DS500 Series Online Chemical Oxygen Demand COD Sensor from OPS is a next-generation, eco-friendly solution for water quality monitoring. With no reagents required, it creates zero secondary pollution—making it both cost-effective and environmentally responsible. Its compact design allows for quick installation, while real-time online monitoring ensures continuous oversight of water quality. Featuring automatic turbidity compensation and a self-cleaning function, the DS500 delivers long-term stability with minimal maintenance.

Measuring Principle

The DS500 series is built on advanced UV absorption technology. Since many organic substances in water absorb ultraviolet light at 254 nm, the sensor can accurately measure the levels of organic pollution. To ensure precision, the DS500 uses a dual-light source—254 nm UV and 850 nm infrared—which automatically corrects for turbidity and optical path disturbances. The result is highly stable, reliable readings. By capturing organics in multiple dimensions, the DS500 provides stronger correlations with key indicators such as BOD, COD, and TSS, giving you a more complete and accurate picture of water quality.

Key Features of the Online COD Sensor

Eco-Friendly & Cost-Saving: Works without reagents—no chemicals, no pollution, just a smarter and greener solution.

All-in-One Monitoring: Measure COD, BOD, TSS, TOC, and more with a single sensor.

Reliable Accuracy: Automatic turbidity compensation ensures clear, dependable results every time.

Fast & Efficient: Advanced optical technology delivers quick, stable, and exact measurements.

RS-485 Output Signal: It is equipped with an RS-485 interface that allows easy and fast sensor configuration via Modbus. It can be easily connected to a monitoring system. DSMC5100 can be equipped with it to read real-time monitoring data, and the data storage function provides users with a basis for analyzing the data.

Technical Parameter

Specifications

DS500 COD Sensor Installation Cases

Applications Of  COD Sensors

COD sensors play a vital role across a wide range of industries and environmental management sectors. Below are some of the key areas where they are commonly used:

-Wastewater Treatment Plants
Treatment facilities use COD sensors to continuously monitor incoming wastewater and verify that the treated effluent meets regulatory standards. Accurate COD measurements allow operators to fine-tune processes and reduce pollution effectively.

-Industrial Effluent Monitoring
Industries such as food processing, textiles, and chemicals generate significant wastewater. COD sensors help these facilities monitor effluent quality and ensure compliance with environmental regulations before discharge.

-Environmental Monitoring
Government and environmental agencies deploy COD sensors to track pollution levels in rivers, lakes, and coastal waters. Elevated COD readings can signal the presence of harmful organic pollutants that threaten aquatic ecosystems.

-Municipal Water Systems
Municipalities use COD sensors to safeguard both drinking water and wastewater systems. Monitoring COD levels helps detect organic contamination early, enabling timely corrective action to maintain public health and water quality.

-Aquaculture
In fish farming and other aquaculture operations, COD sensors are essential for maintaining healthy water conditions. High COD levels may indicate deteriorating water quality that could endanger aquatic life.

Advantages of Using COD Sensors

COD sensors provide significant benefits for both industries and environmental monitoring organizations. Some of the key advantages include:

Real-Time Data: Continuous, real-time monitoring enables faster and more informed decision-making in wastewater treatment plants and industrial operations.

Cost Efficiency: Regular monitoring helps facilities avoid costly fines and penalties by ensuring compliance with environmental regulations.

High Accuracy: Advanced COD sensors deliver precise measurements, minimizing errors and improving the reliability of water quality assessments.

Automation-Friendly: Modern COD sensors can be seamlessly integrated into automated systems, simplifying the management of large-scale water treatment processes.

Installation

Calibration of DS500 COD Sensors

Step 1: Select the theoretical value according to the range, e.g., if the range is 100mg/l, then choose 12 for theoretical value 1; choose 84 for theoretical value 2.

Step 2: Before starting this, Reset K=1, B=0. Put the sensor into the test solution of 12mg/l, wait for the test data to stabilize, then enter the average value of the measured value as the measured value 1. Place the sensor in another test solution of 84mg/l, wait for the test data to stabilize, and enter the average of the measured values as the measured value 2.

Step 3: Click OK via the calibration help software. You will get the new K, B values, and save the new K, B values in the testing software.

COD calibration is completed.

FAQs About COD Sensor

1, What Is COD and BOD?

COD (Chemical Oxygen Demand) measures the total quantity of oxygen required to chemically oxidize organic and inorganic substances in water.

BOD (Biochemical Oxygen Demand) measures the amount of oxygen that microorganisms consume while breaking down organic matter in water over a period (usually 5 days at 20°C).

Chemical Oxygen Demand (COD) and Biological Oxygen Demand (BOD) are essential parameters used to measure the organic pollution in water bodies. COD quantifies the amount of oxygen required to chemically oxidize organic matter in water, using strong chemical oxidants under acidic conditions. It provides a measure of the total organic content, including both biodegradable and non-biodegradable organic matter.

BOD measures the amount of oxygen consumed by microorganisms to biologically decompose organic matter in water over a specific period, typically 5 days (BOD5). It indicates the biodegradable organic content and is a key indicator of water quality, reflecting the potential for oxygen depletion in aquatic environments.

Both COD and BOD are crucial for assessing the impact of wastewater and industrial effluents on receiving water bodies. High levels of COD and BOD can lead to eutrophication, depletion of dissolved oxygen, and adverse effects on aquatic life. Monitoring these parameters helps in managing wastewater treatment processes and ensuring compliance with environmental regulations.

2, What is BOD vs COD vs TOC?

