NO2-100 Nitrite Ion-Selective Electrode

Overview

The NO2-100 is a precision ion-selective electrode specifically designed for measuring nitrite (NO2⁻) concentration in water. Nitrite is an intermediate product in the nitrogen cycle and can be toxic to aquatic life at elevated levels. This sensor is critical for monitoring nitrification processes in aquaculture, wastewater treatment, and environmental water quality assessment.

Key Features

• High Selectivity: Specifically designed for nitrite ion detection
• Wide Range: Measures from 0.5 to 46,000 mg/L (ppm)
• Dual Output Options: Supports both RS485 Modbus RTU and 4-20mA current output
• Fast Response: Results within 30 seconds
• Automatic Temperature Compensation: Integrated PT1000 sensor for accurate readings
• Direct Connection: Connect directly to computer or PLC without additional instrumentation
• High Protection: IP68 waterproof rating ensures reliable operation

Applications

• Aquaculture biofilter monitoring
• Fish farming water quality
• Wastewater treatment plants
• Nitrification process control
• Drinking water treatment
• Environmental water monitoring
• Recirculating aquaculture systems (RAS)
• Aquarium water quality
• Groundwater contamination assessment
• Research and laboratory use

Technical Specifications

The NO2-100 delivers precise nitrite measurements from 0.5 to 46,000 mg/L with automatic temperature compensation via the integrated PT1000 sensor. The ion-selective membrane provides exceptional selectivity for nitrite ions, enabling early detection of nitrification issues.

Understanding Nitrite in Water

Nitrite is an intermediate nitrogen compound in the nitrogen cycle:

Nitrogen Cycle Position

1. Ammonia (NH3/NH4⁺): From organic matter decomposition
2. Nitrite (NO2⁻): Intermediate oxidation state (TOXIC)
3. Nitrate (NO3⁻): Final oxidation product

Toxicity Concerns

• Aquatic Life: Highly toxic to fish and invertebrates
• Mechanism: Interferes with oxygen transport in blood
• Brown Blood Disease: Causes methemoglobinemia in fish
• Sensitive Species: Shrimp particularly vulnerable

Aquaculture Safety Levels

• Safe: < 0.1 mg/L
• Caution: 0.1-0.5 mg/L
• Dangerous: > 0.5 mg/L
• Lethal: > 5 mg/L (varies by species)

Biofilter Monitoring

Nitrite monitoring is essential for biofilter management:

• Start-up Phase: Tracking nitrification establishment
• Nitrite Spike: Detecting biofilter disturbances
• Performance: Assessing biological filtration efficiency
• Recovery: Monitoring after system stress

Wastewater Treatment

In wastewater treatment, nitrite indicates:

• Nitrification Progress: Step 1 of biological nitrogen removal
• Process Problems: Incomplete nitrification
• Operational Issues: Dissolved oxygen or pH problems
• Inhibition: Presence of toxic compounds

Typical Nitrite Levels

• Natural water: < 0.001 mg/L
• Aquaculture (safe): < 0.1 mg/L
• Aquaculture (stress): > 0.5 mg/L
• Wastewater influent: 0-5 mg/L
• Nitrifying systems: Variable during start-up
• Drinking water limit: 1 mg/L (EPA standard)

Connectivity and Integration

With its RS485 Modbus RTU interface, the NO2-100 seamlessly integrates into modern SCADA systems, aquaculture monitoring platforms, and IoT networks. The 4-20mA current output option ensures compatibility with traditional controllers and alarm systems.

Installation and Maintenance

The NO2-100 requires regular calibration with standard nitrite solutions for optimal accuracy. The sensor should be cleaned periodically to prevent biofouling. The robust IP68-rated construction allows for continuous immersion in aquaculture and wastewater systems.

Nitrogen Cycle Monitoring

For complete nitrogen cycle monitoring, combine with:

• NH4-100: Ammonium levels
• NH3-100: Toxic ammonia
• NO3-100: Nitrate end product
• NOx-100: Total nitrogen oxides