Applied in water treatment! What are the effects of calcium oxide and calcium hydroxide, and what should be paid attention to?

The application effect of calcium oxide in water treatment

1. Calcium oxide reacts violently with water, producing calcium hydroxide and releasing a large amount of heat. The high temperature and strong alkaline environment generated can effectively kill pathogens such as bacteria, viruses, and parasites in water, and has good disinfection and sterilization effects.

2. It can react with phosphate ions in water to generate calcium phosphate precipitation, thereby removing phosphorus from water and having a good effect on preventing eutrophication of water bodies.

3. It can significantly increase the pH value of water and is suitable for neutralization treatment of acidic wastewater. Moreover, due to its rapid reaction, it can significantly adjust the acidity and alkalinity of the water in a short period of time.

4. Mainly used for pre-treatment of industrial wastewater with strong acidity, acute sterilization and disinfection, and water bodies with high requirements for phosphorus removal. For example, in the pretreatment of acidic wastewater such as electroplating wastewater and printing and dyeing wastewater, calcium oxide can quickly neutralize the acidity while removing some heavy metal ions and phosphorus elements.

Precautions

1. When reacting with water, a large amount of heat is generated, and improper operation may pose a safety hazard. Meanwhile, due to the rapid reaction, if the dosage is not controlled properly during the dosing process, it can easily lead to excessive alkalinity in the local area, which has adverse effects on subsequent treatment processes.

2. Calcium oxide easily absorbs moisture and carbon dioxide from the air and deteriorates, requiring sealed storage and strict requirements during storage and transportation.

Application of Calcium Hydroxide in Water Treatment

1. Calcium hydroxide has relatively good solubility in water and does not produce violent exothermic reactions. It can slowly release hydroxide ions, increase the pH value of the water and be relatively stable, which is beneficial for the stable operation of subsequent treatment processes.

2. Calcium hydroxide can react with many heavy metal ions to form insoluble hydroxide precipitates, effectively removing heavy metals such as lead, mercury, cadmium, etc. from water.

3. Commonly used for advanced treatment of drinking water, urban sewage treatment plants, and industrial wastewater treatment that requires high pH stability. For example, in the purification process of drinking water, hydrated lime can adjust the pH value of the water while removing some heavy metal ions and impurities, ensuring the safety and quality of drinking water. In urban sewage treatment plants, the effluent after biochemical treatment may still contain a certain amount of heavy metal ions and residual acidic substances. Adding calcium hydroxide can further remove heavy metals and adjust the pH value to an appropriate range to meet the discharge standards.

Precautions

1. The solubility of hydrated lime in water is relatively low. When a large amount of wastewater needs to be treated or pH adjustment is required, a larger dosage may need to be added, which increases the difficulty and cost of operation.

2. When calcium hydroxide solution flows in the pipeline, if the concentration is too high or the residence time is too long, it may form sediment on the inner wall of the pipeline, causing pipeline blockage. Regular cleaning and maintenance are required.