BOD (Biochemical Oxygen Demand): Indicates the biologically degradable portion of organic matter.

COD (Chemical Oxygen Demand): Represents both biodegradable and non-biodegradable (but oxidizable) organics.

TOC (Total Organic Carbon): Measures all carbon in organic compounds; doesn’t directly reflect oxygen demand but gives insight into organic pollution.

3, Why Do We Measure COD in Water?

We measure Chemical Oxygen Demand (COD) in water because it’s a critical indicator of water quality and helps in multiple key areas. Here’s how it connects to each of the points you listed:

• Pollution Control:

-COD measures the amount of oxygen required to chemically oxidize organic and inorganic matter in water.

-High COD indicates high pollution levels—often from industrial discharges or sewage—helping authorities track pollution sources.

• Wastewater Treatment

-COD testing helps assess how effective a treatment process is at removing organic matter.

-It’s often used alongside BOD (Biochemical Oxygen Demand) to monitor treatment efficiency and process performance.

• Regulatory Compliance

-Environmental agencies set COD limits for effluent discharge into natural water bodies.

-Industries and treatment plants must regularly test COD to ensure their discharge meets legal requirements.

• Environmental Impact Assessment

-COD data provides insight into the potential impact of a discharge or activity on aquatic ecosystems.

-It’s used during project planning to predict and minimize harm to nearby water bodies.

• Water Quality Management

-Authorities monitor COD to manage and maintain healthy water systems—rivers, lakes, reservoirs, etc.

-It helps in prioritizing clean-up operations and resource allocation.

• Resource Management

-By tracking COD, water managers can determine the availability of clean water for reuse, irrigation, industrial use, or recreation.

-It supports the sustainable use of water resources, especially in water-scarce regions.

4, What is a COD Sensor?

A COD sensor is a device used to measure the Chemical Oxygen Demand (COD) in water, typically through UV-visible light absorption or reagent-based methods. These sensors enable real-time monitoring of organic pollution levels. A high COD value indicates a significant presence of organic pollutants that consume oxygen during decomposition, making it a key parameter for assessing water quality.

COD sensors have become indispensable for industries that manage wastewater, including manufacturing plants, power stations, and water treatment facilities. By continuously monitoring COD levels, these industries can evaluate water quality, optimize treatment processes, and ensure compliance with environmental regulations before discharging water back into the environment.

5, What is UV254?

UV254 is a water quality test parameter that quickly measures the organic matter in water. The measurement technique works by shining ultraviolet light (UV) at 254 nm through a quartz cell that contains a representative water sample. Most commonly, the cell is 1 cm (10 mm) but can vary depending on the application and water quality.

Organic compounds, specifically those that contain aromatic rings or unsaturated carbon bonds (double or triple) in their molecular structure, absorb a portion of the UV light as it passes through the water sample. Since the intensity of the light source is known, a detector on the other side of the cell is used to measure the amount of light absorbed by organic compounds present in the sample.

UV254 is typically expressed as either UV absorbance (UVA) per cm (cm-1) or UV transmittance (UVT) %. In some cases, UV254 is referred to as the Spectral Absorption Coefficient (SAC254).

UV254 and UVT are both valuable water quality measurements for many applications, including UV disinfection performance monitoring, raw water monitoring for event detection, coagulation control, and DBP precursor monitoring. The measurement method is simplistic and does not involve the use of reagents. There are multiple ways in which UV254 or UVT can be measured, including: continuously in real-time with a bypass analyzer or submersible probe sensor, grab samples throughout the plant with a portable test meter, or in the laboratory with a test meter or benchtop spectrophotometer.

6, Why is COD Higher Than BOD in Wastewater?

COD includes all chemically oxidizable substances, both biodegradable and non-biodegradable.

BOD measures only the oxygen used by microbes to break down biodegradable material.

Therefore, COD is typically higher than BOD, especially in industrial wastewater or where non-biodegradable organics are present.

7, Why is measuring Chemical Oxygen Demand (COD) essential in water quality monitoring?

COD represents the amount of oxygen required to chemically oxidize organic compounds present in a water sample. It serves as a critical indicator of the concentration of organic pollutants, providing insight into the potential impact on aquatic ecosystems and the efficiency of wastewater treatment processes. By quantifying the oxygen demand, COD measurements help evaluate organic load, assess compliance with environmental regulations, and guide operational adjustments in industrial and municipal treatment systems.

8, How to Choose the Right COD Sensor?

Choosing the right COD sensor depends on several factors, including the application, water quality, and budget. Here are some factors to consider:

-Water Quality

If you’re dealing with very dirty or polluted water, an optical COD sensor might be the better choice as it can handle a wider range of pollutants. For cleaner water or industrial applications, electrochemical sensors may offer better precision.

-Measurement Range:

Ensure that the sensor can measure the COD levels you expect to encounter in your water samples.

-Installation Type

COD sensors can either be inline (placed directly into the water stream) or offline (where samples are taken for analysis). Inline sensors are better for continuous monitoring, while offline sensors might be more suited for periodic checks.

-Budget

Optical COD sensors tend to be more expensive than electrochemical ones but may require less maintenance in the long run. Evaluate both upfront costs and ongoing maintenance expenses when choosing a sensor.

-Maintenance Requirements

Consider how often the sensor will need maintenance or calibration. Some COD sensors, especially electrochemical models, require more frequent maintenance, while optical sensors tend to need less attention.

-Data Integration

Many modern COD sensors come with digital output options, making it easier to integrate them with SCADA (Supervisory Control and Data Acquisition) systems or other digital monitoring systems.

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