Currently, many water plants still apply the following basic steps to treat groundwater and surface water into domestic water. However, the actual quality of water after treatment is still contaminated with heavy metals or arsenic. The trend of groundwater and surface water sources is becoming increasingly polluted, so the process of supply water treatment will require many stages as well as better treatment efficiency than the existing technology.

  1. Reservoir and preliminary settling: Creating favorable conditions for the self-cleaning process: settling suspended sediments, reducing the amount of germs due to environmental conditions, performing oxidation reactions due to the effect of dissolved oxygen in water and on duty regulating the flow between the flow from the source to the consumption flow supplied by the raw water pumping station to a water treatment plant.
  2. Trash rack: Eliminate suspended objects in the water stream to protect equipment and improve the cleaning efficiency of treatment facilities. Floating objects and suspended objects in water can be as small as a toothpick; when passing through the pump into the treatment facilities, they can be scattered or rotten to increase the color, the content of water residues.
  3. Sand settling tanks: In surface water sources with large turbidity (> 250mg / L) behind the screens, inorganic suspended particles, small in size, larger density than water, hard, capable of fast settling are retained in sand settling tanks.
  4. Treating water at source with chemicals: To limit the growth of algae and water microorganisms, eliminate color, smell, taste caused by corpses vs substances. The most commonly used chemical is CuSO4, dosage of 0.12 – 0.13 mg / l. The dosage and interval between treatments depends on the composition of raw water as well as the concentration of organisms and algae, temperature, alkalinity and CO2 content.
  5. Clearance: Dissolve oxygen from the air into water to oxidize valence iron II, valence manganese II to iron III, manganese IV to form Fe (OH) 3 hydroxide compounds that have the ability to precipitate and settle.
  6. Preliminary chlorine: Add chlorine to water before settling tank and filter. Extend contact time for sterilization when water sources are heavily contaminated. Oxidation of dissolved iron in the form of organic compounds, oxidizing dissolved manganese to form the corresponding precipitate compound. Oxidizing organic substances to remove color. Preventing the growth of algae in the reaction tanks and settling tanks, destroying the cells of microorganisms producing mucus on the filter surface, increasing the filter cycle time.
  7. Stir chemicals: Facilitate rapid and even dispersion of chemicals into the entire volume of water to be treated because the reaction of hydrolysis of the flocculation is very fast (usually less than 1 / 10s), if not mixed well and prolonged drag will not occur. creating sufficient, firm and even flocculants in the volume of water, the deposition effect will be poor and alum-consuming. Other chemicals require mixing while mixing time requires less strict than alum.
  8. Flocculation and flocculation reaction: Create kernels capable of binding waterborne contaminants in suspended form into a flocculant capable of settling in settling tanks and adhesion on the grain surface of the filter media layer at a fast and economical rate. The most delicate. When curing alum with treated water immediately, chemical and physical reactions occur to form a positive colloidal system that disperses evenly in the water, when neutralized, this positive colloidal system is the most capable of adhesion to Negative glue disperses in water to form residues. Therefore, the process of creating a flocculation is called the process of flocculation, the process of coagulation, and the flocculation process is called a flocculation reaction. Often use alum and iron alum
  9. Clarify: Deposition is the process of reducing the concentration of suspended sediments in the source water by means of: Gravity deposition in sedimentation tanks, when radical particles have a density greater than water in appropriate hydraulic regime will settle down; By centrifugal force acting on the residue particles, in centrifugal sedimentation tanks and hydraulic ciclon; By floating thrust due to air bubbles sticking to sediment particles in the flotation tanks. Along with sedimentation, the settling process reduces 90-95% of the bacteria in the water because the bacteria are always adsorbed and stick to the cottonseed particles during sedimentation.
  10. Filter: Filtering is a process that not only retains suspended particles in water that are larger than the pores created between the filter particles but also retains iron, organic colloidal particles that cause turbidity and color. the size is much smaller than the size of the pore fish but it has the ability to stick and absorb on the surface of the filter material layer.
  11. Absorbing odors, coloring: The activated carbon particles have a very large active surface, capable of absorbing gas molecules and liquids dissolved in water, making the water flavor and color on the surface of this coal particle out. country. The water is deodorized and colored.
  12. Fluoridation: Because after the water treatment process, the amount of fluorine in the water is lower than the standard, so it is necessary to add fluorine to the water.
  13. Antiseptic: To ensure bacteriological safety, water before being supplied to consumers must be disinfected. Disinfection measures include: Boiling water, Using ultraviolet rays, Using substances with high sterilizing effect such as oozon, chlorine, …
  14. Water stability: The process of water stabilization is the process of reducing the erosion of water and implanting on the inner wall of the protective film pipe to insulate water from direct contact with the pipe-making material.