relatively short distances Ozone is very useful for treating water stored in tanks prior to being dispensed, as with water stores or other water vending applications. A recirculation pump continuously draws water from the tank, ozonates the water, and pumps it back into the tank. Ozone must be delivered to a water system by injection through a contactor. The delivery rate is dependent on the mass transfer rate of this contactor or sparger. Proper maintenance of the generator and contactor is critical.

Chlorine Gas

Chlorine gas is widely used as the prime disinfecting ingredient in the Municipal Water Industry. It acts as a fast oxidising agent, treats organic taste and odour and produces a free chlorine residual. Due to the hazardous nature of chlorine gas the maintenance and operational staff of a chlorine plant need to be well trained personnel. The product has a Dangerous Goods Classification for storage, handling and transport.

Chlorine gas is released from a liquid chlorine cylinder by a pressure reducing and flow control valve operating at a pressure less than atmospheric. The gas is led to an injector in the water supply pipe where highly pressurised water is passed through a venturi orifice creating a vacuum that draws the chlorine into the water stream. Adequate mixing and contact time must be provided after injection to ensure complete disinfection of pathogens. It may be necessary to control the pH of the water. A basic system consists of a chlorine cylinder, a cylinder-mounted chlorine gas vacuum regulator, a chlorine gas injector, and a contact tank or pipe.