Ozone generators are extremely effective in disinfecting wastewater. In addition they potentially can remove pharmaceuticals and personal care products that can end up in drinking water by way of wastewater discharges. Ozone also helps to oxygenate the water before it is returned to rivers enhancing the overall health of the ecosystem.

Springfield Public Works wants to replace ozone generators at the Southwest Wastewater Treatment Plant. That would increase the facility’s capacity to disinfect from 65 million gallons a day to 100 million gallons a day. The generators are about 30 years old and replacement parts are expensive and difficult to come by. If the city had the new generators, it would likely save $4 million in operating costs in the next 20 years. Despite the increased difficulty to find parts, it is does demonstrate that high quality ozone generators can be expected to give extremely long lived operation.

Meyer said $3 million of the $16.2 million will be federal stimulus funds and the remaining $13.2 million will be a 20-year loan from the state’s revolving fund.

At the Southwest Wastewater Treatment Plant, money from the stimulus funds and state loan will be spent on a 24-month project to build a new ozone generator, expanding the facility’s capacity to disinfect up to 100 million gallons of treated water each day. Currently, the facility is limited to 60 million gallons, Meyer said.

“It’s a significant increase in what we can disinfect and treat,” Meyer said. “It will help up with our wet water flows and our peak flows.”

Fort Worth has recently begun construction of a 12 MGD facility at their Westside WTP site. The $47 MM project is being constructed by McCarthy Building Companies of Texas. The project will provide drinking water for western Fort Worth and is expanded to handle the future demand for water from that area of the region.

The plant will treat raw water from the Tarrant Regional Water Board raw water main that connects Eagle Mountain Lake with the East Texas water supply in Cedar Creek and Richland-Chambers reservoirs. The facilities include an ozone contact basin, flocculation and sedimentation basins, as well as filters and a membrane facility. The new water treatment plant will have an operations building, wash water recovery basins, a recycle pump station, a 2.5-million-gallon ground storage tank, a high-service pump station, an ozone generator building, an electrical building and related site and civil work.

This facility continues the tradition of expanding ozone use in the region. As will be noted from recent posts, ozone use continues to grow as more advanced drinking water treatment systems are deployed around the US.

As can be seen from other posts on this site, the use of ozone for municipal water treatment continues to grow with more and more cities around the country adding this technology to their mix.

The TPF XT can produce ozone from either air or oxygen. Configured for air feed, TPF XT series can produce ozone at 2-3 weight percent from 42 to 480 lbs/day. Using oxygen feed, ozone can be produced at 6-10 weight percent from 69-913 lbs/day. Power consumption is 9.5 kWh/kg of ozone produced. These systems, designed primarily for water treatment applications, can treat up to 50 million gallons per day of water for applications such as drinking water treatment.

The smaller MCP XT series can also produce ozone from air or oxygen. Configured for air feed, the MCP XT series can produce ozone at 2-3 weight percent from 2 to 37 lbs/day. Using oxygen feed, ozone can be produced at 6-10 weight percent from 4-69 lbs/day.

Both series employ IGBT electronics with PLC based controls. Components in contact with ozone are made of 316 L stainless or flouropolymers. The electrical components conform to CE, with UL rating available upon request. Air fed systems come with on board air dryers capable of achieving -70 degree C dew point feed gas.

Anthony Sacco, Marketing Director for Spartan, said: “Spartan is pleased to offer these high performance systems to our customers in the United States and Canada. With increasing interest in alternative water treatment technologies, these high efficiency ozone generators should offer water treatment companies additional options for water purification.”

Spartan Environmental Technologies is a supplier of ozone generators and integrated ozone and advanced oxidation systems for industrial and municipal water and wastewater treatment applications.

Ozono Elettronica Internazionale is a Milan (Italy) based manufacturer of ozone generators with over 35 years of experience in supply ozone generators and related equipment to the water treatment industry around the world.

In order to prevent this catastrophic failure, back flow prevention systems must be used. Given the potential damage possible, multiple protection devices are employed. The simplest is a check valve. While check valves are simple and inexpensive, they are not particularly reliable. Check valves are almost always used, but not as the sole method of protection. A new type of check valve using the hydrophobic properties of flouropolymers are being tested as a solid state check valve, but these devices have seen limited use to date.

Typically, ozone is introduced into pressurized lines by means of a venturi injector. The venturi creates a vacuum that draws the ozone gas into the liquid. If this vacuum is lost, it is possible that water could back flow. So, one protection method employed is a vacuum switch. When vacuum is lost a signal can be sent to a solenoid valve to close before water has a chance to flow towards the ozone generator. Alternatively, a pressure switch could be used if it is set below the pressure of the generator.

A third level of protection employed is a liquid trap. This device has a float that opens when water back flows into it. The float opens a line to drain to divert the back flowing water to the drain instead of the ozone generator. It is important to make sure that the materials in the liquid trap are compatible with ozone exposure.

A fourth level of protection is a sensor that detects liquid somewhere in the gas line between the venturi and the ozone generator. One such device employs ultra sonics. It has a forked sensor that can detect a difference between air and a liquid in the gap of the fork. This signal can be used to shut the solenoid valve protecting the ozone generator.

A well designed ozone water treatment system with ozone feed into a pressurized line should have at least two and probably three of these devices in place to protect the ozone generator. Spartan Environmental Technologies employs a three way protection system in its SPARTOX ozone water treatment system.

In terms of gas preparation, the main issues are moisture, hydrocarbons and particulates. Moisture lowers efficiency and can cause corrosion due to the formation of nitric acid in the generator. A good system for drying the gas is critical. For larger systems, it is wise to invest in dew point monitors to measure the level of moisture in the gas. Particulates and hydrocarbons can deposit on the electrodes in the generator impacting efficiency. They can also lead to heating of the electrodes with potential damage to the dielectrics.

If water enters the ozone generator catastrophic damage will be done to the system. So, it is critical that water be prevented from entering the unit during operation or during periods when the unit is not active.

In coming posts we will cover each of these factors impacting reliability in detail.