Nitrates are naturally present in the soil, but their content increases due to agricultural fertilizers and industrial wastewater. As a result, they directly pollute water sources through groundwater infiltration, making them one of the common contaminants that need to be taken seriously in drinking water. This article will discuss with you various methods for removing nitrates, how to detect and prevent nitrates in water, and other common problems.
What is Nitrate?
Nitrate is an inorganic compound, a salt composed of nitrogen and oxygen. It is widely present in nature and human activities. It is an important part of the nitrogen cycle and one of the most important nutrients for plant growth. It can be formed naturally through biological processes or synthesized through chemical processes. It is commonly found in soil and water. Nitrates usually come from agricultural by-products, animal manure, and plant decomposition. After nitrates enter groundwater and surface water, they may enter the human body through drinking water, crop irrigation, etc.
What are the sources of excess nitrates in water?
The ways nitrate enters water mainly include domestic sewage, industrial wastewater, agricultural pollution, and automobile exhaust emission.
Agriculture is one of the main sources of nitrate pollution. Farmers usually use nitrogen fertilizers to promote crop growth, but some of the nitrogen fertilizer in the soil is converted to nitrates. At this time, rain, floods, and other rainfall may cause nitrate to enter the groundwater. Industrial wastewater can contain high concentrations of nitrates and, if not properly treated, can be discharged directly into rivers, lakes, or oceans.
How to determine the nitrate content in water?
Nitrates are usually widely present in gaseous water, surface water, groundwater, plants, and animals. So, how to determine the nitrate content in water? Here are three simple methods for you:
Test strips and kits
This method can quickly determine the nitrate content in water and is very inexpensive, making it ideal for home and field testing. You simply mix the water sample with the nitrate test strips and compare the color presented with the standard color to estimate the nitrate concentration in the water. Although this method is simple and convenient, its accuracy is relatively low. Therefore, you can use this method for preliminary screening.
Photometric method
This method is to determine the nitrate concentration by measuring the absorbance of the colored compound produced by nitrate and certain chemical reagents. This method is more accurate than the test paper method, and its sensitivity is also very high. Therefore, this method is very suitable for laboratory analysis.
Ion chromatography
Ion chromatography is a high-precision analytical technique that separates ions in a water sample using a chromatographic column, and then you use a conductivity detector to determine the nitrate concentration. Of course, you can also choose other appropriate detectors for determination.
Ion chromatography has high sensitivity and selectivity. It can simultaneously determine multiple anions, so it is very suitable for the analysis of complex water samples. However, ion chromatography requires more specialized instruments and technicians, and the cost is also very high. It is usually used for research and demanding analysis.
In short, you can choose different methods to determine the nitrate content in water according to your needs. Each method has its advantages and disadvantages, and you need to weigh the accuracy, cost, and operational complexity. Of course, if you have a simpler and more effective method, you can use it as long as it can effectively measure the nitrate content in water.
Are nitrates in water harmful?
Yes, if the nitrate content in water is too high, it may have a great impact on human health and the environment.
Impact on human health
According to a report released by the Minnesota Department of Health, high nitrate levels reduce the ability of red blood cells to transport oxygen throughout the body. If young children are deprived of oxygen, they may suffer from a disease called methemoglobinemia. This is the most serious impact.
In general, drinking water with high nitrate content for a long time may have a direct impact on human health and may even be life-threatening. Therefore, you need to filter the water through a reverse osmosis water purifier before drinking it.
Impact on the environment
High nitrate content can lead to eutrophication of water bodies and promote excessive growth of algae and aquatic plants. If these plants decompose in large quantities, they may consume dissolved oxygen in the water, endangering the lives of aquatic organisms and seriously disrupting the ecological balance. At the same time, nitrates are easily soluble in water and are not easily adsorbed by soil particles, so they seep into groundwater and directly pollute drinking water sources.
How much nitrate is safe in drinking water?
According to the U.S. Environmental Protection Agency (EPA), the maximum allowable concentration of nitrate nitrogen (NO3-N) in drinking water is 10 ppm, so water with nitrate levels below 10 ppm is safe to drink. Nitrate is an environmental pollutant, which means that the pollutant content is subject to regulations. The U.S. Environmental Protection Agency also sets maximum levels for these pollutants.
How to remove nitrates from drinking water?
