NH₄-N Sensor & Controller

Advanced ISE-based Ammonium Nitrogen (NH₄-N) monitoring solution for real-time Total Ammonia Nitrogen (TAN) analysis in wastewater and industrial process control.

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Next-Gen ISE Technology for NH₄-N Monitoring

Reagent-Free Ammonia Detection

Utilizing advanced Ion Selective Electrode (ISE) technology to provide continuous NH₄-N monitoring without any chemical reagent consumption or costly waste disposal.

Wide-Range Industrial Capability

Delivers a broad measurement range of 0–1000 mg/L with a high resolution of 0.01 mg/L, making it ideal for both municipal wastewater and high-concentration industrial processes.

Integrated Multi-Ion Compensation

Features built-in pH and temperature electrodes with optional Potassium (K⁺) ion compensation to eliminate interference and ensure accuracy within ±5% of the measured value.

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Technical Specifications & Direct Support for NH351 NH₄-N Sensors

Download the complete datasheet for detailed ion-selective parameters or request a customized quote for your specific wastewater and industrial monitoring requirements.

Rugged & Versatile NH₄-N Probe

Constructed with a rugged IP68-rated POM housing, this digital ammonia probe is engineered to withstand high-pressure environments up to 2 bars and corrosive wastewater conditions for long-term field reliability.

Featuring a compact all-in-one design with a standard 1-inch NPT thread, our NH₄-N sensor allows for effortless submerged or pipe-mounting in confined industrial spaces without requiring heavy bypass systems.

Digital Ammonia Nitrogen Analyzer

This DUC2-NH4 digital controller is designed for single-channel digital ammonia sensors, supporting NH4-N and NH4+ measurements up to 1000 mg/L with auto-switching resolution. It features two configurable 0/4–20 mA outputs, an RS485 MODBUS interface, and two SPST relays for alarm or wash control.
The unit offers IP66 protection and supports wall, pipe, or panel mounting with a ABS enclosure. It includes power-off parameter retention, historical data logging (last 100 calibrations), and accepts AC 100–240V or DC 18–36V input with ~24W consumption.

Global Case Studies: Proven Performance in Diverse NH4-N Monitoring Environments

About Ammonium Nitrogen (NH₄-N)

The sensor operates by measuring the potential difference across a selective membrane as ammonium ions (NH₄⁺) interact with the electrode, providing a direct and continuous signal without chemical reagents. This ISE-based methodology is critical for capturing rapid ammonia spikes that traditional grab sampling misses, ensuring immediate response to process upsets. By integrating real-time pH and temperature compensation, the system mathematically corrects for the NH₃/NH₄⁺ equilibrium shift, maintaining measurement integrity across varying industrial water conditions.

The scientific principle of online ammonium nitrogen NH₄-N measurement primarily utilizes advanced ion-selective electrode (ISE) technology to determine real-time concentration levels in water. The measurement framework relies on a specialized PVC-based potentiometric selective membrane embedded with nonactin carrier molecules, which selectively bind with ammonium ions NH₄⁺ while restricting background interferents. As NH₄⁺ ions accumulate at the membrane boundary, a phase-boundary potential difference is established against the internal silver/silver chloride (Ag/AgCl) reference system, generating a millivolt (mV) output that strictly follows the logarithmic Nernst equation.

To ensure high accuracy in complex industrial effluents and wastewater treatment plants (WWTP), the system must dynamically address chemical equilibrium and ionic cross-sensitivity. Because the ratio between ionized ammonium NH₄⁺ and toxic unionized ammonia NH₃ shifts continuously depending on the water matrix, integrated intelligent transmitters execute real-time pH and temperature compensation algorithms to mathematically calculate the total NH₄-N values. Furthermore, since potassium ions K⁺ possess a similar ionic radius and interfere with the electrode, a dedicated potassium-selective electrode is deployed alongside the probe to perform real-time background subtraction, guaranteeing precise continuous monitoring and reliable aeration loop control.

Precise ammonium nitrogen (NH₄-N) monitoring is critical for preventing aquatic eutrophication and toxic algal blooms, ensuring the long-term protection of global water biodiversity. By optimizing nitrification processes, real-time data allows facilities to significantly reduce their carbon footprint and energy consumption, aligning industrial operations with global net-zero sustainability goals. Maintaining strict ammonia compliance not only secures the safety of water resources but also mitigates legal risks associated with increasingly stringent international environmental discharge standards.

Frequently Asked Questions

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1. What is the difference between NH₄ and NH₄-N?
NH₄ represents the total weight of the ammonium ion, while NH₄-N specifically measures the concentration of nitrogen present in the ammonium form, which is the standard metric for environmental regulatory compliance.
2. How does pH affect ammonium nitrogen (NH₄-N) measurement?
As pH increases, the chemical equilibrium shifts from ionized ammonium (NH₄⁺) to toxic unionized ammonia (NH₃); therefore, our sensors integrate real-time pH compensation to ensure accurate total NH₄-N readings.
3. What is the best method for continuous online NH₄⁻N monitoring?
The Ion-Selective Electrode (ISE) method is widely considered the best for online use because it provides real-time, reagent-free data with significantly lower maintenance costs compared to traditional colorimetric analyzers.
4. How often should an online NH₄⁻N ISE sensor be calibrated?
For most industrial and municipal wastewater applications, we recommend a simple two-point calibration every 2 to 4 weeks, depending on the organic loading and fouling potential of the water matrix.
5. Can NH₄⁻N sensors be used in seawater or high-salinity aquaculture?
Yes, specifically designed sensors like the NH351-K utilize advanced potassium (K⁺) ion compensation to eliminate interference from salinity, making them ideal for recirculating aquaculture systems (RAS).
6. What is the response time (T90) for the NH351 series sensor?
The NH351 series features a rapid T90 response time of less than 2 minutes, allowing for precise real-time feedback control of aeration and chemical dosing in nitrification tanks.
7. How do I prevent biofilm buildup on the ammonium sensor membrane?
Our sensors feature an integrated automatic self-cleaning brush that periodically sweeps the electrode surface, effectively preventing biofilm and mineral scaling without manual intervention.
8. What are the typical discharge limits for ammonium nitrogen in wastewater?
While limits vary by region (e.g., EPA or EU standards), many industrial facilities must maintain NH₄-N levels below 1-5 mg/L to prevent eutrophication and avoid heavy environmental regulatory fines.