Water Treatment: Methods and Technological Processes

1. What is Brackish Water?

Brackish water, also known as saline water, is water with a dissolved salt content exceeding the specified limit. Therefore, when consumed, it may taste slightly salty or brackish.

The main reason for the formation of brackish water is the intrusion and dissolution of seawater into the mainland. This process leads to the contamination of groundwater and surface water in that area with a certain amount of salt.

Simply put, brackish water is a mixture of saltwater and freshwater. Typically, the salt concentration in brackish water ranges from 1 - 10 g/l. This type of water cannot meet the standards to become clean water for drinking or household use by the population or in various industrial sectors.

2. Why is Brackish Water Treated?

Brackish water has serious impacts on human life and various industrial and agricultural sectors. Specifically:

2.1 Impact of Brackish Water on Humans

• Brackish water has the ability to draw water out of human cells, leading to dehydration, cell shrinkage, cell aging, and loss of the protective barrier against bacteria. People who drink brackish water are prone to dangerous diseases such as diarrhea, intestinal inflammation, etc.
• Using brackish water extensively can weaken the immune system in the body, creating opportunities for infectious diseases, liver failure, and kidney failure to develop.
• Brackish water is also a cause of skin diseases such as dermatitis, scabies, acne if used regularly for bathing.
• Brackish water is also identified as a factor leading to eye diseases, vaginal infections, etc.

2.2 Impact of Brackish Water on Industrial and Agricultural Sectors

• In agriculture, brackish water causes soil to lose its nutrient content, leading to crop failure, dried-up plants, and nutrient loss. This directly affects the productivity of farmers.
• In industry, brackish water corrodes metal tools and equipment, reducing the efficiency and lifespan of products. Moreover, for industries using steam boilers, brackish water can cause equipment damage or even boiler explosions.

Therefore, brackish water has serious impacts on human life and various sectors such as industry and agriculture. Hence, comprehensive treatment measures are needed to convert brackish water into freshwater before use.

3. Methods of Treating Brackish Water

3.1 Heat Distillation Method

The principle of heat distillation is to heat water until it boils, allowing the water to evaporate and then condense back into pure water.

Heat distillation is a traditional method that has been used for a long time. It can treat all types of brackish water with different levels of efficiency, and it is cost-effective. However, the drawback of this method is that it takes a considerable amount of time and fuel.

3.2 Ion Exchange Method

• The ion exchange method is also very effective in removing salt from brackish water. The mechanism of this operation involves using ion exchange resin beads with water to soften and remove hardness from water.
• The ion exchange method is considered highly effective in treating brackish water. Additionally, the filter materials can be rinsed, regenerated, and reused multiple times. Moreover, the quality of the treated water meets high standards. However, treating brackish water with ion exchange has the disadvantages of high costs and relatively difficult household-level operation.

3.3 Reverse Osmosis Method

This is a method of water filtration through RO membranes. These membranes have extremely small pore sizes, only 0.0001 micron, so they can retain all dissolved salt ions in the water.

Currently, RO reverse osmosis can treat almost all water sources. However, if the salinity of the water is too high, the treatment efficiency may be reduced. Additionally, operation requires electrical energy to create water pressure to push water through the membrane.

4. Brackish Water Treatment Technology Process

• Brackish water from rivers, streams will be sent to a sand settling tank. Before that, this water passes through weirs, which retain large-sized debris in the water before reaching the settling tank.
• In the sand settling tank, the water will settle to remove sand, gravel, and easily settleable substances.
• Next, the brackish water is sent to intermediate tank 1. This facility stabilizes the water flow before sending it to the brackish water to freshwater filtration system behind it.
• The brackish water continues to the coagulation tank to carry out the coagulation and flocculation process. Here, suspended solids will be linked to form large flocs that easily sink to the bottom. To enhance efficiency, chemicals such as PAC (Poly-Aluminum Chloride), Aluminum Phenol, Iron Phenol, and Polymers are often added to promote coagulation and sedimentation.
• The upper part of the coagulation tank will flow to intermediate tank 2. This tank concentrates the water before pumping it to the water softening tank. In the softening tank, the water is softened and then flows to settling tank 2.
• In settling tank 2, any remaining impurities in the water will be precipitated and removed. The water will then flow to intermediate tank 3 and be sent to the water filtration tank.
• The water filtration tank typically uses the following materials: activated carbon, ion exchange resin beads, fine filter core, RO reverse osmosis membrane. The water after filtration will be chlorinated before entering the storage tank for disinfection.
• After the brackish water treatment process, this water has met the standards and can be used for daily activities, cooking, etc.

Above is the information about treating brackish water. We hope that the information provided has helped you understand this issue better and choose the appropriate treatment technology and process. If you have any further questions, please contact the hotline for advice and support from experts.