Over the past few years, product development and design improvements have led to the increased availability of energy efficient, high concentration ozone generators. The question that arose was how to efficiently mix the high concentration, low volume gas flow with the high volume water flows.
This question led to the development of a process from GDT Corp. that works most efficiently at low gas-to-liquid ratios. GDT has integrated the technology into a new packaged treatment, ozone contacting system.
The GDT(tm) process is primarily installed as a Side Stream configuration although full flow contacting can be achieved. A side stream flow is diverted from the pressurized main line in order to introduce ozone gas to the water. A water boost pump increases the pressure of the water to overcome the pressure loss as the water flows through the contact equipment and ultimately returns back to the main line.
Ozone gas is aspirated via a high efficiency Mazzei(r) injector. The ozone gas expands into the liquid, resulting in violent small bubble gas-liquid mixture. The dynamic mixing and mass transfer that occurs at the injector is enhanced in the reaction chamber specifically designed for each application. The reaction vessel operates under pressure. The higher the pressure the gas and liquid are under the more gas can be dissolved. The two-phase flow leaving the reaction vessel proceeds to the degas separator.
As the entrained gas/water mixture enters the degassing separator, it is accelerated to a velocity which exerts four to 10 times gravity in a lateral force, creating a water film at the separator wall and a gas vortex at the central, gas extraction core (tornado effect). This journey of a few seconds has the ability to extract between 95 and 98 percent of the entrained gases within the water stream. A degas relief valve discharges separated entrained gases for ozone destruct processing.
The resultant water stream leaving the degas separator contains high levels of dissolved ozone without any entrained gas. It is reintroduced to the main line water flow with the aid of a Mazzei(r) Mass Transfer Multiplier. The Mass Transfer Multiplier dynamically enhances the distribution of the dissolved ozone throughout the main line flow, ensuring a high ozone transfer.
While typically only 10 percent to 30 percent of the main flow is diverted into the side stream, the system achieves ozone mass transfer rates in excess of 95 percent.
A GDT representative, Caribbean Unlimited of Miami, Fla., recently has sold five of the ozone contact systems in Central America. A banana grower in San Salvador is using the system to treat well water for iron and manganese removal. The ozone oxidizes the metals prior to filtration. The processed filtered water is then used for rinsing the bananas before packaging and distribution to market. Another installation in El Salvador is used for taste and odor control in a bottled water facility. The pressurized contacting allows the system to be operated without need for additional transfer pumps to the filling equipment. Other Caribbean Unlimited installations for the skid-mounted system include potable and domestic applications.
