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Reducing nitrate levels in water with denitrifying bacteria Featured science projectScience project video


This science fair project was conducted to ascertain the effect of introducing denitrifying bacteria to water contaminated with nitrates.


Nitrate-rich water containing denitrifying bacteria will exhibit a faster rate of reduction in nitrate levels.

Scientific Terms

Ammonia, nitrates, nitrite, denitrification, metabolize, enzymes, anaerobic, nitrogen cycle


Nitrate contamination

The use of fertilizers to improve soil fertility and enhance plant growth has resulted in the contamination of nitrogen compounds such as ammonia, nitrate and nitride in our rivers, lakes and ocean. During soil erosion or heavy rain, flowing water will wash nitrates into the nearest lakes and rivers. This causes the pollution and contamination of the water.
The presence of nitrates in rivers and lakes encourages the growth of algae in the water. The growth of algae will reduce the levels of dissolved oxygen in the water and this poses a problem for the survival of the fish and other living organisms in the water.

Denitrifying bacteria helps to metabolize nitrogen compounds using enzymes to release nitrogen gas. This is an anaerobic process and will only take place in an environment where there is very little oxygen. It is a common occurrence in deep soil and stagnant water. This process is part of the nitrogen cycle, releasing nitrogen gas back into the atmosphere.

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Complexity level:
Project cost ($):
Time required:
1 day for preparation, 21 days for observation
Material availability:
Easily found
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