Removing nitrates from water is a very important task because drinking water with high levels of nitrates can directly affect human health. Therefore, you must remove nitrates from water by appropriate methods, and the following are four common methods to help you.
Reverse Osmosis (RO) Filtration
Reverse osmosis is an advanced filtration technology that removes all contaminants, including nitrates, from water through a semipermeable membrane. When water molecules pass through the membrane, impurities such as nitrates are blocked on the other side of the membrane, allowing only clean water molecules to pass through. Therefore, reverse osmosis can filter nitrates and other dissolved impurities in water through a semipermeable membrane.
There are many types of reverse osmosis water filtration systems on the market. It is strongly recommended that you use the ITEHIL portable reverse osmosis water filtration system, which uses PP cotton + activated carbon and RO membrane for multiple filtrations. The filtration effect is as high as 99.99%, which can filter almost all contaminants in the water, including nitrates, heavy metals, bacteria, viruses, etc. The portable design is easy to carry, allowing you to get clean and healthy drinking water at any time.
Related: What Is a RO System and How Does It Work?
Ion exchange
Ion exchange is a highly effective way to remove nitrates from water. Ion exchange resins are water-insoluble polymers with reactive groups on their surface. If you are using ion exchange resins to remove nitrates, you will need to use a strongly basic anion exchange resin. This resin has positively charged groups on its surface that can exchange with the negatively charged nitrate ions in the water.
Distillation
Distillation is a physical separation method that uses heat to evaporate water and then condenses the steam to remove impurities from the water. Generally speaking, distillation can almost completely remove nitrates from water. The water obtained by distillation is pure water without any impurities and contaminants. However, this method is generally suitable for laboratories and is very expensive.
Related: What is distilled water? Is it safe to drink?
Electrodialysis
Electrodialysis uses an electric field to separate ions in water. Cations and anions move through a selective membrane under the action of the electric field, thereby removing nitrates. However, it requires professional equipment and technology.
Regardless of the above methods, they can effectively remove nitrates from water. The specific choice depends on your needs and conditions. If it is for home or outdoor drinking water treatment, reverse osmosis and ion exchange are recommended.
Does boiling water remove nitrates?
It can't be removed. Nitrate is an inorganic salt dissolved in water, and it does not break down at boiling temperatures. If you boil water, some of it evaporates, leaving behind dissolved substances, including nitrates.
Therefore, boiling water can not remove nitrate, but will increase the nitrate content of the water.
How to prevent nitrate pollution in water
The following 3 methods can prevent nitrate pollution of water. Only by reducing the use of nitrates in agricultural and industrial activities and adopting appropriate water treatment methods can the problem of nitrate pollution of water quality be further solved.
Reduce fertilizer use
In agricultural production, the use of chemical fertilizers, especially nitrogen fertilizers, should be reduced to reduce nitrate emissions. The use of organic fertilizers or improved fertilizers, as well as appropriate fertilization methods, can reduce the entry of nitrates into water bodies through runoff and infiltration.
Improve industrial wastewater treatment
Wastewater treatment should be strengthened during industrial production to ensure that discharge meets standards and reduces the direct discharge of wastewater containing nitrates into the environment.
Use appropriate water treatment methods
For water bodies that have been contaminated by nitrates, reverse osmosis, electrodialysis, and ion exchange can be used to remove nitrates from the water.
Frequently Asked Questions
Can distilled water remove nitrates?
Distilled water can effectively remove nitrates from water through its physical properties.
Which plants can remove nitrates from water?
Plants that can remove nitrates from water include water hyacinth, duckweed, cattail, reed, water pepper, watercress, water lily, moss ball, etc.
Is tap water high in nitrates?
It depends on the environment of your city. Of course, you can also test the nitrate content in tap water by test paper method, photometry, ion chromatography, and other methods. At the same time, you can also consult the water quality report of the local water department.
What is the fastest way to reduce nitrates?
Ways to reduce nitrates: choose organic foods, store and cook properly, choose vegetables low in nitrates, drink clean water, avoid processed foods, consume more antioxidants, monitor food labels, etc.
Can water softener remove nitrates?
A water softener removes nitrates. It removes hardness from water, including calcium and magnesium ions, through a process called ion exchange, and can also remove other contaminants, such as nitrates.
