COAGULATION AND FLOCCULATION

Coagulation and flocculation processes are used in drinking water treatment and wastewater treatment. The purpose of these processes is to remove colloids from water by precipitation. The diameter of colloids that can be precipitated by the coagulation-flocculation process varies between 1 micron and 1 millimicron. Most of the suspended agent in water is colloidal. This is the cause of turbidity and color. Colloidal substances carry a negative charge. Therefore, they are coagulated by using the trivalent metal salts such as iron and aluminum. This process takes place by polar attraction.

Chemical coagulation of waters is done for various purposes as follows:

• Elimination of organic and inorganic turbidity
• Decoloration
• Bacteria and pathogen elimination
• Elimination of algae and organisms
• Elimination of odor and flavoring agents
• Phosphate elimination
• Elimination of Biological Oxygen Demand and Chemical Oxygen Demand parameters
• Elimination of suspended solids
• Elimination of metals

CLASSIFICATION OF PARTICLES IN WATER

Substances in water are divided into 3 according to their size:

• Suspended agents
• Colloidal agents
• Dissolved agents

Particles in size varying between 1 micron and 1 millimicron are called “colloidal.” For example, a particle having a diameter of 1 micron usually precipitates at a rate of 1 mm/hour, and 1 year is necessary for a particle having a diameter of 0.01 micron to precipitate by 1 mm. Colloids are larger than atoms and small molecules and cannot be retained in the regular filters. There are two types of colloids according to their diffusion in water:

• Hydrophilic colloids
• Hydrophobic colloids

COAGULATION PROCESS

In a wastewater treatment, chemicals added to water to facilitate the precipitation of very small particles suspended with colloidal agents are called “coagulants.” The coagulation process is a process of adding the coagulants to the waste water and then of mixing them into the waste water quickly and making the colloidal agents and suspended solids in the waste water ready to form a flock. Suspended agents and colloids cannot be separated from the wastewater without a very long holding time. This time is reduced highly by adding coagulants. Suspended agents can be removed by a biological treatment, if they are soluble organics. However, if the amount of the insoluble negative agents is high, it is more cost-effective and suitable to apply a chemical coagulation process.

Purposes of the coagulation process:

• To reduce the zeta potential of the colloid; and
• To neutralize the negative charge of the colloid.

In practice, coagulation is a process of mixing the coagulant added to the wastewater quickly in the wastewater.

WASTEWATER TREATMENT SERVICES

Contact Liberta Kimya for your wastewater requirements. We can provide expert advice and support on maintenance, management and treatment of the commercial and industrial boilers and steam generation systems to help you to optimize the costs and operational efficiencies, reduce the downtime, save water and energy, maintain the steam quality and increase plant reliability. We apply the following processes by taking samples from your wastewater in your plants:

• Sample Jar tests (completed within 5 working days)
• Laboratory Reporting (completed no later within 2 working days after the Jar test results)
• Site Jar Testing (the Jar Test work that we will do together again in the facility with our product/products determined in the survey)
• Site Reporting (completed no later within 2 working days after the on-site Jar test results)
• A Quotation (based on annual consumption amounts and contract conditions)
• Site tests (the site tests with chemicals with their results obtained)