MS3500 - Ammonia Monitor for Wastewater

Robust and Reliable Technology

Used to monitor the wastewater plant intake

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Ammonia monitor
MS3500 ammonia Monitor

This product is under redevelopment and not available for purchase at the moment.

The MS3500 is the first ammonia monitor for Raw Waste Water. Its rugged construction and design allows it to reliably measure Ammonia at the very front end of a waste water treatment plant, giving the operator a level of control and knowledge presently unknown to the industry.


  • Monitor Raw Wastewater Intakes
  • Detect high loads of ammonia at the intake
  • Optimize the use of compressors and blowers in the aeration lanes
  • Analyze ammonia at the effluent
  • Analyze ammonia in the aeration lanes
  • Identify sources of ammonia discahrges

Features and Benefits

  • No sensor cleaning
  • Works at Raw Waste Water Inlets
  • No filters needed
  • Minimum maintenance (every 3 to 6 months depending on water quality)
  • Stable and reliable measurement
  • Not affected by fouling, turbidity and suspended solids in a typical application
  • Reagent costs less than £100 per year
  • Does not block
  • Alarms to SCADA and other communications interfaces

Monitoring of ammonia in raw wastewater

Ammonia levels at the intake can change a lot from day to day and from hour to hour. No instrument to date is able to measure ammonia at the raw wastewater inlet (soon after the screens) without an extensive maintenance regime or filtration system. If there was an instrument able to measure ammonia levels soon after the screens operators could:

  • Improve the overall outgoing water quality
  • Save on electricity costs
  • Reduce chemical usage
  • Optimise their process
  • Identify serial offenders
Minimum Maximum
Supply Voltage 90 V AC 240 V AC 50 Hz or 60 Hz
Power Consumption at 20 °C Operating Temp 70 W
Power Consumption at 5 °C Operating Temp 250 W Includes heater
Sample Lift Height 6 m
Working Temp: Ambient -10 ̊ C 50 ̊ C In still air, out of direct sunlight
Working Temp: Water 1 ̊ C 50 ̊ C
Sampling Interval 30 mins 60 mins High concentrations may limit the minimum time period allowed
System Enclosure Glass Reinforced Plastic
NaOH Consumption per Year 30 litres 60 minute sampling
Detection Range 1 ppm
20 ppm
200 ppm
500 ppm
Repeatability -2% +2%
Analogue Output 4 mA 20 mA Scalable to range required, max load 900 Ω
Analogue Output Isolation 400 V
Digital Interfaces Profibus, Modbus
Relay Voltage 50 V Alarm 1 and Alarm 2 Relays with NO and NC contacts
Relay Current 5 A
Weight 75 kg
Dimensions 750 x 750 x 350 mm

View Datasheet

Title Type Format
MS3500 - Wastewater Ammonia Monitor Datasheet PDF
Press Release - Ammonia Monitor Trial Completed Case Study PDF
Ammonia monitor (Raw wastewater Inlet) Case Study PDF
Principle of Operation

The MS3500 utilizes a contactless measurement technique based on Henry’s Law, sensing headspace gases or volatiles in the sampling tank provided, and provides a measurement system with very low maintenance requirements.

Thanks to the clever design and technology the sensor never touches the water. This results in no sensor cleaning , reduced drift, virtually no fouling and very low maintenance.

The MS3500 is accurate to low ppm concentrations and its wide dynamic range allows it to be used in a wide variety of environments. Using minimal reagents and consumables the running costs of the system are very low.

The MS3500 is accurate from 1 to 200 ppm and its wide dynamic range allows it to be used in many applications.

A sample of gas is then taken from the headspace, passed through the sensor and the response analysed to provide a concentration in ppm of the ammonia in the water (Fig. 2).

What does the MS3500 Ammonia Monitor actually measure?
The MS3500 measures the concentration ammoniacal nitrogen in wastewater, as given by the sum of NH3 and NH4
How often does the instrument provide a reading?
The standard instrument gives a measurement every 60 minutes. This time will be cut to 30 minutes or less with the next generation sensors we are testing at the moment (July 2020)
What is the reported value?
The reported value, in ppm, is the sum of NH3 and NH4. What is the principle of operation
How is the MS3500 calibrated?
The instrument is factory calibrated, no user calibration is required, and is validated on-site.
What is the required maintenance? Is it expensive?

The instrument requires a service every 6 months, including a sensor replacement, as part of an inexpensive service pack. This is part of a sensor replacement scheme which can be discussed with Multisensor or your distributor.

Sodium hydroxide might need to be replaced every 3 months, the cost should be less than £100 per year.

What is the warranty?
Every instrument comes with 1 year warranty from the shipment date
What is the main difference between the MS3500 and other ammonia monitors?
The MS3500 is the only ammonia analyser in the market that can reliably work at the intake of a wastewater treatment plant. It can do this thanks to its contactless technology and to its robust sampling system, which is not prone to blockages, even in difficult applications
Why should I measure the ammonia levels at the intake?
By measuring the levels of ammonia at the intake you can optimise the removal, avoid problems in case there is a huge peak and potentially improve the energy costs.
How difficult is the installation of the system?
The installation of the MS3500 is very straightforward: you just need to connect power and position the instrument at the intake. The enclosure can be mounted on a frame and the tubing for sample in and out does directly into the wastewater channel
Why does the MS3500 not block?
The MS3500 acquires its sample through the use of auto-sampler technology combined with e-nose detection techniques. This means that the sample tubes are high diameter, the sample lines a pre purged before a sample is taken and no pump components are in contact with the waste water.

The MS3500 features on Dutch Television

In July 2019 the MS3500 ammonia monitor featured on Dutch Television as part of a documentary on innovative water treatment technologies. Thanks to the support of our Dutch distributor, Technische Alliantie, the MS3500 has now been seen by tens of thousands of people all over the Netherlands.

The video describes how the ammonia monitor is used to measure levels of ammonia in a wastewater plant, using a contactless technology, based on the e-nose sensor and Henry's Law.

"This is a great advantage for the operators who don't need to worry about expensive cleaning routines associated with traditional ISE sensors."

System Introduction

Case Studies

The Ammonia Monitor has been used in numerous applications. We are now working to bring these case studies to you.

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