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Getting a grip on ammonia

Richard Hall

July 15, 2021
 Richard Hall, 
 Continuous Water Analyzers Market Manager,
 Measurement & Analytics

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A natural compound found widely in the environment, ammonia is simply a compound of nitrogen and hydrogen with the formula NH3. Usually found in low concentrations in many natural water sources, ammonia can be harmful if allowed to reach excessive levels.

While much has been done worldwide to reduce ammonia levels in the environment, emissions levels remain a concern, with further reductions still needed to help improve both air and water quality. 


Ensuring a healthy aquatic environment in streams, rivers and lakes relies on close control of ammonia and other substances that could impact on water quality. (Picture credit: Shutterstock.com)

In a concentrated form, it is both a caustic and hazardous substance and is toxic to both fish and other aquatic organisms. It can also overstimulate plant growth or cause algal blooms, leading to a drastic reduction in the oxygen needed to support aquatic life. If not addressed, an over-abundance of ammonia can be catastrophic, killing off aquatic life, and rendering streams, rivers and lakes lifeless.

For this reason, ammonia therefore needs to be closely monitored, with levels higher than around 0.1 mg/L indicating a polluted water source. Ammonia can enter the aquatic environment via direct means such as municipal effluent discharges, industrial processes and agricultural run-off, and indirect means such as nitrogen fixation and the excretion of nitrogenous wastes from animals.

When it comes to potable water, although ammonia in drinking water is not considered to be an immediate risk to human health, it is nevertheless desirable to keep it under control. Excess concentrations can reduce the efficiency of the disinfection processes, form nitrites in distribution systems, cause manganese filters to fail and lead to taste and odour problems. 


A rising problem

Whilst significant inroads have been made in reducing emissions of other environmentally harmful substances, ammonia has been bucking the trend, with emissions levels rising or not reducing as quickly as desired.

In OECD countries, emissions of ammonia decreased in the period between 2003 and 2015. However, this was lower than between 1993 and 2005[1]. Much of this is attributable to agriculture, which has used organic and inorganic fertilisers in growing quantities. 

Although there are a number of sources, the agricultural sector accounts for around 80-90 per cent of total global ammonia emissions[2].

For example, in the EU, agricultural activities resulted in the emission of 3.6 million tonnes of ammonia in 2013. Although this was a decline of almost 30 per cent compared with 1990, agriculture was still responsible for over 93 per cent of total ammonia emissions in the EU-28 in 2013[3].

Much of the rise in ammonia levels can be attributed to fertilisers used in agriculture. (Picture credit: Shutterstock.com).

Keeping levels under control 

To help reduce the risk of environmental damage caused by ammonia, effluent must be treated extensively to minimize levels as far as possible before being discharged to the environment. Ammonia can be removed from water using one of four main methods – aeration, ion-exchange, breakpoint chlorination and biological denitrification.


Monitoring at strategic stages of the treatment process is critical, because it is a colorless and odorless in small amounts, the only way to detect it is through testing and analysis.

When evaluating ammonia testing, a device offering continuous measurement offers several advantages over purely manual methods. Samples are automatically extracted and analyzed at regular intervals at the point of extraction. With manual methods, time lost between extraction of the sample and subsequent testing often affects the value of the result.

Continuous monitoring also offers real-time indication of current process conditions. In contrast, manual testing methods only provide results for the moment in time when the test is made – there is no way of knowing what is currently happening in the process.

Access to real-time information allows immediate action to be taken if any issues occur. 


Keeping tabs on ammonia

One instrument that meets these requirements is the ABB Aztec 600 ISE ammonia analyzer. This device provides reliable and accurate measurement of ammonia concentrations for a wide variety of applications, including source water monitoring and wastewater nutrient removal.

The Aztec 600 uses a robust gas sensing ammonia electrode to provide accurate and reliable continuous measurement of the total ammonia nitrogen (TAN) concentration - the sum of the gas NH3 and the cation NH4+.

Featuring ABB's intuitive menu-driven software and the robust ISE sensing system with automatic calibration, the analyzer is both simple to operate and maintain.

Low maintenance features include low reagent consumption, with up to three months continuous measurement before reagent needs to be replenished. With intuitive software and full colour graphical display, the Aztec 600 also offers data logging and graphical process trending.

It provides a measurement range of 0.050 to 1000 mg/L, but some applications may demand a device capable of a lower range. This is where the Aztec AW632 comes in. It offers reliable and highly accurate measurement of low-level ammonia concentrations, of 0 to 3 mg/L, for a wide variety of applications, from drinking water influent to wastewater effluent.


Get a grip

With ammonia levels in the environment on the rise and growing numbers of countries committed to reducing them, we all need to play a part in keeping this problematic chemical in check.

References:

[1] https://www.oecd-ilibrary.org/sites/92389a36-en/index.html?itemId=/content/component/92389a36-en

[2] https://www.oecd-ilibrary.org/sites/92389a36-en/index.html?itemId=/content/component/92389a36-en

[3] https://ec.europa.eu/eurostat/statistics-explained/index.php?title=Archive:Agriculture_-_ammonia_emission_statistics

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