Citric Acid for Water Treatment: Everything You Wanted to Know

What Is Citric Acid?

Citric acid, with the chemical formula C₆H₈O₇, is a weak organic acid that belongs to the family of alpha-hydroxy acids. It is naturally occurring in various fruits, including lemons, oranges, and grapefruits, giving them their distinct sour taste. The compound exists in the form of colorless crystals or a white crystalline powder. Citric acid is highly soluble in water, making it easy to dissolve and mix with other substances.

Citric Acid: Preparation

The preparation of citric acid involves the fermentation process, primarily utilizing Aspergillus niger, a filamentous fungus. The microorganism converts carbohydrates, such as sucrose or molasses, into citric acid through a series of biochemical reactions. The fermentation process involves controlling various parameters, including temperature, pH, and oxygen supply, to maximize citric acid production.

Once the fermentation process is complete, citric acid is extracted from the fungal culture broth. The broth is treated with lime or calcium hydroxide to neutralize its acidity and form calcium citrate, which is insoluble in water. The calcium citrate is then reacted with sulfuric acid to yield citric acid in its pure form, which can be further crystallized and dried.

Application of Citric Acid in Water Treatment

• pH Adjustment

One of the primary applications of citric acid in water treatment is pH adjustment. It is commonly used to lower the pH of alkaline water, making it more suitable for various processes and applications. Citric acid can be added to water to reduce the pH and neutralize alkalinity, ensuring that the water is within the desired pH range.

• Cleaning Agent

Citric acid is also used as a cleaning agent in water treatment. It is effective in removing scale, mineral deposits, and rust from pipes, tanks, and other equipment. Citric acid's acidic properties help break down and dissolve these deposits, keeping the water system clean and free from contaminants.

• Chelating Agent

Citric acid is a powerful chelating agent, meaning it can bind to metal ions and prevent them from forming deposits or causing other issues in the water system. This helps in preventing scale formation, corrosion, and blockages caused by metal ions such as calcium, magnesium, and iron. By chelating these metal ions, citric acid helps maintain the efficiency and longevity of water treatment equipment.

• Disinfection

Citric acid can also be used as a disinfectant in water treatment. It has antimicrobial properties that can help kill or inhibit the growth of certain bacteria, viruses, and fungi. Citric acid can be used in combination with other disinfectants to enhance their effectiveness and provide a broader range of disinfection.

• Anti-scale Agent

Citric acid is used as an anti-scale agent in water treatment to prevent the formation of scale on surfaces and equipment. Scale, typically composed of calcium and magnesium compounds, can build up over time and reduce the efficiency of water treatment systems. Citric acid helps prevent scale formation by sequestering these metal ions and preventing them from precipitating and forming scale.

• Odor Control

Citric acid can be used to control unpleasant odors in water. It can help mask or neutralize the odor-causing compounds present in water, improving its overall quality and smell.

Overall, citric acid is a versatile compound that plays a significant role in water treatment processes, ensuring water quality, preventing equipment damage, and maintaining overall system efficiency.