Ozone Mixing System

What an Ozone Mixing System Does

Ozone is used in bottled water production for microbial control in finished water and for continued disinfection after filling. When ozonated water enters a 3/5-gallon bottle, residual ozone can continue to contact the bottle interior and the inner surface of the cap during and after capping.

The engineering challenge is not only generating ozone. Ozone must be dissolved into water, mixed into the main finished-water flow, stored in an ozonated finished-water buffer tank, monitored at representative control points, and adjusted through PLC feedback. Without this system-level control, ozone residual at the filling point may be unstable even if the ozone generator itself is operating.

Why an Ozone Generator Alone Is Not Enough

An ozone generator only produces ozone. It does not guarantee dissolved ozone residual at the filling nozzle. In actual operation, dissolved ozone can be affected by water temperature, flow conditions, buffer tank level, pipeline length, holding time, start-stop status, and the amount of reducing substances or organic matter in the water.

For this reason, 4R does not treat the ozone system as “an ozone generator plus one injection point.” It is designed as a process section that includes ozone generation, gas-liquid dissolution, liquid-liquid static mixing, ozonated finished-water buffering, online dissolved ozone monitoring, PLC feedback, and ozone off-gas safety handling.

• Dissolution: Ozone gas must be transferred into water efficiently before it can function as dissolved ozone.
• Mixing: Ozonated side-stream water must be distributed into the main finished-water flow before entering the buffer tank.
• Buffer supply: The finished-water buffer tank separates front-end water treatment and ozone mixing from downstream intermittent or peak water demand.
• Use-point control: The target is stable residual ozone at the final use point, not simply a fixed ozone generator output.
• Risk management: Proper mixing and feedback control help avoid unnecessary over-dosing and unstable ozone peaks, especially when bromide is present in the source water.

Typical Process Position

In a bottled water plant, the ozone mixing system is placed after front-end finished-water treatment such as RO, MF, UF, or other membrane treatment. After gas-liquid mixing and static mixing, the ozonated finished water enters a buffer tank and is then supplied to downstream users such as the filling machine, internal washer finished-water final rinse, and online water-quality monitoring points.

• Front-end water treatment: RO, MF, UF, or other finished-water treatment process supplies treated water to the ozone mixing section.
• Gas-liquid ozone mixing: Ozone gas is brought into intensive contact with a water side-stream to improve dissolution.
• Liquid-liquid static mixing: Ozonated side-stream water is mixed into the main finished-water flow before entering the buffer tank.
• Ozonated finished-water buffer tank: The tank receives mixed ozonated finished water and provides stable supply to downstream users.
• Final use points: Ozonated water may be supplied to the filling machine, filling nozzle, internal washer finished-water final rinse, and online water-quality monitoring points.

Two-Stage Ozone Mixing

4R uses a two-stage mixing logic. The first stage focuses on transferring ozone from gas into water. The second stage focuses on distributing the ozonated water into the main finished-water flow. This structure helps reduce undissolved ozone carryover, local concentration difference, and unstable downstream ozone residual.

Ozonated Finished-Water Buffer Tank

The finished-water buffer tank is located after gas-liquid mixing and liquid-liquid static mixing. It receives already mixed ozonated finished water and supplies downstream users such as the filling machine, internal washer finished-water final rinse, and online water-quality monitoring points.

This tank is not the main mixer. Its core function is to provide stable water supply between front-end water treatment and downstream intermittent or peak water demand. Filling machines and final-rinse users do not always consume water at a constant rate. Without a buffer tank, downstream flow fluctuation may directly disturb ozone mixing, online measurement, and PLC feedback control.

After ozonated water enters the tank, ozone still continues to volatilize, escape, decay, and react with oxidizable substances in water. Therefore, ozone residual normally decreases from the buffer tank to the filling pipe and filling nozzle. 4R controls this expected decline instead of assuming that every point in the system has the same ozone concentration.

System Operation Animation

The ozone mixing station should be understood as a complete control module rather than a single injection point. The system prepares ozonated finished water, buffers it, monitors actual dissolved ozone concentration, and connects with the bottled water line.

Online Dissolved Ozone Monitoring and PLC Feedback

4R uses online dissolved ozone measurement as the core feedback signal. The online dissolved ozone analyzer sends the actual concentration value to the PLC. The PLC compares the measured value with the target set point and adjusts the ozone generator output.

