A NITRATE AND NITRITE ANALYSER FOR THE TOUGHEST OF AUTOMATED, REAL-TIME MONITORING JOBS


Aquamonitrix® is a revolutionary new real-time analyser for the simultaneous detection of nitrate and nitrite in potable water, wastewater, environmental monitoring and aquaculture applications.


The analyser features a blockage-resistant sample-intake line, allowing for robust operation even in wastewater. Furthermore, nitrate and nitrite are measured independently from the same sample, with two discrete readings.


Other benefits include laboratory-quality accuracy; instant data transmission; stable calibration; intervention- and maintenance-free operation; portability; ease of set up and servicing; and low opex costs.


Monitoring in challenging wastewater applications


Nitrate can be a problem in effluent discharged by municipal wastewater treatment plants, intensive poultry and pig farms, aquaculture and several key manufacturing sectors.


Many conventional real-time, autonomous nitrate/nitrite analysers suffer from accuracy drift and frequent recalibration needs and/or biofouling and blockages in wastewater. This adds up to a frustrating user experience and sees some wastewater plant operators continue to rely on traditional manual grab sampling and laboratory analysis – with all the associated costs, requirements for skilled personnel and inherent delays in receiving results.


In contrast, Aquamonitrix® is robust enough to withstand challenging wastewater matrices, while still delivering accurate, real-time results with low intervention and maintenance requirements.


•The analyser combines rapid ion chromatography and UV LED detection. As illustrated in Figure 1 below, the in-built sample intake system is based on a sample loop through which sample is drawn, filling an internal reservoir. Just a few microlitres are drawn from this reservoir for analysis. The sample passes through an anion exchange separation column and into the custom UV LED-based detector, where nitrite and nitrate are selectively detected. All analyte concentrations and system control data are automatically transmitted in real-time to the user’s choice of proprietary IoT platform, telemetry system and/or SCADA control infrastructure.


• Because of the small (microlitre level) volume of sample required, the simple in-built sampling system is sufficient for most wastewater applications. Even in activated sludge, a simple filter system, costing just a few hundred pounds, is all that’s needed. This compares with conventional UV-based analysers requiring investments of circa £15k for add-on wastewater sampling systems.


Figure 2: The proprietary Datamonitrix platform, illustrating selective detection of nitrite and nitrate Offering intervention-free high-frequency environmental monitoring


Nitrate is increasingly coming onto the agenda as an urgent environmental issue. The whole of Wales has been designated a ‘Nitrate Vulnerable Zone’, and, in the areas surrounding the Solent in England, planning permission for new house building was temporarily halted last year, as deals were thrashed out over nitrate trading and mitigation schemes.


The common requirement for catchment and groundwater monitoring, environmental investigation and nitrate trading schemes is a robust, affordable and practical means for carrying out accurate, high-frequency/high-resolution nitrate monitoring.


Aquamonitrix®


• Within one hour of being unpacked from its box, the Aquamonitrix® sampling and transmitting accurate readings in real-time via IoT to the users’ PCs.


has recently been trialled in a series of three-month surface water monitoring applications. analyser was installed on-site,


• (The sampling line can be deployed directly in a river, reservoir, borehole or lake; eliminating the need for the types of sampling troughs needed for conventional UV detection.)


• As illustrated in Figure 3 below, the readings were in close agreement with the results from grab samples analysed for nitrate in an accredited laboratory


Figure 1: The unique sampling system prevents blockages in wastewater applications


• Over the 13-weeks deployments, the only site visits required were to refill the reagent cartridge and empty the stored waste sample. This simple procedure took less than five minutes and, with hourly sampling, needed to be performed approximately once every 27 days. However, this period could be extended by simply using larger reagent and waste cartridges.


Providing accurate real-time measurements of nitrite independent of nitrate


While automated, real-time analysers are available for nitrate and for total nitrogen or the sum of nitrate plus nitrite, Aquamonitrix®


stands out in the marketplace in providing accurate, real-time


measurements of nitrate and nitrite – simultaneously from the same sample, but with each ion concentration measured discretely/distinctly from one another, as shown in Figure 2 across the page.


Nitrite is an important intermediate across many processes in the water and wastewater industry – and the ability to measure it separate from and/or as a ratio of nitrate is vital in understanding, controlling and optimising these processes.


• One example is biological nitrogen removal (BNR) in wastewater treatment. Short-cut BNR processes that reduce aeration energy requirements aim to either partially or completely avoid nitrate formation and instead convert nitrite directly to nitrogen gas. Here, being able to monitor nitrate and nitrite accurately in real-time can be expected to significantly improve process understanding and dynamics.


In short, the analyser proved itself to truly be a plug, play and forget system while delivering laboratory-quality results in real-time.


• Drinking water producers experiencing intermittent nitrate exceedances can also benefit from real-time readings of nitrate and nitrite as independent entities (rather than as a sum total). Aquamonitrix®


configurable alarms that can alert operators in real-time to nitrate and/or nitrite exceedances.


• Equally, real-time measurement of nitrite separate from nitrate is crucial in identifying, controlling and avoiding nitrification problems in potable water treated with chloramine disinfection on the journey through the distribution network to customers’ taps.


• In yet another sector, biological filters convert built-up ammonia in recirculating aquaculture systems to nitrite and then nitrate, and being able to monitor, in real-time, the build-up of the nitrite intermediate is crucial, given its acute toxicity to fish.


can be deployed on intake and outlet lines in drinking water treatment plants, with


For further information, contact John McGrath, Sales Director Email info@aquamonitrix.com, www.aquamonitrix.com


Figure 3: Comparison of nitrate results from Aquamonitrix®


and nitrate concentrations determined for grab samples using accredited laboratory instrumentation shown in red - January to April 2021.


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