How Salt and Organic Waste Affect Ammonia Treatment in Industrial Water

Greg Howard
5th March, 2024

How Salt and Organic Waste Affect Ammonia Treatment in Industrial Water

Image Source: Natural Science News, 2024

Key Findings

  • Study from Chongqing University found that microorganisms can effectively remove ammonia from very salty industrial wastewater
  • Ammonia-oxidizing archaea (AOA) showed better survival and activity in high-salt conditions than ammonia-oxidizing bacteria (AOB)
  • When actual industrial wastewater was used, AOA present in the water boosted the ammonia removal process
Understanding the process of removing harmful nitrogen compounds from wastewater is crucial for environmental protection and public health. Nitrogen, primarily in the form of ammonia, is a common pollutant in wastewater that can lead to eutrophication, harming aquatic life and water quality. Microorganisms that convert ammonia into less harmful substances play a vital role in this process, known as nitrification. Among these microorganisms, ammonia-oxidizing archaea (AOA) and bacteria (AOB) have been the focus of much research. Recent findings from the Chongqing University of Science and Technology[1] have shed light on the behavior of AOA in extremely salty, or hypersaline, conditions, which are common in certain industrial wastewaters. This study is particularly relevant as it addresses the gap in understanding AOA activity in such challenging environments. The study involved two sequencing batch biofilm reactors (SBBRs), which are systems used to treat wastewater by cycling it through periods of aeration and rest in the presence of biofilms—thin layers of microorganisms that grow on surfaces. The researchers tested the effects of salinity, organic matter, and actual pickled mustard tuber wastewater (PMTW) on the activity of AOA and AOB. Despite the high salt concentration of 70 grams of NaCl per liter, which is known to inhibit microbial activity, both AOA and AOB managed to maintain high ammonia removal efficiency. However, when the levels of salt and organic matter increased, the specific rates at which these microorganisms converted ammonia to other compounds decreased significantly. This was demonstrated by both the direct measurement of ammonia oxidation rates and the quantification of the amoA gene, which is essential for ammonia oxidation and serves as a marker for the presence of these microorganisms. Interestingly, AOA showed a higher tolerance to high salinity and organic content compared to AOB. As the salinity increased, AOA became more dominant in the reactors, suggesting a potential shift in the microbial community from AOB to AOA dominance in such conditions. This finding is particularly important for the treatment of industrial wastewaters, which often have high salinity levels. The study also found that when the reactors were fed with PMTW, the AOA already present in the wastewater contributed to an increase in both the abundance and activity of the AOA in the reactor, further improving the efficiency of ammonia removal. These findings align with previous studies that have highlighted the diverse environments in which complete ammonia-oxidizing (comammox) Nitrospira, a type of AOB, can be found[2], as well as the presence of Nitrospira and other nitrogen-cycling microorganisms in sand filters of drinking water treatment plants[3]. Moreover, the study complements research showing that comammox bacteria are dominant in municipal wastewater treatment plants but less so in industrial settings[4], suggesting that AOA may play a more significant role in certain industrial processes. The results from Chongqing University of Science and Technology contribute to our understanding of nitrification in hypersaline environments and highlight the potential of AOA as a robust option for treating high-salinity industrial wastewater. This knowledge can inform the design and operation of treatment plants to ensure efficient removal of ammonia from wastewater, protecting water resources and the environment from the adverse effects of nitrogen pollution.

EnvironmentBiotechMarine Biology


Main Study

1) Impact of salinity and organic matter on the ammonia-oxidizing archaea and bacteria in treating hypersaline industrial wastewater: amoA gene abundance and ammonia removal contributions.

Published 4th March, 2024

Related Studies

2) Salinity changes the nitrification activity and community composition of comammox Nitrospira in intertidal sediments of Yangtze River estuary.

3) Nitrogen-metabolising microorganism analysis in rapid sand filters from drinking water treatment plant.

4) Comammox bacteria predominate among ammonia-oxidizing microorganisms in municipal but not in refinery wastewater treatment plants.

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