This control method is different from operating the ozone generator at a fixed output and hoping the downstream residual remains stable. The selected monitoring point should reflect the actual control objective, such as the buffer tank outlet, filler inlet, filling nozzle, or another representative point selected during project design.

• Measured value: Actual dissolved ozone concentration at the selected monitoring point.
• Control method: PLC feedback compares measured concentration with the target set point.
• Controlled output: The ozone generator output is adjusted to bring residual ozone back into the target range.
• Alarm logic: The system may include high ozone alarm, low ozone alarm, sensor fault alarm, no-flow protection, and ozone generator status monitoring.
• Design condition: Sensor selection, sampling point, flow stability, calibration, and maintenance access must be considered during project design.

Bromate Risk and Ozone Control

Ozone is useful for microbial control, but it is not simply a “more is better” chemical. If the source water contains bromide, ozonation may form bromate, a regulated disinfection by-product in bottled water and drinking water standards.

Its value is that it helps the plant avoid unnecessary ozone over-dosing, poor mixing, and unstable ozone concentration peaks. For water sources that contain bromide, bromide testing, target ozone residual setting, and periodic bromate verification should be included in the water-quality control plan.

• Avoid unnecessary over-dosing: Stable feedback control reduces the need to raise ozone generator output just to compensate for unstable residual at the filling point.
• Reduce local long-time ozone peaks: Proper gas-liquid dissolution and liquid-liquid static mixing help avoid local high ozone zones that may increase oxidation pressure.
• Verify bromide and bromate: For bromide-containing water sources, bromide testing and periodic bromate verification should be handled as part of the quality-control plan.

Finished-Water Tank Breather and Ozone Off-Gas Safety

Ozonated finished water stored in the buffer tank releases part of its dissolved ozone into the gas space above the water. Because ozone gas is strongly oxidative, it should not be allowed to accumulate around operators or equipment.

4R configures a heated breather on the top of the finished-water buffer tank. The breather provides controlled high-temperature heating so that escaped ozone can be rapidly decomposed. The top of the breather is open to a pipe that discharges outside the plant.

The breather temperature can be set on the touch screen and controlled automatically. If the temperature fails or does not reach the required setting, the system triggers an alarm.

Integration with Water Treatment and 3/5-Gallon Bottling Lines

4R does not design the ozone mixing system as an isolated dosing skid. It must be integrated with the front-end finished-water treatment process and the downstream 3/5-gallon bottling line. The design should consider water treatment output, buffer tank capacity, filling-machine peak demand, internal washer final-rinse demand, ozone residual monitoring, conductivity monitoring, CIP logic, and start-stop protection.

• Front-end connection: RO, MF, UF, or other finished-water treatment process affects ozone consumption, residual stability, and bromate risk.
• Ozone mixing system: The system includes ozone generation, gas-liquid mixing, static mixing, finished-water buffer tank, online ozone monitoring, PLC feedback, and heated-breather safety discharge.
• Downstream use points: Ozonated water may supply the filling machine, internal washer finished-water final rinse, and online water-quality monitoring points.
• Quality-control points: Ozone residual, conductivity, and other finished-water quality indicators should be reviewed according to the plant’s control plan.
• Line interlocks: The system should coordinate with filling, final rinse, CIP, no-flow status, and start-stop protection logic.

Typical System Modules

What 4R Needs to Configure the System

Ozone mixing must be matched to the plant’s real water quality, bottling capacity, water-use points, and control target. To configure the system correctly, 4R usually reviews the following project information.

• Front-end water treatment: RO, MF, UF, or other finished-water treatment process, including water quality and operating flow.
• Bottling capacity: Target filling capacity, filling-machine peak water demand, and start-stop frequency.
• Finished-water buffer tank: Tank capacity, liquid-level fluctuation, downstream supply logic, and hydraulic buffer requirement.
• Final-rinse demand: Internal washer finished-water final rinse flow, timing, and whether separate ozone mixing is required for rinse water.
• Water quality risk: Bromide level, bromate risk, pH, temperature, and reducing-substance content that may consume ozone.
• Control point: Target ozone residual at the filling nozzle, filler inlet, buffer tank outlet, or other representative monitoring point.
• Monitoring requirements: Online ozone residual, conductivity, and other finished-water quality-control indicators required by the plant.
• Safety and exhaust: Breather heating, outdoor discharge pipe, operator access, alarm logic, and plant ventilation conditions.