What is the sedimentation of drinking water

The water that reaches our homes comes from rivers, streams, lakes, reservoirs and groundwater deposits. This water naturally contains microorganisms (cyanobacteria, diatoms, dinoflagellated …), organic matter and inorganic particles, such as metals. The water we drink does not have the same characteristics as the water we find in nature. For Avoid the risks that non -potable water supposes for healththis must suffer a Dringing process which consists in the elimination of microorganisms and the particulate material in suspension to be suitable for human consumption. The Water purification It occurs in centers called drinking water treatment stations or ETAP, or in water water or EPA stations.

In the water purification stations, two main processes occur that consist of a place in the elimination of the particles in the water and, on the other hand, in the inactivation of the microorganisms. The water reaches the treatment stations by a series of pipes, aqueducts or built channels that connect the water outlet areas with the stations. The Water purification treatments that occur in these plants are:

• Coagulation: The water enters the “fast mixing” tanks. A series of coagulant and chlorine polymers are added to create compounds that are then sediment and eliminated. Chlorine is added to disinfect water from pathogenic microorganisms. In these tanks the water moves at great speed to favor a greater union of the chemicals added with the water particles.
• Flocculation: Then the water passes to the flocculative tanks. Here, the water moves more slowly to encourage the formation of floccles or lumps of the suspended solids in the water.
• Sedimentation: Next, the water moves to other tanks so that the floccles sedimente. For this it is necessary for water to move very slowly.
• Filtration: The water moves towards filters for the elimination of small suspended particles that have not been eliminated before, such as remains of microorganisms, algae, smaller flocs, etc. Normally the filters are of sands, gravels and activated carbon.
• Storage: Finally, drinking water is stored to other tanks where chlorine and fluorides are also usually added to disinfect water from possible microorganisms that have not been previously eliminated and also so that they do not proliferate as long as the water is stored in these tanks. From here the water is distributed to the populations by means of a network of pipes.

You may also be interested in completing the information with this other ecology article about the different types of wastewater treatment.

Sedimentation is the process by which The solids that are in suspension in the water fall to the bottom of the container where the water is contained. Sedimentation is a natural process which occurs due to the effect of gravity. Although it happens in rivers and lakes, people have used this phenomenon to achieve a purest and safer water.

Sedimentation is based on Stokes’s law, according to which the largest or heaviest particles that water will have a greater sedimentation capacity. It also influences the viscosity of the liquid, the lower viscosity greater capacity and sedimentation speed.

Suspension particles can be classified according to their diameter and suspension state:

• Suspension particles of up to 10^-4 cm.
• Colloids with sizes particles between 10^-4 and 10^-6 cm.
• Solutions with particles of less than 10^-6 cm.

Based on this classification, there is a parallel way to classify methods or Water sedimentation types According to these types of particles:

• 1st case: simple sedimentation. The particles up to 10^-4 cm are capable of sedimenting only by physical processes, such as gravity.
• 2nd Case: Colloids must coagulate to form sedimentable floccles. It is necessary to add chemicals.
• 3rd Case: Soluble substances must become insoluble to form sedimentable floccles. As in the previous case, the addition of chemicals is necessary.

In order for the sedimentation of the particles to occur, it is necessary that the speed of the water flow is less of the sedimentation speed of the suspended solids they contain. This concept of superficial load is essential when building sedimentation tanks.

Some Examples of speeds and times sedimentation They are, for a distance of 0.3 m, 38 seconds for grains of sand with a speed of 88 millimeters per second (mm/s), 35 hours for bacteria conglomerates with a speed of 0.00154 mm/Sy in the case of colloids the time could amount to 63 years and a speed of 0.000000154 mm/s. Naturally, the sedimentation speed also depends on other factors such as water temperature and diameter and the specific weight of the particles.

The sedimentation tanks They can be circular or rectangular and have four different parts.

• Entrance zone: It is the area through which the water enters the sedimentation tank. It is necessary to control the speed to avoid turbulence. Water usually enters with a speed not exceeding 5 cm/s.
• Sedimentation zone: It requires that there be a uniform and slow flow to facilitate the deposition of the particles at the bottom, where the sludge area is located.
• Sludge Zone: The sludge are the result of the deposition of the solid particles contained in the water. In the base there is a spring through which sludge is extracted. It is also necessary to remove them to avoid the obstruction of said springboard, but it must be done at a very low speed to avoid its resolution.
• Output zone: It is the area through which water leaves this tank. In addition, it has structures that retain floating water materials.

If you want to read more articles similar to What is the sedimentation of drinking waterwe recommend that you enter our category of other ecology.