Core Sensing Equipment for Water Environment Quality Monitoring

Dissolved oxygen (DO) refers to the oxygen content dissolved in water. It is a core water quality indicator for assessing the self-purification capacity of water bodies and the health of aquatic ecosystems. In scenarios such as aquaculture production, river and lake ecological restoration, and biochemical process control in wastewater treatment, dissolved oxygen levels directly reflect the quality of the water environment. Traditional iodometric testing requires on-site sampling and return to the laboratory for analysis, a cumbersome process that cannot achieve in-situ, uninterrupted online monitoring. Dissolved oxygen sensors, also called dissolved oxygen transmitters, mainly utilize two technical approaches: electrochemical Clarke membrane electrode and fluorescence optical methods. The probe can be directly immersed in the water to output dissolved oxygen concentration in real time, making it an indispensable sensing hardware terminal for online water quality monitoring systems.

Measurement Principles and Core Advantages

Currently, the mainstream online water quality monitoring market includes two technical solutions: electrochemical and fluorescence methods. Their working principles and applicable conditions differ:

1. Electrochemical Dissolved Oxygen Sensor (Clark Membrane Electrode)

Based on the principle of redox reaction, oxygen permeates through the permeable membrane into the internal electrolyte, undergoing an electrochemical reaction on the electrode surface, outputting a current signal proportional to the dissolved oxygen concentration. The product has a lower purchase cost; however, the measurement process consumes oxygen in the water, requiring a certain water flow rate. The permeable membrane and electrolyte are consumable parts, requiring regular replacement and maintenance.

2. Fluorescence (Optical) Dissolved Oxygen Sensor

Relying on the fluorescence quenching effect, blue light illuminates the fluorescent membrane at the top of the probe, exciting the fluorescent material to produce red light. Oxygen molecules inside the water quench the fluorescence signal; the higher the dissolved oxygen concentration, the shorter the fluorescence decay time. The device collects the fluorescence lifetime signal and, in conjunction with temperature, air pressure, and salinity compensation algorithms, calculates the dissolved oxygen concentration. The measurement process does not consume oxygen, can be stably measured even in static water bodies, requires no electrolyte, and involves minimal maintenance, making it the mainstream choice for long-term online monitoring in the field.

Five Core Application Scenarios

1. Smart Aquaculture Monitoring: Real-time monitoring of dissolved oxygen in fish, shrimp, and crab ponds and offshore cages, triggering the start and stop of aeration equipment to prevent large-scale aquatic mortality caused by oxygen deficiency and improve aquaculture economic efficiency.

2. Wastewater Treatment Plant Process Control: Online monitoring of dissolved oxygen in aeration tanks guides the adjustment of aeration fan output, ensuring the effectiveness of biological treatment while saving aeration energy consumption.

3. River, Lake, and Reservoir Water Ecosystem Monitoring: Buoy monitoring stations in rivers, lakes, and reservoirs assess eutrophication levels, providing data support for water ecosystem restoration and water environment assessment.

4. Drinking Water Source and Groundwater Monitoring: Water quality monitoring at water sources and groundwater points assesses the reoxygenation status of water bodies, ensuring the safety of water supply quality.

5. Environmental Emergency and Scientific Research Investigation: Water body surveys and emergency sewage discharge investigations; rapid in-situ acquisition of dissolved oxygen data to support environmental assessments.

Industry Development Value and Future Trends: 

Dissolved oxygen sensors address the pain points of poor timeliness and inability to continuously monitor in situ in traditional laboratory testing, driving water environment monitoring towards grid-based and automated approaches. The industry is iteratively upgrading towards multi-parameter integration, low-power buoy integration, and AI-based biofouling identification. Future products will integrate dissolved oxygen, pH, conductivity, and turbidity; low-power wireless sensors will be widely adopted; and edge algorithms will be used to identify biofouling and membrane aging faults on probes, providing robust water quality sensing data support for smart aquaculture, river and lake ecological restoration, and intelligent operation and maintenance of wastewater treatment.