What is a Dissolved Ozone Sensor and How It Works

Understanding Dissolved Ozone

Similar to dissolved oxygen, ozone is a gas at ambient conditions, but it can dissolve in water, forming dissolved ozone. The amount of ozone in water depends on several factors:

• Temperature

• Pressure

• Water chemistry (pH, ionic strength, organic content)

• Ozone generator output

Monitoring dissolved ozone is essential because its oxidizing power diminishes quickly due to decomposition and reaction with organic matter. This makes continuous measurement necessary in many processes.

Types of Dissolved Ozone Sensors

There are two primary technologies for measuring dissolved ozone:

1. Electrochemical (Membrane) Sensors

• Use a gas-permeable membrane and electrolyte.

• Ozone diffuses through the membrane and reacts at the electrode, producing a measurable current.

• Require periodic replacement of the membrane and electrolyte.

2. Optical (Luminescent) Sensors

• Use a luminophore-coated optical surface.

• Ozone quenches the luminescence of the dye.

• The sensor measures the change in light intensity or decay time to determine ozone concentration.

• Low maintenance and long lifespan compared to membrane sensors.

How Optical Dissolved Ozone Sensors Work

Optical dissolved ozone sensors rely on the interaction between ozone molecules and a luminescent dye embedded in the sensor tip.

1. Luminescent Layer: The sensor tip is coated with a luminophore that emits light when excited by a specific wavelength.

2. Ozone Quenching: When ozone molecules come in contact with the dye, the luminescence is partially quenched. The amount of quenching correlates directly with the ozone concentration in the water.

3. Detection: A photodetector measures the intensity or decay of emitted light. The sensor’s electronics convert this into a concentration reading.

4. Temperature Compensation: Most optical sensors include automatic temperature compensation to correct for changes in water temperature that can affect readings.

This method provides fast response, high accuracy, and low drift over time.

Applications of Dissolved Ozone Sensors

Dissolved ozone sensors are used wherever ozone is applied in water, including:

• Drinking water disinfection

• Wastewater treatment

• Aquaculture (keeping water safe for fish and other aquatic organisms)

• Food and beverage processing

• Industrial cleaning and sterilization processes

Advantages of Optical Dissolved Ozone Sensors

• Minimal maintenance: No membranes or electrolytes to replace.

• Fast response: Immediate readings allow real-time monitoring.

• Durable: Resistant to many harsh water conditions.

• High accuracy: Typically ±2–5% of reading.

Maintenance Tips

Even optical sensors require care for reliable operation:

• Clean the optical surface periodically to remove biofilm or scale.

• Calibrate the sensor every 3–6 months, depending on water quality.

• Replace the optical sensing cap every 1–2 years, depending on exposure and ozone concentration.

In Waboost we work with LH-DZ900 ozone sensor which is compatible with our Cloud application, therefore ozone dosing can be controlled via parameters that you set online.

If you have any question regarding ozone or ozone safety please feel free to reach out to us.